Homogeneous Model Complexes for Supported Rhenia Metathesis Catalysts

A series of rhenium trioxo complexes (L–ReO3) was synthesized, characterized, and demonstrated to be active in olefin metathesis. The relationship between perrhenate (ReO4–), perrhenyl (ReO3+), and metathesis-active rhenium complexes (L–ReO3) was elucidated. Their chemical behavior can be tuned through the Lewis acid–base interaction. DFT calculations were performed for the metathesis reaction of L–ReO3 with norbornene, which demonstrates that electron-withdrawing substituents or ligands are beneficial for olefin metathesis activity. Moreover, a rhenium–alkylidene complex was synthesized, which can be activated by B­(C6F5)3 to afford an active metathesis catalyst. This system can be regarded as a homogeneous model of the hypothetical species present in the heterogeneous catalytic systems. The findings from the present study are consistent with our previous gas-phase studies and constitute the elucidation of the working principles for the metathesis-active rhenium species on the surface.