Neutral Chromium Complex with a Cr≡Si Triple Bond: Synthesis and Photoinduced H-H and Benzene C-H Bond Activation

A neutral silylyne complex with a Cr equivalent to Si triple bond was prepared by dehydrogenation of a chromium silylene complex with Cr-H and Si-H bonds, and was isolated as monomeric crystals, unlike dimeric forms of its tungsten and molybdenum congeners. The strong Cr(delta-)-Si(delta+) bond polarity was revealed by the reaction with MeOH and DFT calculations. The chromium silylyne complex reacted with H2 under LED (365 nm) irradiation to reproduce the precursor silylene complex with a (H)Cr=Si(H) moiety, as a result of 1,2-H-H addition across the Cr equivalent to Si triple bond. Similarly, the chromium silylyne complex reacted with benzene under irradiation to afford an 1,2-addition product with a (H)Cr=Si(Ph) moiety, via benzene C-H bond activation accompanied by Si-C bond forming. Neutral silylyne complex with a Cr equivalent to Si bond was synthesized via dehydrogenation from a silylene complex with (H)Cr=Si(H) moiety. Its monomeric structure was revealed by XRD and DFT calculations. Irradiation of the chromium complex with H2 using LED light let to H2 activation to reproduce the (H)Cr=Si(H) complex. The chromium complex performed benzene C-H bond activation across the Cr equivalent to Si bond to afford 1,2-C-H addition product under irradiation.image