Syntheses and structures of four- and five-coordinate bio-related zinc complexes containing dithiolate–diamine ligands

Synthesis and characterization of mononuclear Zn(II), Co(II) and Ni(II) complexes containing a sterically demanding silanethiolate ligand derived from tris(2,6-diisopropylphenoxy)silanethiol

Four heteroleptic complexes of nickel(ii), cobalt(ii) and zinc(ii), containing a monodentate silanethiolate ligand derived from tris(2,6-diisopropylphenoxy)silanethiol (TDST), were prepared and characterized. Nickel(ii) and cobalt(ii) complexes of the formula M(NH3)2(TDST)2 (M = Ni(ii) complex , M = Co(ii) complex ) were obtained from the respective chlorides. Zinc complexes of the general formula Zn(acac)(TDST)(L), where L = EtOH (complex ) or H2O (complex ), were obtained from zinc acetylacetonate. A single-crystal X-ray structural analysis revealed that all crystalline products are solvent adducts. The geometries of ligands in the complexes are typical: distorted tetrahedral in zinc and cobalt(ii) complexes and square planar in nickel(ii) compounds. Magnetic studies performed for Ni(ii) and Co(ii) compounds confirmed the diamagnetic character of the first complex and high-spin paramagnetic configuration of the latter. Nickel(ii) and cobalt(ii) complexes were additionally characterized by UV-Vis and IR spectroscopy. IR bands for ligands in the complexes were assigned with the help of the DFT vibrational frequency calculations.

Bis{μ-2,2'-[(butane-2,3-diylidene)bis(azanylylidene)]dibenzenethiolato}dizinc(II)-dimethyl sulfoxide-methanol (2/0.18/0.82)

The asymmetric unit in the crystal structure of the title compound, [Zn2(C16H14N2S2)2]2·0.18C2H6OS·0.82CH3OH, consists of two ordered bis{μ-2,2'-[(butane-2,3-diylidene)bis(azanylylidene)]dibenzenethiolato}dizinc(II) molecules and a disordered solvent combination at the same location which refined to 18.1 (7)% dimethyl sulfoxide and 81.9 (7)% methanol. The compound has a metallic cluster structure formed by the joining together of two zinc(II) complex molecules, forming a rhomboidal Zn2S2 arrangement. This complex was previously suggested on the basis of nonstructural evidence to be a monomer [Jadamus, Fernando & Freiser (1964). J. Am. Chem. Soc. 86, 3056-3059]. Each Zn(II) atom is five-coordinated and exhibits distorted trigonal bipyramidal geometry. The structure may be of interest with respect to zinc-thiolate bonds, the coordination chemistry of Schiff bases and the folding of proteins. The structure displays weak intermolecular C-H···S, C-H···O and C-H···N interactions, and contains a unique bonding arrangement of the ligands around the Zn2S2 rhomboid.