Synthesis, Properties and Applications of Lanthanide and Actinide Molecular Compounds

A special issue of Inorganics (ISSN 2304-6740). This special issue belongs to the section "Coordination Chemistry".

Deadline for manuscript submissions: closed (31 July 2023) | Viewed by 21080

Special Issue Editors


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Guest Editor
Centro de Química Estrutural (CQE), Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 2695-066 Bobadela LRS, Portugal
Interests: f-block chemistry; redox reactivity; metal-ligand multiple bonding; small molecule activation

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Guest Editor
Centro de Química Estrutural (CQE), Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 2695-066 Bobadela LRS, Portugal
Interests: f-block chemistry; gas-phase ion chemistry; mass spectrometry; radiochemistry

Special Issue Information

Dear Colleagues,

Five years have elapsed since Inorganics published a Special Issue devoted to "Rare Earth and Actinide Complexes", with Stephen Mansell and Stephen Liddle as Guest Editors. In the years that have followed, significant advancements occurred, with highlights that include the extension to the +4 oxidation state of praseodymium and terbium molecular compounds, high-temperature dysprosium-based single-molecule magnets, new patterns of reactivity of thorium and uranium complexes and new insights into covalency/electronic structure trends in the f-block. Developments in the synthesis of molecular compounds of heavier actinides, which are important from a fundamental viewpoint as well as in the nuclear field, have also recently emerged. Theoretical chemistry tools, supported by increasing computational resources, continue to play a crucial role in classifying bonding interactions and assessing the reactivity of f-element molecular compounds. Lanthanides and actinides have unique physical and chemical properties that result in a wide variety of applications, from energy production to life sciences. Owing to the unique electronic, optical and magnetic properties of lanthanide ions, the potential utility of molecular lanthanide compounds in biosensing and bioimaging continues to increase. The search for new bonding motifs in molecular actinide compounds is an ongoing challenge and is of importance in the development of separation strategies for used nuclear fuel and radioactive waste processing. This Special Issue aims to collect contributions focused on recent research on synthesis, reactivity, properties and applications, such as catalysis, materials and medicine, of lanthanide and actinide molecular compounds. We expect that it will contribute to the development of f-element chemistry, and we invite you to participate with your more recent work.

Dr. Leonor Maria
Dr. Joaquim Marçalo
Guest Editors

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Keywords

  • coordination and organometallic chemistry
  • reactivity and catalysis
  • theory and physical properties
  • technological and nuclear applications
  • biological and medical applications

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Published Papers (9 papers)

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Research

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16 pages, 8666 KiB  
Article
Understanding the Selective Extraction of the Uranyl Ion from Seawater with Amidoxime-Functionalized Materials: Uranyl Complexes of Pyrimidine-2-amidoxime
by Sokratis T. Tsantis, Zoi G. Lada, Sotiris G. Skiadas, Demetrios I. Tzimopoulos, Catherine P. Raptopoulou, Vassilis Psycharis and Spyros P. Perlepes
Inorganics 2024, 12(3), 82; https://doi.org/10.3390/inorganics12030082 - 7 Mar 2024
Cited by 1 | Viewed by 1929
Abstract
The study of small synthetic models for the highly selective removal of uranyl ions from seawater with amidoxime-containing materials is a valuable means to enhance their recovery capacity, leading to better extractants. An important issue in such efforts is to design bifunctional ligands [...] Read more.
The study of small synthetic models for the highly selective removal of uranyl ions from seawater with amidoxime-containing materials is a valuable means to enhance their recovery capacity, leading to better extractants. An important issue in such efforts is to design bifunctional ligands and study their reactions with trans-{UO2}2+ in order to model the reactivity of polymeric sorbents possessing both amidoximate and another adjacent donor site on the side chains of the polymers. In this work, we present our results concerning the reactions of uranyl and pyrimidine-2-amidoxime, a ligand possessing two pyridyl nitrogens near the amidoxime group. The 1:2:2 {UO2}2+/pmadH2/external base (NaOMe, Et3N) reaction system in MeOH/MeCN provided access to complex [UO2(pmadH)2(MeOH)2] (1) in moderate yields. The structure of the complex was determined by single-crystal X-ray crystallography. The UVI atom is in a distorted hexagonal bipyramidal environment, with the two oxo groups occupying the trans positions, as expected. The equatorial plane consists of two terminal MeOH molecules at opposite positions and two N,O pairs of two deprotonated η2 oximate groups from two 1.11000 (Harris notation) pmadH ligands; the two pyridyl nitrogen atoms and the –NH2 group remain uncoordinated. One pyridyl nitrogen of each ligand is the acceptor of one strong intramolecular H bond, with the donor being the coordinated MeOH oxygen atom. Non-classical Caromatic-H⋯X (X=O, N) intermolecular H bonds and π–π stacking interactions stabilize the crystal structure. The complex was characterized by IR and Raman spectroscopies, and the data were interpreted in terms of the known structure of 1. The solid-state structure of the complex is not retained in DMSO, as proven via 1H NMR and UV/Vis spectroscopic techniques as well as molar conductivity data, with the complex releasing neutral pmadH2 molecules. The to-date known coordination chemistry of pmadH2 is critically discussed. An attempt is also made to discuss the technological implications of this work. Full article
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15 pages, 2064 KiB  
Article
The Synthesis, Crystal Structure, and Magnetic Properties of Mono-Scorpionate Eu(III) Complexes
by Kira E. Vostrikova, Taisiya S. Sukhikh and Alexander N. Lavrov
Inorganics 2023, 11(10), 418; https://doi.org/10.3390/inorganics11100418 - 23 Oct 2023
Cited by 1 | Viewed by 1687
Abstract
Three Eu3+ complexes containing a neutral tripodal ligand possessing a predictable coordination mode have been obtained and studied. The trispyrazolylmethane complexes have an aqua ligand in the coordination sphere, forming both the mononuclear species [Eu(HCPz3)H2O(NO3)3 [...] Read more.
Three Eu3+ complexes containing a neutral tripodal ligand possessing a predictable coordination mode have been obtained and studied. The trispyrazolylmethane complexes have an aqua ligand in the coordination sphere, forming both the mononuclear species [Eu(HCPz3)H2O(NO3)3] and the dimer [Eu(HCPz3)H2O(CF3SO3)3]2, having a Chinese lantern structure, whereas the use of the methylated tripod leads to the water-free complex, [Eu(HC(PzMe2)3)(NO3)3]. A qualitative analysis of the magnetic susceptibility of polycrystalline samples demonstrated that the magnetic properties can be described using a simple Van Vleck formula with spin–orbit coupling parameter (λ = 383 ÷ 406 cm−1) close to the values for free Eu3+ ions. The stereochemical analysis of the coordination environment of [Ln(HC(PzMe2)3)(NO3)3] has shown that these complexes can be used as diamagnetic model systems to obtain information on the crystal field effects in the paramagnetic monoradical complexes, [LnRad(NO3)3], since both types of compounds have the same type of coordination polyhedron (symmetry point group D3h) and very close Ln–donor atom distances. Full article
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13 pages, 5221 KiB  
Article
Photoluminescent Lanthanide(III) Coordination Polymers with Bis(1,2,4-Triazol-1-yl)Methane Linker
by Elizaveta A. Ivanova, Ksenia S. Smirnova, Ivan P. Pozdnyakov, Andrei S. Potapov and Elizaveta V. Lider
Inorganics 2023, 11(8), 317; https://doi.org/10.3390/inorganics11080317 - 27 Jul 2023
Cited by 7 | Viewed by 1463
Abstract
A series of new lanthanide(III) coordination polymers with the general formula [Ln(btrm)2(NO3)3]n, where btrm = bis(1,2,4-triazol-1-yl)methane and Ln = Eu3+, Tb3+, Sm3+, Dy3+, Gd3+ were synthesized [...] Read more.
A series of new lanthanide(III) coordination polymers with the general formula [Ln(btrm)2(NO3)3]n, where btrm = bis(1,2,4-triazol-1-yl)methane and Ln = Eu3+, Tb3+, Sm3+, Dy3+, Gd3+ were synthesized and characterized by IR-spectroscopy, elemental, thermogravimetric, single-crystal, and powder X-ray diffraction analyses. Europium(III), samarium(III), terbium(III), and gadolinium(III) coordination polymers demonstrate thermal stability up to 250 °C, while dysprosium(III) is stable up to 275 °C. According to single-crystal X-ray diffraction analysis, the ligand exhibits a bidentate-bridging coordination mode, forming a polymeric chain of octagonal metallocycles. The photoluminescence of the free ligand in the polycrystalline state is observed in the ultraviolet range with a quantum yield of 13%. The energy transfer from the ligand to the lanthanide ions was not observed for all obtained coordination polymers. However, there are sharp bands of lanthanide(III) ions in the diffuse reflectance and excitation spectra of the obtained compounds. Therefore, Ln(III) luminescence arises, most probably, from the enhancement of f-f transition intensity under the influence of the ligand field and non-centrosymmetric interactions. Full article
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15 pages, 1551 KiB  
Article
Tetramethylcyclopentadienyl Samarium(II) Metallocene Chemistry: Isolation of a Bimetallic Sm(II)/Sm(II) Complex
by Joseph Q. Nguyen, Joseph W. Ziller and William J. Evans
Inorganics 2023, 11(1), 4; https://doi.org/10.3390/inorganics11010004 - 21 Dec 2022
Cited by 1 | Viewed by 2136
Abstract
The salt metathesis reaction between one equivalent of SmI2(THF)2 and two equivalents of K(C5Me4H) in THF afforded single crystals of the unusual, toluene-soluble, and asymmetric bimetallic Sm(II)/Sm(II) complex, (C5Me4H)2SmII [...] Read more.
The salt metathesis reaction between one equivalent of SmI2(THF)2 and two equivalents of K(C5Me4H) in THF afforded single crystals of the unusual, toluene-soluble, and asymmetric bimetallic Sm(II)/Sm(II) complex, (C5Me4H)2SmII(μ-η35-C5Me4H)SmII(C5Me4H)(THF)2, instead of the expected product, (C5Me4H)2SmII(THF)2. The toluene-insoluble products of this reaction can be worked up in 1,2-dimethoxyethane (DME) to provide X-ray quality crystals of the monomeric Sm(II) metallocene, (C5Me4H)2SmII(DME). (C5Me4H)2SmII(DME) can also be synthesized directly by the reaction between one equivalent of SmI2(THF)2 and two equivalents of K(C5Me4H) in neat DME. The isolation and characterization of the bimetallic Sm(II)/Sm(II) complex provides supporting evidence for the possible oligomerization that may occur during the synthesis of Sm(II) complexes with cyclopentadienyl ligands that are less sterically bulky and less solubilizing than (C5Me5)1−. Full article
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8 pages, 7056 KiB  
Communication
Magnetocaloric Effect of Two Gd-Based Frameworks
by Bo-Liang Liu, Qiao-Fei Xu, La-Sheng Long and Lan-Sun Zheng
Inorganics 2022, 10(7), 91; https://doi.org/10.3390/inorganics10070091 - 25 Jun 2022
Cited by 1 | Viewed by 2287
Abstract
Magnetic refrigeration material is the key to adiabatic demagnetization refrigeration technology. In this work, two magnetic refrigerants, Gd5(C4O4)(HCOO)3(CO3)2(OH)6·2.5H2O (1) and Gd2(OH)4SO [...] Read more.
Magnetic refrigeration material is the key to adiabatic demagnetization refrigeration technology. In this work, two magnetic refrigerants, Gd5(C4O4)(HCOO)3(CO3)2(OH)6·2.5H2O (1) and Gd2(OH)4SO4 (2), were prepared through hydrothermal reaction. Magnetic study reveals that their magnetic entropy changes are 24.8 J kg−1 K−1 for 1 and 15.1 J kg−1 K−1 for 2 at 2 K and 2 T, respectively. The magnetic entropy changes of 1 and 2 at T = 2 K and ∆H = 2 T exceed most gadolinium hydroxyl compounds, indicating that magnetic refrigerants with large magnetic entropy changes at low magnetic fields can be obtained by introducing more weak magnetic exchange ligands to replace hydroxyl groups in gadolinium hydroxyl compounds. Full article
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9 pages, 1950 KiB  
Article
Reactivity of a Sterical Flexible Pentabenzylcyclopentadienyl Samarocene
by Niklas Reinfandt and Peter W. Roesky
Inorganics 2022, 10(2), 25; https://doi.org/10.3390/inorganics10020025 - 18 Feb 2022
Cited by 1 | Viewed by 2404
Abstract
Reactivity studies of the classical divalent lanthanide compound [CpBz52Sm] (CpBz5 = pentabenzylcyclopentadienyl-anion) towards diphenyl dichalcogenides and d-element carbonyl complexes led to remarkable results. In the compounds obtained, a different number of Sm-C(phenyl) interactions and differently oriented benzyl groups were [...] Read more.
Reactivity studies of the classical divalent lanthanide compound [CpBz52Sm] (CpBz5 = pentabenzylcyclopentadienyl-anion) towards diphenyl dichalcogenides and d-element carbonyl complexes led to remarkable results. In the compounds obtained, a different number of Sm-C(phenyl) interactions and differently oriented benzyl groups were observed, suggesting—despite the preference of these interactions in [CpBz52Sm] described in previous studies—a flexible orientation of the benzyl groups and thus a variable steric shielding of the metal center by the ligand. The obtained compounds are either present as monometallic complexes (reduction of the dichalcogenides) or tetrametallic bridged compounds in the case of the d/f-element carbonyl complexes. Full article
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10 pages, 5240 KiB  
Communication
Tripodal Oxazolidine-N-Oxyl Diradical Complexes of Dy3+ and Eu3+
by Philippe Rey, Andrea Caneschi, Taisiya S. Sukhikh and Kira E. Vostrikova
Inorganics 2021, 9(12), 91; https://doi.org/10.3390/inorganics9120091 - 20 Dec 2021
Cited by 4 | Viewed by 2796
Abstract
Two diradical complexes of the formula [LnRad2(CF3SO3)3] c (Ln(III) = Dy, Eu, Rad = 4,4-dimethyl-2,2-bis(pyridin-2-yl)-1,3-oxazolidine-3-oxyl) were obtained in air conditions. These are the first examples of diradical compounds of lanthanides and oxazolidine nitroxide. The complexes [...] Read more.
Two diradical complexes of the formula [LnRad2(CF3SO3)3] c (Ln(III) = Dy, Eu, Rad = 4,4-dimethyl-2,2-bis(pyridin-2-yl)-1,3-oxazolidine-3-oxyl) were obtained in air conditions. These are the first examples of diradical compounds of lanthanides and oxazolidine nitroxide. The complexes were characterized crystallographically and magnetically. Single crystal XRD analysis revealed that their coordination sphere is composed of three monodentate triflates and two tripodal Rad, which coordinate the central atom in a tridentate manner via two N atoms of the pyridine groups and the O atom of a nitroxide group. The LnO5N4 polyhedron represents a spherical capped square antiprism with point symmetry close to C4v. The data of static magnetic measurements are compatible with the presence of two paramagnetic ligands in the coordination sphere of the metal. Full article
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Review

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29 pages, 50063 KiB  
Review
The Tripodal Ligand’s 4f Complexes: Use in Molecular Magnetism
by Kira E. Vostrikova
Inorganics 2023, 11(7), 307; https://doi.org/10.3390/inorganics11070307 - 20 Jul 2023
Cited by 3 | Viewed by 1603
Abstract
A predictable type of coordination is a key property of tripodal ligands. Homo- and heteroleptic lanthanide complexes with tripodal ligands are a representative class of compounds. However, despite the fact that many of them are paramagnetic, their magnetic behavior is poorly studied. This [...] Read more.
A predictable type of coordination is a key property of tripodal ligands. Homo- and heteroleptic lanthanide complexes with tripodal ligands are a representative class of compounds. However, despite the fact that many of them are paramagnetic, their magnetic behavior is poorly studied. This is because their photophysical and catalytic properties are considered more attractive. In the present review, we try to summarize the available structural information and only a few examples of data on magnetic properties in order to draw some conclusions about the prospect of such ligands in the design of quantum molecular magnets involving lanthanide (Ln) ions. We would also like to catch the reader’s attention to the fact that, despite the consideration of a large part of the currently known Ln compounds with tripodal ligands, this review is not exhaustive. However, our goal is to draw the attention of magnetochemists and theoreticians to a whole niche of air-stable Ln complexes that is still out of their field of vision. Full article
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27 pages, 7927 KiB  
Review
Uranyl Analogue Complexes—Current Progress and Synthetic Challenges
by Leonor Maria and Joaquim Marçalo
Inorganics 2022, 10(8), 121; https://doi.org/10.3390/inorganics10080121 - 18 Aug 2022
Cited by 4 | Viewed by 2688
Abstract
Uranyl ions, {UO2}n+ (n = 1, 2), display trans, strongly covalent, and chemically robust U-O multiple bonds, where 6d, 5f, and 6p orbitals play important roles. The synthesis of isoelectronic analogues of uranyl has been of interest for quite [...] Read more.
Uranyl ions, {UO2}n+ (n = 1, 2), display trans, strongly covalent, and chemically robust U-O multiple bonds, where 6d, 5f, and 6p orbitals play important roles. The synthesis of isoelectronic analogues of uranyl has been of interest for quite some time, mainly with the purpose of unveiling covalence and 5f-orbital participation in bonding. Significant advances have occurred in the last two decades, initially marked by the synthesis of uranium(VI) bis(imido) complexes, the first analogues with a {RNUNR}2+ core, later followed by the synthesis of unique trans-{EUO}2+ (E = S, Se) complexes, and recently highlighted by the synthesis of the first complexes featuring a linear {NUN} moiety. This review covers the synthesis, structure, bonding, and reactivity of uranium complexes containing a linear {EUE}n+ core (n = 0, 1, 2), isoelectronic to uranyl ions, {OUO}n+ (n = 1, 2), incorporating σ- and π-donating ligands that can engage in uranium–ligand multiple bonding, where oxygen may be replaced by heavier chalcogenido, imido, nitride, and carbene ligands, or by a transition metal. It focuses on synthetic methods of well-defined molecular uranium species in the condensed phase but also references gas-phase and low-temperature-matrix experiments, as well as computational studies that may lead to valuable insights. Full article
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