Synthesis and crystal structure characterization of iron(II), cobalt(II) and nickel(II) complexes with 1,3-bis(2-pyridylmethylthio)propane

Abstract

Three new mononuclear complexes of nitrogen–sulfur donor sets, formulated as [Fe II(L)Cl 2] ( 1), [Co II(L)Cl 2] ( 2) and [Ni II(L)Cl 2] ( 3) where L = 1,3-bis(2-pyridylmethylthio)propane, were synthesized and isolated in their pure form. All the complexes were characterized by physicochemical and spectroscopic methods. The solid state structures of complexes 1 and 3 have been established by single crystal X-ray crystallography. The structural analysis evidences isomorphous crystals with the metal ion in a distorted octahedral geometry that comprises NSSN ligand donors with trans located pyridine rings and chlorides in cis positions. In dimethylformamide solution, the complexes were found to exhibit Fe II/Fe III, Co II/Co III and Ni II/Ni III quasi-reversible redox couples in cyclic voltammograms with E 1/2 values (versus Ag/AgCl at 298 K) of +0.295, +0.795 and +0.745 V for 1, 2 and 3, respectively.