Molybdenum Chalcogenobenzimidato Complexes:  Radical Synthesis and Nitrile Extrusion via β-EPh (E = S, Se, and Te) Elimination

Molybdenum chalcogenobenzimidates of formula (Ph[PhE]CN)Mo(N[t-Bu]Ar)3 (Ar = 3,5-C6H3Me2) have been obtained by treatment of Mo(N[t-Bu]Ar)3 sequentially with benzonitrile and 0.5 equiv of PhEEPh (E = S, Se, and Te). Molecular structure determinations have been carried out for the S and Se variants. The Te variant extrudes PhCN forming structurally characterized (PhTe)Mo(N[t-Bu]Ar)3 with facility assessed via stopped-flow kinetic measurements, while the Se and S analogues exhibit increasing stability. Quantum chemical calculations and solution calorimetry have been employed as an aid to interpretation of the PhCN extrusion reaction.