Tuning of Cr-Cr Magnetic Exchange through Chalcogenide Linkers in Cr2 Molecular Dimers

A set of three Cr-dimer compounds, Cr₂Q₂(en)₄X₂ (Q: S, Se; X: Br, Cl; en: ethylenediamine), with monoatomic chalcogenide bridges have been synthesized via a single-step solvothermal route. Chalcogenide linkers mediate magnetic exchange between Cr³⁺ centers, while bidentate ethylenediamine ligands complete the distorted octahedral coordination of Cr centers. Unlike the compounds previously reported, none of the chalcogenide atoms are connected to extra ligands. Magnetic susceptibility studies indicate antiferromagnetic coupling between Cr³⁺ centers, which are moderate in Cr₂Se₂(en)₄X₂ and stronger in Cr₂S₂(en)₄Cl₂. Fitting the magnetic data requires a biquadratic exchange term. High-frequency EPR spectra showing characteristic signals due to coupled S = 1 spin states could be interpreted in terms of the "giant spin" Hamiltonian. A fourth compound, Cr₂Se₈(en)₄, has a single diatomic Se bridge connecting the two Cr³⁺ centers and shows weak ferromagnetic exchange interactions. This work demonstrates the tunability in strength and type of exchange interactions between metal centers by manipulating the interatomic distances and number of bridging chalcogenide linkers.

The unusual ring scission of a quinoxaline-pyran-fused dithiolene system related to molybdopterin

The reduction of a bioinspired dithiolene system in acidic medium led to an unprecedented cleavage of the C–O bond in the pyran ring.

Coordination Programming of Two-Dimensional Metal Complex Frameworks

Since the discovery of graphene, two-dimensional materials with atomic thickness have attracted much attention because of their characteristic physical and chemical properties. Recently, coordination nanosheets (CONASHs) came into the world as new series of two-dimensional frameworks, which can show various functions based on metal complexes formed by numerous combinations of metal ions and ligands. This Feature Article provides an overview of recent progress in synthesizing CONASHs and in elucidating their intriguing electrical, sensing, and catalytic properties. We also review recent theoretical studies on the prediction of the unique electronic structures, magnetism, and catalytic ability of materials based on CONASHs. Future prospects for applying CONASHs to novel applications are also discussed.

Investigation into the reactivity of 16-electron complexes Cp#Co(S2C2B10H10) (Cp# = Cp, Cp*) towards methyl diazoacetate and toluenesulphonyl azide

A three-component reaction of the 16-electron half-sandwich complex Cp*Co(S₂C₂B₁₀H₁₀) (2) with both methyl diazoacetate (MDA) and toluenesulphonyl azide (TsN₃) led to the formation of complexes 3 and 4, while a two-component reaction of complex 2 with MDA afforded products 5–7.

Synthesis, structure and theoretical investigation into a homoleptic tris(dithiolene) tungsten

A new homoleptic dithiolene tungsten complex, tris-{1,2-bis(3,5-dimethoxyphenyl)-1,2-ethylenodithiolene-S,S'}tungsten, was successfully synthesized via a reaction of the thiophosphate ester and sodium tungstate. The thiophosphate ester was prepared from 3,5-dimethoxybenzaldehyde via benzoin condensation to produce the intermediate 1,2-bis-(3,5-dimethoxyphenyl)-2-hydroxy-ethanone compound, followed by a reaction of the intermediate with phosphorus pentasulfide. FTIR, UV-Vis spectroscopy, 1H NMR and 13C NMR and elemental analysis confirmed the product as tris{1,2-bis-(3,5-dimethoxyphenyl)-1,2-ethylenodithiolene-S,S'}tungsten with the molecular formula of C54H54O12S6W. Crystals of the product adopted a monoclinic system with space group of P2(1)/n, where a=12.756(2) Å, b=21.560(3) Å, c=24.980(4) Å and β=103.998(3)°. Three thioester ligands were attached to the tungsten as bidentate chelates to form a distorted octahedral geometry. Density functional theory calculations were performed to investigate the molecular properties in a generalized-gradient approximation framework system using Perdew-Burke-Ernzerhof functions and a double numeric plus polarization basis set. The HOMO was concentrated on the phenyl ligands, while the LUMO was found along the W(S2C2)3 rings. The theoretical optical properties showed a slight blue shift in several low dielectric solvents. The solvatochromism effect was insignificant for high polar solvents.

An organometallic dithiolene complex exhibiting electrochemically initiated hydrogen generation

We clarify the electrochemical behavior of an organometallic cobalt dithiolene complex (1-NH) with a secondary sulfonyl amide (–NHSO(2)–) substituted Cp ligand involving proton dynamics. The reductions of 1-NH and its deprotonated derivative (1-N(−)) are centered on the CpCoS(2) moiety. The 2e(−) reduction of 1-NH quantitatively gives 1-N(−) with hydrogen generation.