Cationic Charge-Appended Abnormal Carbenes: Synthesis and Study of Electronically Modified Abnormal N-Heterocyclic Carbenes.

A range of palladium complexes featuring electronically modified, imidazole-based abnormal N-heterocyclic carbene (aNHC) ligands have been prepared in the hopes of accessing a new class of cationic aNHC ligands electronically distinct from normal NHCs and aNHCs. These palladium complexes represent the first examples of transition metal-ligated aNHC complexes featuring a cationic moiety adjacent to the abnormal carbene center. It was anticipated that these design principles could facilitate electron transfer between the imidazolinylidene and the cationic heterocycle, thus reducing the electron density at the abnormal carbene center.

Chelated bis(NHC) complexes of saturated (imidazolin-2-ylidene) NHC ligands: structural authentication and facile ligand fragmentation.

The CH-linked bis(NHC) complexes [{(MesIm)CH}PdBr] and [{(MesIm)CH}Pd(NCMe)][PF] are reported. These represent the first structurally characterized chelated, saturated bis(NHC) complexes. The complexes are subject to facile ligand fragmentation during their synthesis.