Normal and inverse primary kinetic deuterium isotope effects for C-H bond reductive elimination and oxidative addition reactions of molybdenocene and tungstenocene complexes: Evidence for benzene sigma-complex intermediates

A series of kinetic and thermodynamic deuterium isotope effects pertaining to the reactions of ansa-molybdenocene and -tungstenocene complexes of the type [Me2Si(C5Me4)(sub 2)]MRH (M = Mo, R=Ph, M = W, R = Me, Ph) is reported. It is demonstrated that the KIEs are highly dependent on the nature of the metal indicating that the energy surface for the reductive elimination of RH varies significantly for two otherwise similar systems.