Reversible C-H Bond Activation Reactions of the N-Heterocyclic Carbene Ligands in Ru(Ph_2PCH_2CH_2CH_2PPh_2)(IMes)(CO)H_2 and Ru(Ph_2AsCH_2CH_2PPh_2)(IMes)(CO)H_2 (IMe=1,3-Dimesityl-1,3-dihydro-2H-imidazol-2-ylidene)

摘要

Thermolysis of Ru(IMes)(dppp)(CO)H_2 (1,IMes=1,3-dimesityl-1,3-dihydro-2H-imidazol-2-ylidene;dppp=Ph_2PCH_2CH_2CH_2PPh_2) in the presence of trimethylvinylsilane yields Ru(IMes')(dppp)(CO)H (2) resulting from intramolecular ArCH_2-H C-H bond activation of the N-heterocyclic carbene ligand.The structures of 1 and 2 have been established by X-ray crystallography.Treatment of Ru(IMes)(arphos)(CO)H_2 (3,arphos=Ph_2AsCH_2CH_2PPh_2) with CH_2=CHSiMe_3 at 85 deg C produces a mixture of three C-H activated products 4a-c.The C-H activated complexes 2 and 4a-c reform their dihydride precursors upon heating under hydrogen.