Fischer aminocarbene conformers containing a 2-thienyl or 2-furyl ring: a crystallographic, NMR, and DFT study
作者:Marilé Landman、Roan Fraser、Linette Twigge、Jeanet Conradie
DOI:10.1080/00958972.2015.1046852
日期:2015.7.18
isomers. The two isomers arise from restricted rotation about the N–Ccarbene bond, that exhibits double bond character due to π-donation from nitrogen to the carbene carbon. Each isomer exists as two conformers in fast equilibrium with each other. The conformers arise from the rotation of the aryl ring around the Ccarbene–Caryl single bond with a DFT calculated rotation barrier of 0.1–0.5 eV. The main
Fischer 氨基卡宾配合物 [(CO)5M=C(NHR)Y](M=Cr 或 W;R=H、Cy 或 C2H4NH2;Y=2-噻吩基或 2-呋喃基)在溶液中以两种异构体形式存在, E 和 Z 异构体。这两种异构体源于围绕 N-Ccarbene 键的受限旋转,由于从氮到卡宾碳的 π 供体而表现出双键特征。每个异构体作为两个构象异构体存在,彼此快速平衡。构象异构体来自围绕 Ccarbene-Caryl 单键的芳环旋转,DFT 计算的旋转势垒为 0.1-0.5 eV。以固态分离的主要异构体通常显示芳环相对于氨基取代基的顺式取向和氨基取代基相对于金属的Z构型。图形概要