Structural and spectroscopic comparison of five-coordinate cobalt(II) and nickel(II) thiolato complexes with the related four-coordinate complexes

New five-coordinate cobalt(II) and nickel(II) complexes with tripodal ligand and nitrogen containing 2-mercapto-1-methylimidazole have been characterized by X-ray crystallography and spectroscopic techniques. Compared with the four-coordinate complexes, the five-coordinate complex has a dominant S σ interaction with metal(II) center as observed in copper(II) complexes.