Crystals

Research

12 pages, 2230 KiB

Open AccessArticle

Dinuclear Molybdenum(VI) Complexes Based on Flexible Succinyl and Adipoyl Dihydrazones

by Edi Topić, Vladimir Damjanović, Katarina Pičuljan and Mirta Rubčić

Crystals 2024, 14(2), 135; https://doi.org/10.3390/cryst14020135 - 29 Jan 2024

Viewed by 1298

A series of molybdenum(VI) complexes with aryl-functionalized alkyl dihydrazones was prepared by the reaction of [MoO₂(acac)₂] and the appropriate dihydrazone in methanol. Their solid-state structures were elucidated via single-crystal X-ray diffraction (SC-XRD) and Fourier-transform infra-red (FTIR) spectroscopy, while the [...] Read more.

A series of molybdenum(VI) complexes with aryl-functionalized alkyl dihydrazones was prepared by the reaction of [MoO₂(acac)₂] and the appropriate dihydrazone in methanol. Their solid-state structures were elucidated via single-crystal X-ray diffraction (SC-XRD) and Fourier-transform infra-red (FTIR) spectroscopy, while the thermal stability of compounds was inspected by combined thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) experiments. The behaviour of complexes in DMSO-d₆ solution was explored by nuclear magnetic resonance (NMR). The relevant data show that all complexes are dinuclear, with dihydrazones acting as ditopic hexadentate ligands. The in vitro cytotoxic activity of the prepared molybdenum(VI) complexes was evaluated on THP-1 and HepG2 cell lines, while their antibacterial activity was tested against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Moraxella catarrhalis bacteria. The majority of compounds proved to be non-cytotoxic, while some exhibited superior antibacterial activity in comparison to dihydrazone ligands. Full article

(This article belongs to the Special Issue The Polyhedral Face of Coordination Chemistry)

► Show Figures

Graphical abstract

14 pages, 2900 KiB

Open AccessArticle

New Polynuclear Coordination Compounds Based on 2–(Carboxyphenyl)iminodiacetate Anion: Synthesis and X-rays Crystal Structures

by Sebastián Martínez, Carlos Kremer, Javier González-Platas and Carolina Mendoza

Crystals 2023, 13(12), 1669; https://doi.org/10.3390/cryst13121669 - 9 Dec 2023

Cited by 1 | Viewed by 1119

Abstract

In the present work, novel polymeric copper(II) coordination compounds, namely [Cu₂(cpida)(H₂O)₄][Cu(cpida)]·3H₂O (1) (cpida³⁻ = 2-(carboxyphenyl)iminodiacetate anion) and Na[Cu(cpida)] (3), were synthesized and characterized using infrared spectroscopy, thermogravimetric analysis, elemental analysis, [...] Read more.

In the present work, novel polymeric copper(II) coordination compounds, namely [Cu₂(cpida)(H₂O)₄][Cu(cpida)]·3H₂O (1) (cpida³⁻ = 2-(carboxyphenyl)iminodiacetate anion) and Na[Cu(cpida)] (3), were synthesized and characterized using infrared spectroscopy, thermogravimetric analysis, elemental analysis, and single-crystal X-ray diffraction. Compound 1 was obtained by slowly evaporating an aqueous solution of H₃cpida, copper(II) sulfate, and NaOH at room temperature. The structural characterization revealed that 1 is an ionic entity formed by the [Cu(cpida)]⁻ anion and the [Cu₂(cpida)(H₂O)₄]⁺ cation, both of polymeric 1D structure. Compound 3 was prepared under similar conditions from copper perchlorate and crystallized via acetone diffusion. It is a coordination polymer formed by the [Cu(cpida)]⁻ units, and the sodium cation is present in the structure, counterbalancing the anion charge. Depending on the crystallization conditions, it was possible to obtain other solvation forms of these structures. Starting from the conditions of compound 1, via the diffusion of ethanol, [Cu₂(cpida)(H₂O)₄][Cu(cpida)]·H₂O·1/2EtOH (2) was precipitated, while a hydrate form of compound 3 with the formula Na[Cu(cpida)]·2H₂O (4) was obtained via methanol diffusion. Full article

(This article belongs to the Special Issue The Polyhedral Face of Coordination Chemistry)

► Show Figures

Figure 1

16 pages, 1469 KiB

Open AccessArticle

Sulfonato Complex Formation Rather than Sulfonate Binding in the Extraction of Base Metals with 2,2′-Biimidazole: Extraction and Complexation Studies

by Pulleng Moleko-Boyce, Eric C. Hosten and Zenixole R. Tshentu

Crystals 2023, 13(9), 1350; https://doi.org/10.3390/cryst13091350 - 5 Sep 2023

Viewed by 1025

Abstract

The application of a bidentate aromatic N,N’-donor ligand, 2,2′-biimidazole (BIIMH₂), as an extractant in the form of 1-octyl-2,2′-biimidazole (OBIIMH) and related derivatives in the solvent extraction of base metal ions (Mg²⁺, Mn²⁺, Fe³⁺, Fe [...] Read more.

The application of a bidentate aromatic N,N’-donor ligand, 2,2′-biimidazole (BIIMH₂), as an extractant in the form of 1-octyl-2,2′-biimidazole (OBIIMH) and related derivatives in the solvent extraction of base metal ions (Mg²⁺, Mn²⁺, Fe³⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺) from an acidic sulfonate medium using dinonylnaphthalene disulfonic acid (DNNDSA) as a synergist was investigated. OBIIMH with DNNDSA as a co-extractant showed a lack of selectivity for base metals ions (Mg²⁺, Mn²⁺, Fe³⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺) despite its similarity with a related bidentate aromatic ligand, 2,2′-pyridylimidazole, which showed preference for Ni(II) ions. The nickel(II) specificity, through stereochemical “tailor-making”, was not achieved as expected and the extracted species were isolated to study the underlying chemistry. The homemade metal sulfonate salts, M(RSO₃)₂·6H₂O (R = Toluene and M²⁺ = Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺), were used as precursors of the metal complexes of BIIMH₂ using toluene-4-sulfonic acid as the representative sulfonate. Spectroscopic analysis and single-crystal X-ray analysis supported the formation of similar neutral distorted octahedral sulfonato complexes through the bis coordination of BIIMH₂ and two sulfonate ions rather than the formation of cationic complex species with anion coordination of sulfonates. We attributed the observation of similar complex species and the similar stability constants of the bis-complexes in solution as the cause for the lack of pH-metric separation of the later 3d metal ions. Full article

(This article belongs to the Special Issue The Polyhedral Face of Coordination Chemistry)

► Show Figures

Figure 1

13 pages, 2567 KiB

Open AccessArticle

Transition Metals Meet Scorpiand-like Ligands

by Salvador Blasco, Begoña Verdejo, María Paz Clares and Enrique García-España

Crystals 2023, 13(9), 1338; https://doi.org/10.3390/cryst13091338 - 1 Sep 2023

Viewed by 1086

Abstract

Scorpiand-like ligands combine the preorganization of the donor atoms of macrocycles and the degrees of freedom of the linear ligands. We prepared the complexes of several of these ligands with transition metal ions and made a crystallographic and water solution speciation studies. The [...] Read more.

Scorpiand-like ligands combine the preorganization of the donor atoms of macrocycles and the degrees of freedom of the linear ligands. We prepared the complexes of several of these ligands with transition metal ions and made a crystallographic and water solution speciation studies. The analysis of the resulting crystal structures show that the ligands have the ability to accommodate several metal ions and that the coordination geometry is mostly determined by the ligand. Ligand 6-[3,7-diazaheptyl]-3,6,9–triaza-1-(2,6)-pyridinacyclodecaphane (L3) is an hexadentate ligand that affords a family of isostructural crystals with Cu(II), Mn(II), Ni(II) and Zn(II). The attempts to obtain Co(II) crystals afforded the Co(III) structures instead. Ligand 6-[4-(2-pyridyl)-3-azabutyl]-3,6,9-triaza-1(2,6)-pyridinacyclodecaphane (L2) is very similar to L3 and yields structures similar to it, but its behavior in solution is very different due to the different interaction with protons. Ligand 6-(2-aminoethyl)-3,6,9–triaza-1-(2,6)-pyridinacyclodecaphane (L1) is pentadentate and its complexes allow the metal to be more accessible from the solvent. A Zn(II) structure with L1 shows the species [ZnBrHL1]

^{2 +}

, which exists in a narrow pH range. Full article

(This article belongs to the Special Issue The Polyhedral Face of Coordination Chemistry)

► Show Figures

Figure 1

9 pages, 1615 KiB

Open AccessArticle

Synthesis, Structure, and Characterizations of a Heterobimetallic Heptanuclear Complex [Pb₂Co₅(acac)₁₄]

by Yuxuan Zhang, Zheng Wei and Evgeny V. Dikarev

Crystals 2023, 13(7), 1089; https://doi.org/10.3390/cryst13071089 - 12 Jul 2023

Viewed by 1096

Abstract

An unusual heterobimetallic volatile compound [Pb₂Co₅(acac)₁₄] was synthesized by the gas phase/solid-state technique. The preparation can be readily scaled up using the solution approach. X-ray powder diffraction, ICP-OES analysis, and DART mass spectrometry were engaged to confirm [...] Read more.

An unusual heterobimetallic volatile compound [Pb₂Co₅(acac)₁₄] was synthesized by the gas phase/solid-state technique. The preparation can be readily scaled up using the solution approach. X-ray powder diffraction, ICP-OES analysis, and DART mass spectrometry were engaged to confirm the composition and purity of heterobimetallic complex. The composition is unique among the large family of lead(tin): transition metal = 2:1, 1:1, and 1:2 β-diketonates compounds that are mostly represented by coordination polymers. The molecular structure of the complex was elucidated by synchrotron single crystal X-ray diffraction to reveal the unique heptanuclear moiety {Co(acac)₂[Pb(acac)₂-Co(acac)₂-Co(acac)₂]₂} built upon bridging interactions of acetylacetonate oxygens to neighboring metal centers that bring their coordination numbers to six. The appearance of unique heptanuclear assembly can be attributed to the fact that the [Co(acac)₂] units feature both cis- and trans-bis-bridging modes, making the polynuclear moiety rather flexible. This type of octahedral coordination is relatively unique among known lead(tin)-3d transition metal β-diketonates. Due to the high-volatility, [Pb₂Co₅(acac)₁₄] can be potentially applied as a MOCVD precursor for the low-temperature preparation of lead-containing functional materials. Full article

(This article belongs to the Special Issue The Polyhedral Face of Coordination Chemistry)

► Show Figures

Figure 1

13 pages, 2779 KiB

Open AccessEditor’s ChoiceArticle

Structural and Magnetic Properties of the {Cr(pybd)₃[Cu(cyclen)]₂}(BF₄)₄ Heteronuclear Complex

by Fabio Santanni, Laura Chelazzi, Lorenzo Sorace, Grigore A. Timco and Roberta Sessoli

Crystals 2023, 13(6), 901; https://doi.org/10.3390/cryst13060901 - 1 Jun 2023

Viewed by 1696

Abstract

Heterotopic ligands containing chemically different binding centers are appealing candidates for obtaining heteronuclear metal complexes. By exploiting this strategy, it is possible to introduce different paramagnetic centers characterized by specific anisotropic magnetic properties that make them distinguishable when weakly magnetically coupled. This molecular [...] Read more.

Heterotopic ligands containing chemically different binding centers are appealing candidates for obtaining heteronuclear metal complexes. By exploiting this strategy, it is possible to introduce different paramagnetic centers characterized by specific anisotropic magnetic properties that make them distinguishable when weakly magnetically coupled. This molecular approach has great potential to yield multi-spin adducts capable of mimicking logical architectures necessary for quantum information processing (QIP), i.e., quantum logic gates. A possible route for including a single-ion magnetic center within a finite-sized heterometallic compound uses the asymmetric (1-pyridyl)-butane-1,3-dione (pybd) ligand reported in the literature for obtaining Cr³⁺−Cu²⁺ metallo-cages. To avoid the formation of cages, we adopted the cyclen (1,4,7,10-tetraazacyclododecane) ligand as a “capping” agent for the Cu²⁺ ions. We report here the structural and magnetic characterization of the unprecedented adduct {Cr(pybd)₃[Cu(cyclen)]₂}(BF₄)₄, whose structure is characterized by a central Cr³⁺ ion in a distorted octahedral coordination environment and two peripheral Cu²⁺ ions with square-pyramidal coordination geometries. As highlighted by Continuous Wave Electron Paramagnetic Resonance (EPR) spectroscopy and Direct Current (DC) magnetometry measurements, this adduct shows negligible intramolecular magnetic couplings, and it maintains the characteristic EPR signals of Cr³⁺ and Cu²⁺ moieties when diluted in frozen solutions. Full article

(This article belongs to the Special Issue The Polyhedral Face of Coordination Chemistry)

► Show Figures

Figure 1

16 pages, 4915 KiB

Open AccessArticle

Anion Coordination into Ligand Clefts

by Matteo Savastano, Carlotta Cappanni, Carla Bazzicalupi, Cristiana Lofrumento and Antonio Bianchi

Crystals 2023, 13(5), 823; https://doi.org/10.3390/cryst13050823 - 16 May 2023

Cited by 1 | Viewed by 1166

Abstract

A tripodal anion receptor has been obtained by an easy and fast single-reaction synthesis from commercial reagents. The three ligand arms-bearing aromatic groups able to form anion–π interactions define ligand clefts where large anions, such as perchlorate and perrhenate, are included. We report [...] Read more.

A tripodal anion receptor has been obtained by an easy and fast single-reaction synthesis from commercial reagents. The three ligand arms-bearing aromatic groups able to form anion–π interactions define ligand clefts where large anions, such as perchlorate and perrhenate, are included. We report here the synthesis of the ligand, its acid/base properties in an aqueous solution which has been used to direct the synthesis of anion complexes, and the crystal structure of the free ligand and its anion complexes H₃L(ClO₄)₂·H₂O and H₃L(ReO₄)₂. Full article

(This article belongs to the Special Issue The Polyhedral Face of Coordination Chemistry)

► Show Figures

Graphical abstract

12 pages, 2400 KiB

Open AccessEditor’s ChoiceArticle

Functionalization and Coordination Effects on the Structural Chemistry of Pendant Arm Derivatives of 1,4,7-trithia-10-aza-cyclododecane ([12]aneNS₃)

by Claudia Caltagirone, Maria Carla Aragoni, Massimiliano Arca, Alexander John Blake, Francesco Demartin, Alessandra Garau, Enrico Podda, Alexandra Pop, Vito Lippolis and Cristian Silvestru

Crystals 2023, 13(4), 616; https://doi.org/10.3390/cryst13040616 - 3 Apr 2023

Viewed by 1469

Abstract

The effect of different pendant arms on the structural chemistry of the 1,4,7-trithia-10-aza-cyclododecane ([12]aneNS₃) macrocycle is discussed in relation to the coordination chemistry of all known functionalized derivatives of [12]aneNS₃, which have been structurally characterized. Full article

(This article belongs to the Special Issue The Polyhedral Face of Coordination Chemistry)

► Show Figures

Figure 1

13 pages, 1923 KiB

Open AccessArticle

Lanthanide(III) Complexes with Thiodiacetato Ligand: Chemical Speciation, Synthesis, Crystal Structure, and Solid-State Luminescence

by Julia Torres, Javier González-Platas and Carlos Kremer

Crystals 2023, 13(1), 56; https://doi.org/10.3390/cryst13010056 - 28 Dec 2022

Cited by 3 | Viewed by 1745

Abstract

The synthesis, crystal structures, and luminescence of two lanthanide polynuclear complexes with the general formula [Ln₂(tda)₃(H₂O)₅]·3H₂O (Ln = Sm, Eu; tda = thiodiacetato anion) are reported. The compounds were obtained by direct reaction [...] Read more.

The synthesis, crystal structures, and luminescence of two lanthanide polynuclear complexes with the general formula [Ln₂(tda)₃(H₂O)₅]·3H₂O (Ln = Sm, Eu; tda = thiodiacetato anion) are reported. The compounds were obtained by direct reaction of H₂tda and lanthanide(III) chloride in an aqueous solution. The choice of the conditions of synthesis was based on speciation studies. The structure of the polymeric complexes contains Ln(III) ions in a tricapped trigonal prism geometry. The versatility of this ligand provides different coordination modes and provokes the formation of thick 2D sheets. Direct excitation of the Ln(III) ions gives place to the characteristic intra-configuration sharp luminescence emission of both complexes in the solid state. Full article

(This article belongs to the Special Issue The Polyhedral Face of Coordination Chemistry)

► Show Figures

Graphical abstract

14 pages, 2019 KiB

Open AccessArticle

Molecular Structures of the Pyridine-2-olates PhE(pyO)₃ (E = Si, Ge, Sn)—[4+3]-Coordination at Si, Ge vs. Heptacoordination at Sn

by Sarah Kuß, Erica Brendler and Jörg Wagler

Crystals 2022, 12(12), 1802; https://doi.org/10.3390/cryst12121802 - 10 Dec 2022

Cited by 4 | Viewed by 1686

Abstract

The phenyltetrel pyridine-2-olates PhE(pyO)₃ (E = Si, Ge, Sn; pyO = pyridine-2-olate) were synthesized from the respective chlorides PhECl₃ and 2-hydroxypyridine (2-pyridone) with the aid of a sacrificial base (triethylamine). Their solid-state structures were determined by [...] Read more.

The phenyltetrel pyridine-2-olates PhE(pyO)₃ (E = Si, Ge, Sn; pyO = pyridine-2-olate) were synthesized from the respective chlorides PhECl₃ and 2-hydroxypyridine (2-pyridone) with the aid of a sacrificial base (triethylamine). Their solid-state structures were determined by single-crystal X-ray diffraction. PhSi(pyO)₃ exhibits a three-fold capped tetrahedral Si coordination sphere ([4+3]-coordination, Si···N separations ca. 3.0 Å), in accordance with structures of previously reported silicon pyridine-2-olates. PhGe(pyO)₃ adopts a related [4+3]-coordination mode, which differs in terms of the tetrahedral faces capped by the pyridine N atoms. Additionally, shorter Ge···N separations (2.8–2.9 Å) indicate a trend toward tetrel hypercoordination. PhSn(pyO)₃ features heptacoordinate tin within a pentagonal bipyramidal Sn coordination sphere (Sn···N separations 2.2–2.4 Å). For the Si and Sn compounds, ²⁹Si and ¹¹⁹Sn NMR spectroscopy indicates retention of their tetrel coordination number in chloroform solution. Full article

(This article belongs to the Special Issue The Polyhedral Face of Coordination Chemistry)

► Show Figures

Figure 1

Journal Menu

Journal Browser

The Polyhedral Face of Coordination Chemistry

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (10 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI