Nickel(II) tri-tert-butoxysilanethiolates with N-heterocyclic bases as additional ligands: Synthesis, molecular structure and spectral studies

Three heteroleptic, neutral nickel(II) tri-tert-butoxysilanethiolates with monodentate heterocyclic bases (pyridine, 2-methylpyridine and 3,5-dimethylpyridine) serving as additional ligands have been prepared following the same synthetic procedure. The complexes were characterized by single crystal X-ray structure determination and elemental analysis. For complexes 1 and 2, FT-IR and UV–Vis spectroscopy have been additionally recorded.Three different coordination motifs have been observed in these complexes. Molecules building tetragonal crystals of [Ni{SSi(OtBu)3}2(C5H5N)] (1) feature Ni(II) coordinated by two S,O-chelating tri-tert-butoxysilanethiolato residues and one N atom of pyridine in a strongly distorted trigonal bipyramidal environment. The complex [Ni{SSi(OtBu)3}2(C6H7N)2] (2) forms triclinic crystals and its core atoms adopt a planar geometry with Ni(II) in the middle of the N2S2 plane. Molecules of complex [Ni{SSi(OtBu)3}2(C7H9N)2(H2O)] (3) form orthorhombic crystals with penta-coordinated Ni(II) in a distorted tetragonal pyramidal NiN2OS2 environment. Complex 2 roughly mimics one of the two metal centers in the active site of the ACS/CODH enzyme.

Three neutral nickel(II) tri-tert-butoxysilanethiolates with monodentate heterocyclic bases (pyridine, 2-methylpyridine and 3,5-dimethylpyridine) have been obtained in the crystalline form and studied by X-ray crystallography and FT-IR and UV–Vis spectroscopic methods. Complexes 1–3 exhibit different ligand compositions around the metal ion and different coordination geometries: tetragonal pyramidal 1, square-planar 2 and trigonal bipyramidal 3.Figure optionsDownload as PowerPoint slideHighlights
► Three novel Ni(II) tri-tert-butoxysilanethiolates with N-heterocyclic bases obtained.
► Different geometries and coordination environments founded for the nickel(II) centers.
► Characterization by X-ray diffraction, FT-IR, UV–Vis and elemental analysis.