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.

本研究合成了一系列以N(1)位连有二苯基吡咯烷基、C(5)位连有芳基的新型咪唑并吡啶-3-亚基配体（imidazopyridin-3-ylidene ligands）的铜(I)、银(I)及金(I)配合物，并通过X射线衍射分析（X-ray diffraction analysis）测定了其晶体结构。结构研究表明，这类大体积杂双环卡宾可对金属中心提供极强的空间位阻保护，而环外sp³杂化氮原子的反转现象则赋予配合物显著的结构柔性。