Twisting the arm: Structural Constraints in Bicyclic Expanded-Ring N-Heterocyclic Carbenes - data

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)2]X complexes. The substituted diaryl 7-NHCs are the most sterically encumbered with large buried volume (%VB) values of 40-50% with the less flexible six-membered analogues having %VB 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 %VB 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. The data presented are text files containing details of the single-crystal X-ray diffraction collection and solution. They contain fractional coordinate data based on cartesian axes that can be read by specialist software (Ortep, Mercury etc) to generate views of the molecular structures.

一系列二芳基、单芳基/烷基以及二烷基单环和双环扩环氮杂环卡宾（expanded-ring N-heterocyclic carbenes, ER-NHCs）已成功制备，并通过对15个Au(NHC)X及/或[Au(NHC)₂]X配合物的结构分析，研究了其与Au(I)的配位行为。取代二芳基7-NHCs的空间位阻最大，其埋藏体积（%VB）介于40%~50%之间，而柔性更低的六元环类似物的%VB值至少低5%。尽管包含稠合六元环与七元环的双环体系（6,7-NHCs）受限于较为尖锐的NCN键角，但它们是本文报道的二烷基衍生物中%VB值最大的一类，这一特征与杂环的固定构象以及预设甲基取代基的压缩效应密切相关。本数据集以文本文件形式呈现，包含单晶X射线衍射的数据收集与解析细节，其中包含基于笛卡尔坐标系的分数坐标数据，可通过Ortep、Mercury等专业软件读取并生成分子结构的可视化视图。