Alkylation of a Dimolybdenum SO Bridge, Subsequent Reactions, and Characterization of the Thioperoxide Bridge

The SO bridge of the complex, [Mo2(NTo)2(S2P(OEt)2)2(μ-O2CMe)(μ-SBn)(μ-SO)], 1, displayed nucleophilicity at O, giving alkylation products [Mo2(NTo)2(S2P(OEt)2)2(μ-O2CMe)(μ-SBn)(μ-SOR)]+, 4+, which contained the thioperoxide bridge. These cations were then subject to nucleophilic attack by two pathways. Debenzylation of the bridge thiolate in 4+ afforded neutral [Mo2(NTo)2(S2P(OEt)2)2(μ-O2CMe)(μ-S)(μ-SOR)], 5; de-esterification of a dithiophosphate ligand in 4+ gave [Mo2(NTo)2(S2P(O)(OEt))(S2P(OEt)2)(μ-O2CMe)(μ-SBn)(μ-SO)], 6, which contained a monoester, dithiophosphate ligand. Complex 1 gave a slow and clean reaction in the crystalline state, further demonstrating its nucleophilicity by attacking a neighboring molecule in its lattice. X-ray crystallography confirmed the thioperoxide linkage and revealed structural similarities of the Mo2(μ-SOR) unit to sulfenate esters (RSOR) and related derivatives.