School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK.
School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK and Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK.
Dalton Trans. 2019 Feb 7;48(5):1850-1858. doi: 10.1039/c8dt04462g. Epub 2019 Jan 17.
A series of diaryl, mono-aryl/alkyl and dialkyl mono- and bicyclic expanded-ring N-heterocyclic carbenes (ER-NHCs) have been prepared and their complexation to Au(i) investigated through the structural analysis of fifteen Au(NHC)X and/or [Au(NHC)]X complexes. The substituted diaryl 7-NHCs are the most sterically encumbered with large buried volume (%V) values of 40-50% with the less flexible six-membered analogues having %V values at least 5% smaller. Although the bicyclic systems containing fused 6- and 7-membered rings (6,7-NHCs) are constrained with relatively acute NCN bond angles, they have the largest %V values of the dialkyl derivatives reported here, a feature related to the fixed conformation of the heterocyclic rings and the compressional effect of a pre-set methyl substituent.
已经制备了一系列二芳基、单芳基/烷基和二烷基单环和双环扩展环 N-杂环卡宾（ER-NHC），并通过对十五个 Au(NHC)X 和/或 [Au(NHC)]X 配合物的结构分析研究了它们与 Au(i)的络合作用。取代的二芳基 7-NHC 是最具空间位阻的，具有 40-50%的大埋藏体积（%V）值，而较不灵活的六元类似物的%V 值至少小 5%。尽管含有稠合的 6-和 7-元环的双环系统（6,7-NHC）具有相对锐角的 NCN 键角，但它们具有这里报道的二烷基衍生物中最大的%V 值，这一特征与杂环环的固定构象和预设甲基取代基的压缩效应有关。
