Terminal {Ni(II)-SH} complex promoted anaerobic catalytic sulfur atom transfer reaction: implication to the sulfide oxidase function of Cu/Zn-superoxide dismutase.

In mitochondria, the detoxification of molar excess H 2 S as polysulfide proceeded via an oxidation process promoted by Cu/Zn containing superoxide dismutase (SOD1) enzyme, which has been very recently reported as the alternative enzyme for cytosolic H 2 S oxidation. Herein, we present Ni(II) complexes bearing the terminal SH group as a synthetic functional analogue for the sulfide oxidase function of SOD1. Synthesis, crystal structure and complete spectroscopic characterization of two sets of complexes, [NiL OMe/ t Bu (PPh 3 )] (2OMe/tBu) and tetraethyl salt of [NiL OMe/ t Bu (SH)] -1 (3OMe/tBu), were described (LOMe = ( E )-2-methoxy-6-(((2-sulfidophenyl)imino)methyl)phenolate and LtBu = ( E )-2,4-di- tert -butyl-6-(((2-sulfidophenyl)imino)methyl)phenolate). Under anaerobic conditions, 3OMe/tBu responded to a catalytic sulfur atom transfer (SAT) reaction with PPh 3 to produce SPPh 3 . The SAT reaction was analyzed using detailed studies of 1 H and 31 P NMR spectra. Finally, the SAT reactivity pattern was compared with the same in the native enzyme of SOD1.