Synthesis, spectroscopy, electrochemistry, and methylation reaction of the dithiolate-based cobalt(II) complex derived from tert-butyl N-(2-mercaptoethyl)carbamate

Abstract

A dithiolate-containing a carbamate mononuclear cobalt(II) complex namely, [Co(Boc-S) 2 ] ( 1 ), was obtained by the reaction of a methanolic solution of cobalt(II) nitrate hexahydrate with two equimolar amounts of the deprotonated form of tert -butyl N -(2-mercaptoethyl)carbamate (Boc-SH). The cobalt(II) complex ( 1 ) was characterized in the solid state and in solution by using FT–IR, Raman, UV–visible, and EI–mass spectroscopies, as well as thermal and X-ray diffraction studies. Spectral data showed that the carbamate (Boc-SH) acts as a mono-anionic bidentate ligand coordinating the cobalt(II) ion through two imine nitrogen and two deprotonated thiolate sulfur donor atoms in a distorted tetrahedral geometry. The thermoanalytical data evidence that the complex is stable up to 165 °C and undergoes complete decomposition, resulting in CoO. TEM imaging of the oxide residue shows its nano size clusters, suggesting that the complex ( 1 ) may be used as a precursor for nano-oxides. X-ray powder diffraction patterns evidence an isomorphism among the complex. The redox behavior of the cobalt(II) complex was also investigated by cyclic voltammetry. The reaction of the dithiolate cobalt(II) complex ( 1 ) with methyl iodide appears to occur intramolecularly with the cobalt-bound dithiolate, forming the cobalt(II)-bound dithioether complex [Co(Boc–SCH 3 ) 2 ]I 2 ( 2 ), as a dication complex with a clean second-order reaction of 13.24 × 10 −2 M −1 ·s −1 .