Thermal activation of hydrocarbon C-H bonds by Cp*M(NO) complexes of molybdenum and tungsten.

Gentle thermolysis of appropriate CpM(NO)(hydrocarbyl)(2) complexes (Cp = eta(5)-C(5)Me(5)) of molybdenum and tungsten results in loss of hydrocarbon and the transient formation of 16-electron CpM(NO)-containing complexes such as CpM(NO)(alkylidene), CpM(NO)(eta(2)-benzyne), CpM(NO)(eta(2)-acetylene), and CpM(NO)(eta(2)-allene) (M = Mo, W). These intermediates effect the single, double, or triple activation of hydrocarbon C-H bonds intermolecularly, the first step of these activations being the reverse of the transformations by which they were generated. This Account summarizes the various types of C-H activations that have been effected with these nitrosyl complexes and also describes the results of kinetic, mechanistic, and theoretical investigations of these processes.