Activation of Ligand Reactivity:  Thiolate C−S and Dithiophosphate Ester C−O Heterolyses within a Dimolybdenum(V) System

Ligand reactivity was demonstrated for sulfide alkylation, thiolate dealkylation, and dithiophosphate de-esterification within molybdenum(V) dimers. The cationic complex [Mo2(NC6H4Me)2(S2P(OEt)2)2(μ-O2CMe)(μ-SR)2]+ was inductively activated toward thiolate C−S and dithiophosphate C−O heterolyses. The dealkylations were studied using anionic nucleophiles, and various reactivity patterns were characterized. The de-esterification of the diethyl dithiophosphate ligands produced complexes containing the rare monoester EtO(O)PS2 2- ligand. This ligand's phosphoryl group was poorly nucleophilic but weakly basic. Crystallographic comparisons between the activated cation and the neutral complex [Mo2(NC6H4Me)2(S2P(OEt)2)2(μ-O2CMe)(μ-S)(μ-SMe)] were conducted to delineate structural differences related to the activation. A crystallographic study was also done of the complex [Mo2(NC6H4CH3)2(S2P(OEt)2)(S2P(O)OEt)(μ-O2CMe)(μ-SEt)2], which provided internal comparison of monoester EtO(O)PS2 2- and diester (EtO)2PS2 - ligand types.