Chiral, Sterically Demanding N‑Heterocyclic Carbenes Fused into a Heterobiaryl Skeleton: Design, Synthesis, and Structural Analysis

A series of Cu­(I), Ag­(I), and Au­(I) complexes incorporating a new family of imidazopyridin-3-ylidene ligands substituted by a diphenylpyrrolidino group at N(1) and aryl groups at C(5) has been synthesized and their structures determined by X-ray diffraction analysis. This structural study has revealed an extremely high steric protection of the metal center by the bulky heterobicyclic carbenes, while the inversion at the exocyclic N­(sp³) atom provides a remarkable flexibility