“磷桥连的三核钌羰基化合物-氮杂环卡宾”络合物中N-甲基C-H键活化机理研究

Recently the Cabeza's group reported a unique successive N-methyl C-H bond activation on a phosphine-tethered N-heterocyclic triruthenium carbene complexes. With the aid of DFT calculations, we studied the mechanism of two successive N-methyl C-H activation reaction at the molecular level. The calculated results showed that the phosphine migration occurs prior to the C?H activation. CO ligand dissociation is an essential process for the C-H bond activation. The first C-H bond activation is the rate-determining step, which needs to overcome an overall barrier of 39.0 kcal/mol. NBO analysis indicated that the electron density of the methyl group carbon atom attached to the N-heterocyclic carbene is higher than that of the ethylene carbon atom, making the C-H bond of the methyl group more easier to be activated.