Metal Complexes Containing Redox-Active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review

Round 1

Reviewer 1 Report

Shul’pin presented a review manuscript on the metal complexes containing redox-active ligands in oxidation of hydrocarbons and alcohols. The manuscript is generally well-prepared and requires only minor revision.

 

Points to revise:

Line 88: “such as, for example” are redundant.

Line 91: intransitive metal complexes?

Some errors in Figure 3

Line 190: “The complexes include two ammonia molecules. X-Ray diffraction analysis showed that one of the ammonia molecules acts as a ligand, and the other forms an ammonium cation.” I think the first sentence is incorrect. There are one ammonia ligand and one ammonium cation!

Line 285: The charge is not balanced in the chemical equation.

Line 284 to 298: check if the charge is balanced in the chemical equations.

A conclusion or section of future outlook should be added.

  

Author Response

Point-by-point responses to Reviewer 1

 

We thank Reviewer 1 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 1 wrote:

Comments and Suggestions for Authors

Shul’pin presented a review manuscript on the metal complexes containing redox-active ligands in oxidation of hydrocarbons and alcohols. The manuscript is generally well-prepared and requires only minor revision.

 

Points to revise:

Line 88: “such as, for example” are redundant.

Authors response: We removed “for example”

Reviewer 1 wrote:

Line 91: intransitive metal complexes?

Authors response: Should be: complexes of non-transition metals

Reviewer 1 wrote:

Some errors in Figure 3

Authors response: we corrected

Reviewer 1 wrote:

Line 190: “The complexes include two ammonia molecules. X-Ray diffraction analysis showed that one of the ammonia molecules acts as a ligand, and the other forms an ammonium cation.” I think the first sentence is incorrect. There are one ammonia ligand and one ammonium cation!

Authors response: we corrected and wrote:

The complexes include two ammonia molecules. X-Ray diffraction analysis showed that there are one ammonia ligand and one ammonium cation.[37a,b] one of the ammonia molecules acts as a ligand, and the other forms an ammonium cation.

Reviewer 1 wrote:

Line 285: The charge is not balanced in the chemical equation.

Authors response:We corrected:

Equilibrium transformations

Fe³⁺ ↔ FeOH²⁺ + H⁺ K_I

II  Fe³⁺ + H₂O₂ ↔ FeHO₂²⁺ + H⁺     K_II

III. HȮ₂ ↔ H⁺ + Ȯ₂⁻                K_III

Initiation reactions

i1.  FeHO₂²⁺ →Fe²⁺ + HȮ₂                     k_i1

i2.  FeHO₂²⁺ + FeOH²⁺ → 2 Fe²⁺ + H₂O + O₂      k_i2

i3.  FeHO₂²⁺ + H₂O₂ → Fe²⁺ + H₂O + O₂ + ȮH     k_i3

Chain extension reactions

Fe²⁺ + H₂O₂ → Fe³⁺ + OH⁻ + ȮH k₁ ȮH + H₂O₂ → H₂O + HȮ₂ k₂ 2 Fe³⁺ + Ȯ₂⁻ → Fe²⁺  + O₂           k₃

Chain termination reactions

Fe²⁺ + HȮ₂ → Fe³⁺ + HO₂⁻ k₄ Fe²⁺ + ȮH → Fe³⁺ + OH⁻ k₅ HȮ₂ + HȮ₂ → H₂O₂ + O₂ k₆

6’  HȮ₂ + Ȯ₂⁻ →  HO₂⁻ + O₂      k_6’

Reviewer 1 wrote:

Line 284 to 298: check if the charge is balanced in the chemical equations.

Authors response:We corrected:

Equilibrium transformations

Fe³⁺ ↔ FeOH²⁺ + H⁺ K_I

II  Fe³⁺ + H₂O₂ ↔ FeHO₂²⁺ + H⁺     K_II

III. HȮ₂ ↔ H⁺ + Ȯ₂⁻                K_III

Initiation reactions

i1.  FeHO₂²⁺ →Fe²⁺ + HȮ₂                     k_i1

i2.  FeHO₂²⁺ + FeOH²⁺ → 2 Fe²⁺ + H₂O + O₂      k_i2

i3.  FeHO₂²⁺ + H₂O₂ → Fe²⁺ + H₂O + O₂ + ȮH     k_i3

Chain extension reactions

Fe²⁺ + H₂O₂ → Fe³⁺ + OH⁻ + ȮH k₁ ȮH + H₂O₂ → H₂O + HȮ₂ k₂ 2 Fe³⁺ + Ȯ₂⁻ → Fe²⁺  + O₂           k₃

Chain termination reactions

Fe²⁺ + HȮ₂ → Fe³⁺ + HO₂⁻ k₄ Fe²⁺ + ȮH → Fe³⁺ + OH⁻ k₅ HȮ₂ + HȮ₂ → H₂O₂ + O₂ k₆

6’  HȮ₂ + Ȯ₂⁻ →  HO₂⁻ + O₂      k_6’

Reviewer 1 wrote:

A conclusion or section of future outlook should be added.

Authors response:We added conclusions.

Point-by-point responses to Reviewer 1

 

We thank Reviewer 1 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 1 wrote:

Comments and Suggestions for Authors

Shul’pin presented a review manuscript on the metal complexes containing redox-active ligands in oxidation of hydrocarbons and alcohols. The manuscript is generally well-prepared and requires only minor revision.

 

Points to revise:

Line 88: “such as, for example” are redundant.

Authors response: We removed “for example”

Reviewer 1 wrote:

Line 91: intransitive metal complexes?

Authors response: Should be: complexes of non-transition metals

Reviewer 1 wrote:

Some errors in Figure 3

Authors response: we corrected

Reviewer 1 wrote:

Line 190: “The complexes include two ammonia molecules. X-Ray diffraction analysis showed that one of the ammonia molecules acts as a ligand, and the other forms an ammonium cation.” I think the first sentence is incorrect. There are one ammonia ligand and one ammonium cation!

Authors response: we corrected and wrote:

The complexes include two ammonia molecules. X-Ray diffraction analysis showed that there are one ammonia ligand and one ammonium cation.[37a,b] one of the ammonia molecules acts as a ligand, and the other forms an ammonium cation.

Reviewer 1 wrote:

Line 285: The charge is not balanced in the chemical equation.

Authors response:We corrected:

Equilibrium transformations

Fe³⁺ ↔ FeOH²⁺ + H⁺ K_I

II  Fe³⁺ + H₂O₂ ↔ FeHO₂²⁺ + H⁺     K_II

III. HȮ₂ ↔ H⁺ + Ȯ₂⁻                K_III

Initiation reactions

i1.  FeHO₂²⁺ →Fe²⁺ + HȮ₂                     k_i1

i2.  FeHO₂²⁺ + FeOH²⁺ → 2 Fe²⁺ + H₂O + O₂      k_i2

i3.  FeHO₂²⁺ + H₂O₂ → Fe²⁺ + H₂O + O₂ + ȮH     k_i3

Chain extension reactions

Fe²⁺ + H₂O₂ → Fe³⁺ + OH⁻ + ȮH k₁ ȮH + H₂O₂ → H₂O + HȮ₂ k₂ 2 Fe³⁺ + Ȯ₂⁻ → Fe²⁺  + O₂           k₃

Chain termination reactions

Fe²⁺ + HȮ₂ → Fe³⁺ + HO₂⁻ k₄ Fe²⁺ + ȮH → Fe³⁺ + OH⁻ k₅ HȮ₂ + HȮ₂ → H₂O₂ + O₂ k₆

6’  HȮ₂ + Ȯ₂⁻ →  HO₂⁻ + O₂      k_6’

Reviewer 1 wrote:

Line 284 to 298: check if the charge is balanced in the chemical equations.

Authors response:We corrected:

Equilibrium transformations

Fe³⁺ ↔ FeOH²⁺ + H⁺ K_I

II  Fe³⁺ + H₂O₂ ↔ FeHO₂²⁺ + H⁺     K_II

III. HȮ₂ ↔ H⁺ + Ȯ₂⁻                K_III

Initiation reactions

i1.  FeHO₂²⁺ →Fe²⁺ + HȮ₂                     k_i1

i2.  FeHO₂²⁺ + FeOH²⁺ → 2 Fe²⁺ + H₂O + O₂      k_i2

i3.  FeHO₂²⁺ + H₂O₂ → Fe²⁺ + H₂O + O₂ + ȮH     k_i3

Chain extension reactions

Fe²⁺ + H₂O₂ → Fe³⁺ + OH⁻ + ȮH k₁ ȮH + H₂O₂ → H₂O + HȮ₂ k₂ 2 Fe³⁺ + Ȯ₂⁻ → Fe²⁺  + O₂           k₃

Chain termination reactions

Fe²⁺ + HȮ₂ → Fe³⁺ + HO₂⁻ k₄ Fe²⁺ + ȮH → Fe³⁺ + OH⁻ k₅ HȮ₂ + HȮ₂ → H₂O₂ + O₂ k₆

6’  HȮ₂ + Ȯ₂⁻ →  HO₂⁻ + O₂      k_6’

Reviewer 1 wrote:

A conclusion or section of future outlook should be added.

Authors response:We added conclusions.

Point-by-point responses to Reviewer 1

 

We thank Reviewer 1 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 1 wrote:

Comments and Suggestions for Authors

Shul’pin presented a review manuscript on the metal complexes containing redox-active ligands in oxidation of hydrocarbons and alcohols. The manuscript is generally well-prepared and requires only minor revision.

 

Points to revise:

Line 88: “such as, for example” are redundant.

Authors response: We removed “for example”

Reviewer 1 wrote:

Line 91: intransitive metal complexes?

Authors response: Should be: complexes of non-transition metals

Reviewer 1 wrote:

Some errors in Figure 3

Authors response: we corrected

Reviewer 1 wrote:

Line 190: “The complexes include two ammonia molecules. X-Ray diffraction analysis showed that one of the ammonia molecules acts as a ligand, and the other forms an ammonium cation.” I think the first sentence is incorrect. There are one ammonia ligand and one ammonium cation!

Authors response: we corrected and wrote:

The complexes include two ammonia molecules. X-Ray diffraction analysis showed that there are one ammonia ligand and one ammonium cation.[37a,b] one of the ammonia molecules acts as a ligand, and the other forms an ammonium cation.

Reviewer 1 wrote:

Line 285: The charge is not balanced in the chemical equation.

Authors response:We corrected:

Equilibrium transformations

Fe³⁺ ↔ FeOH²⁺ + H⁺ K_I

II  Fe³⁺ + H₂O₂ ↔ FeHO₂²⁺ + H⁺     K_II

III. HȮ₂ ↔ H⁺ + Ȯ₂⁻                K_III

Initiation reactions

i1.  FeHO₂²⁺ →Fe²⁺ + HȮ₂                     k_i1

i2.  FeHO₂²⁺ + FeOH²⁺ → 2 Fe²⁺ + H₂O + O₂      k_i2

i3.  FeHO₂²⁺ + H₂O₂ → Fe²⁺ + H₂O + O₂ + ȮH     k_i3

Chain extension reactions

Fe²⁺ + H₂O₂ → Fe³⁺ + OH⁻ + ȮH k₁ ȮH + H₂O₂ → H₂O + HȮ₂ k₂ 2 Fe³⁺ + Ȯ₂⁻ → Fe²⁺  + O₂           k₃

Chain termination reactions

Fe²⁺ + HȮ₂ → Fe³⁺ + HO₂⁻ k₄ Fe²⁺ + ȮH → Fe³⁺ + OH⁻ k₅ HȮ₂ + HȮ₂ → H₂O₂ + O₂ k₆

6’  HȮ₂ + Ȯ₂⁻ →  HO₂⁻ + O₂      k_6’

Reviewer 1 wrote:

Line 284 to 298: check if the charge is balanced in the chemical equations.

Authors response:We corrected:

Equilibrium transformations

Fe³⁺ ↔ FeOH²⁺ + H⁺ K_I

II  Fe³⁺ + H₂O₂ ↔ FeHO₂²⁺ + H⁺     K_II

III. HȮ₂ ↔ H⁺ + Ȯ₂⁻                K_III

Initiation reactions

i1.  FeHO₂²⁺ →Fe²⁺ + HȮ₂                     k_i1

i2.  FeHO₂²⁺ + FeOH²⁺ → 2 Fe²⁺ + H₂O + O₂      k_i2

i3.  FeHO₂²⁺ + H₂O₂ → Fe²⁺ + H₂O + O₂ + ȮH     k_i3

Chain extension reactions

Fe²⁺ + H₂O₂ → Fe³⁺ + OH⁻ + ȮH k₁ ȮH + H₂O₂ → H₂O + HȮ₂ k₂ 2 Fe³⁺ + Ȯ₂⁻ → Fe²⁺  + O₂           k₃

Chain termination reactions

Fe²⁺ + HȮ₂ → Fe³⁺ + HO₂⁻ k₄ Fe²⁺ + ȮH → Fe³⁺ + OH⁻ k₅ HȮ₂ + HȮ₂ → H₂O₂ + O₂ k₆

6’  HȮ₂ + Ȯ₂⁻ →  HO₂⁻ + O₂      k_6’

Reviewer 1 wrote:

A conclusion or section of future outlook should be added.

Authors response:We added conclusions.

Point-by-point responses to Reviewer 1

 

We thank Reviewer 1 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 1 wrote:

Comments and Suggestions for Authors

Shul’pin presented a review manuscript on the metal complexes containing redox-active ligands in oxidation of hydrocarbons and alcohols. The manuscript is generally well-prepared and requires only minor revision.

 

Points to revise:

Line 88: “such as, for example” are redundant.

Authors response: We removed “for example”

Reviewer 1 wrote:

Line 91: intransitive metal complexes?

Authors response: Should be: complexes of non-transition metals

Reviewer 1 wrote:

Some errors in Figure 3

Authors response: we corrected

Reviewer 1 wrote:

Line 190: “The complexes include two ammonia molecules. X-Ray diffraction analysis showed that one of the ammonia molecules acts as a ligand, and the other forms an ammonium cation.” I think the first sentence is incorrect. There are one ammonia ligand and one ammonium cation!

Authors response: we corrected and wrote:

The complexes include two ammonia molecules. X-Ray diffraction analysis showed that there are one ammonia ligand and one ammonium cation.[37a,b] one of the ammonia molecules acts as a ligand, and the other forms an ammonium cation.

Reviewer 1 wrote:

Line 285: The charge is not balanced in the chemical equation.

Authors response:We corrected:

Equilibrium transformations

Fe³⁺ ↔ FeOH²⁺ + H⁺ K_I

II  Fe³⁺ + H₂O₂ ↔ FeHO₂²⁺ + H⁺     K_II

III. HȮ₂ ↔ H⁺ + Ȯ₂⁻                K_III

Initiation reactions

i1.  FeHO₂²⁺ →Fe²⁺ + HȮ₂                     k_i1

i2.  FeHO₂²⁺ + FeOH²⁺ → 2 Fe²⁺ + H₂O + O₂      k_i2

i3.  FeHO₂²⁺ + H₂O₂ → Fe²⁺ + H₂O + O₂ + ȮH     k_i3

Chain extension reactions

Fe²⁺ + H₂O₂ → Fe³⁺ + OH⁻ + ȮH k₁ ȮH + H₂O₂ → H₂O + HȮ₂ k₂ 2 Fe³⁺ + Ȯ₂⁻ → Fe²⁺  + O₂           k₃

Chain termination reactions

Fe²⁺ + HȮ₂ → Fe³⁺ + HO₂⁻ k₄ Fe²⁺ + ȮH → Fe³⁺ + OH⁻ k₅ HȮ₂ + HȮ₂ → H₂O₂ + O₂ k₆

6’  HȮ₂ + Ȯ₂⁻ →  HO₂⁻ + O₂      k_6’

Reviewer 1 wrote:

Line 284 to 298: check if the charge is balanced in the chemical equations.

Authors response:We corrected:

Equilibrium transformations

Fe³⁺ ↔ FeOH²⁺ + H⁺ K_I

II  Fe³⁺ + H₂O₂ ↔ FeHO₂²⁺ + H⁺     K_II

III. HȮ₂ ↔ H⁺ + Ȯ₂⁻                K_III

Initiation reactions

i1.  FeHO₂²⁺ →Fe²⁺ + HȮ₂                     k_i1

i2.  FeHO₂²⁺ + FeOH²⁺ → 2 Fe²⁺ + H₂O + O₂      k_i2

i3.  FeHO₂²⁺ + H₂O₂ → Fe²⁺ + H₂O + O₂ + ȮH     k_i3

Chain extension reactions

Fe²⁺ + H₂O₂ → Fe³⁺ + OH⁻ + ȮH k₁ ȮH + H₂O₂ → H₂O + HȮ₂ k₂ 2 Fe³⁺ + Ȯ₂⁻ → Fe²⁺  + O₂           k₃

Chain termination reactions

Fe²⁺ + HȮ₂ → Fe³⁺ + HO₂⁻ k₄ Fe²⁺ + ȮH → Fe³⁺ + OH⁻ k₅ HȮ₂ + HȮ₂ → H₂O₂ + O₂ k₆

6’  HȮ₂ + Ȯ₂⁻ →  HO₂⁻ + O₂      k_6’

Reviewer 1 wrote:

A conclusion or section of future outlook should be added.

Authors response:We added conclusions.

 

Reviewer 2 Report

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

 

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

 

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

 

Lines 91 and following

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

 

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

 

Line 173

I would specify platinum “(IV)” chloride

 

Lines 173 and following

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

 

 Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

 

Line 362

Caption to Figure 8 could use a more descriptive text.

 

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author Response

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.

Point-by-point responses to Reviewer-2

We thank Reviewer 2 for his / her / comments and suggestions which allowed us to improve the manuscript.

Reviewer 2 wrote:

Comments and Suggestions for Authors

I have been asked to review the manuscript entitled “Metal Complexes Containing Redox-active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review”. This is a review dealing with the oxidation of hydrocarbons, notably non-activated and generally not very reactive substrates, using metal complexes featuring non-innocent ligands.

It is my opinion that the manuscript is a meaningful contribution, it is generally well-presented (a few improvements are suggested though) and could be of interest for the readership of Catalysts.

There is however one aspect that does not go unnoticed (and to be fair the authors make no mystery of it at all, stating it plainly at the end of the abstract), i.e. that more than half of the 110 suggested references are from the authors themselves, making this manuscript more a sort of “Accounts of chemical research”-type contribution. Generally, this is not advisable in a review manuscript, unless, this being the case, the authors have dedicated their career, or a significant portion of it, to the topic under discussion and it is understood that the goal of the manuscript is primarily to review and systematize their own work.

In a sense, I feel the manuscript could be more fitting if labelled as a perspective-type contribution rather than a review (where one expects all advancements to be equally represented).

I would like to say that the authors managed to provide an account of their expertise, fully contextualized in the framework of existing literature, which I found quite readable: it is not uncommon for scientists who are very experienced on a topic to end up being a bit obscure to less experienced readers; current manuscript instead is accessible also to Readers with different backgrounds.

Let me come to text-specific comments.

Author’s response:

 we realized that this manuscript is not a comprehensive review (like reviews in Chemical Reviews) but it is a relatively survey.

As it was mentioned in the Abstract that the authors focused the attention on the own investigations.

Reviewer 2 wrote:

Abstract

While the first part of the abstract is clear and concise, the second half is more difficult to follow, and it refers to the whole of the content of the manuscript while loosely following the chosen paragraph subdivision. I would suggest trying to synthesize these in 1-2 concepts per discussed paragraph following their appearance order if possible.

Author’s response:

We corrected the second part of the Abstract.

Reviewer 2 wrote:

Lines 89-90

“Unlike transition metals, which can be present in compounds in various oxidation states, non-transition metals, as a rule, have one oxidation state.”

While I understand the message of the authors, oxidation states of non-transition metals are not always set in stone (although, surely, some are far more likely than others). I would suggest stating this concept in a less absolute way

Author’s response:

we added the following sentence. (although, surely, non-transition metals can have a few different oxidation states)

We also added to Conclusions the following sentence: “Only due to redox-active ligands are mechanisms of generation of free radicals from peroxides realized with the participation of metal ions, without changing their valence state”.

Reviewer 2 wrote:

Lines 91

“intransitive” is at times used to designate non-transition metals. This terminology is not frequently found, perhaps sticking to “non-transition” or “main-group metals” would be advisable.

Author’s response:

We corrected

Reviewer 2 wrote:

Line 102

“Di Stefano” is correctly referenced in the text, but not so in ref 24, where he appears as “Stefano, D.”

Author’s response:

We corrected

Line 173

I would specify platinum “(IV)” chloride

Author’s response:

We corrected

Reviewer 2 wrote:

 Lines 173

Previous work by the authors is discussed. I would ask the authors to give more precise literature references within the text in this section (e.g. for lines 173-174 one expects a reference, the same goes for lines 190 and 191 where results of X-ray analysis are discussed, and so on).

Author’s response:

we added a few references (marked by yellow background in the text and list of references)

Reviewer 2 wrote:

Line 350

“has a noticeably higher (?) compared with”.

A concept (most likely energy barrier/activation energy) is missing here.

Author’s response:

see. Ref. 76: “Our calculations show that direct transfer has a higher barrier than pca assisted

indirect transfer.” 

Reviewer 2 wrote:

Line 362

Caption to Figure 8 could use a more descriptive text.

Author’s response

we modified the caption to fig. 8

Reviewer 2 wrote:

Line 414

Why are we lacking conclusions?

I found the introductory part fresh and agreeable. I think we deserve to have an ending which is in line with the premise (although it is clear that this remains an open field).

Author’s response:

We added a few lines of the conclusions.