IU CINQUIMA/Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, Valladolid 47071, Spain.
Chem Commun (Camb). 2023 Feb 14;59(14):1975-1978. doi: 10.1039/d2cc06415d.
F NMR monitoring shows that heating -[AuRfI] solutions (Rf = CFCl-3,5) leads to formation of -[AuRfI], [AuRfI] and [AuRfI] kinetic competition between isomerization and Rf/I scrambling. The system evolution is driven by the easy Rf-I reductive elimination from [AuRfI] (forming also [AuI]), which is faster than any of the Rf-Rf couplings from the coexisting species, hindering the commonly desired and thermodynamically preferred C-C coupling. A kinetic model where I dissociation triggers both isomerization and transmetalation steps is proposed, which fits well the experimental data. DFT calculations support that the lower bond strength of Au-I compared to other halides produces a pathway switch that makes C-I coupling kinetically preferred. Consequently, it is better avoided in reactions looking for C-C coupling.
F NMR 监测表明，加热 -[AuRfI]溶液（Rf = CFCl-3,5）会导致 -[AuRfI]、[AuRfI]和[AuRfI]的形成，以及异构体异构化和 Rf/I 重排之间的动力学竞争。该体系的演化是由[AuRfI]中 Rf-I 的还原消除驱动的（也形成[AuI]），这比共存物种中任何 Rf-Rf 偶联都快，阻碍了通常期望的和热力学上有利的 C-C 偶联。提出了一个动力学模型，其中 I 解离触发异构化和转金属化步骤，该模型很好地拟合了实验数据。DFT 计算支持 Au-I 与其他卤化物相比较低的键强度产生了一个途径切换，使得 C-I 偶联在动力学上更有利。因此，在寻找 C-C 偶联的反应中最好避免这种偶联。
