Beryllium-Induced C—N Bond Activation and Ring Opening of an N-Heterocyclic Carbene

摘要

The widespread use of N-heterocyclic (imidazol-2-ylidene) carbenes (NHCs) has been driven by their ease of synthesis and their ability to act as robust two-electron σ-donor ligands. While this latter attribute has proven to be especially advantageous in homogeneous catalytic applications, a variety of NHC activation and catalyst deactivation pathways have also been identified. A number of groups have observed that N-alkyl and N-aryl-substituted NHCs are prone to both C—H and C—N activation of the peripheral organic substituents within the coordination sphere of transition-metal centers. Herein we report that the imidazol-2-ylidene ring is prone to reductive ring opening in the presence of reactive hydride compounds; observations that may be of particular relevance to hydride poisoning of NHC-based catalysts.