Hydrolysis and Transfer Reactivity of the Coordinated Thiolate, Thiocarboxylate, and Selenolate in Binuclear Zinc(II) Complexes.

A new binuclear Zn(II) complex, [Zn(PhBIMP)(DMF)] () (where PhBIMP is the anion of 2,6-bis[bis[(-methyl-4,5-diphenylimidazoylmethyl)amino]methyl]-4-methylphenol), has been shown for the first time to mediate the hydrolytic C-S bond cleavage of a series of aliphatic and aromatic thiolates to yield the corresponding alcohols/phenols along with the formation of a hydrosulfide-bridged complex, [Zn(PhBIMP)(μ-SH)(DMF)] (), which has been thoroughly characterized in comparison with the corresponding chloride complex, [Zn(PhBIMP)(Cl)(DMF)] (), as a control. The binuclear Zn(II)-thiolate complexes [Zn(PhBIMP)(μ-SR)] (R = Ph, ; 3-Br-CH, ) have also been synthesized by avoiding the C-S bond cleavage reaction. Based on the experimental results for the effects of HO and EtN on , , and , the complex [Zn(PhBIMP)(μ-SR)(OH)] has been proposed to be the active intermediate that precedes the C-S bond cleavage of thiolates. The complex [Zn(PhBIMP)(μ-SCOPh)(DMF)] () also demonstrates the hydrolysis of the coordinated thiobenzoate to produce [Zn(PhBIMP)(μ-OCPh)(MeCN)] (). However, unlike and , the benzeneselenolate-bridged complex, [Zn(PhBIMP)(μ-SePh)] (), does not generate the species, [Zn(PhBIMP)(μ-SePh)(OH)], in solution, and in line with that, the coordinated benzeneselenolate in does not undergo hydrolysis to generate hydroselenide and phenol. Finally, a comparative study for the transfer reactivity of the bridging -SH, -SPh, -SC(O)Ph, and -SePh ligands in , , , and , respectively, toward selected organic substrates has been performed to reveal the distinct differences in the reactivity of these bridging ligands.