Intermolecular C−H Bond Activation Promoted by a Titanium Alkylidyne

The transient titanium alkylidyne complex (PNP)Ti⋮CtBu (PNP = N-[2-P(CHMe2)2-4-methylphenyl]2-), prepared from α-hydrogen abstraction of the corresponding alkylidene−alkyl species (PNP)TiCHtBu(CH2tBu), can readily undergo intermolecular 1,2-addition of C−H bonds of benzene and SiMe4. Synthesis and reactivity, isotopic labeling, kinetics, and theoretical studies strongly favor an alkylidyne pathway and the α-H abstraction step to be the rate-determining step.