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

Abstract

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 1, M = Co(II) complex 2) were obtained from the respective chlorides. Zinc complexes of the general formula Zn(acac)(TDST)(L), where L = EtOH (complex 3) or H₂O (complex 4), 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.