Tskhovrebov Alexander G, Lingnau Julia B, Fürstner Alois
Max-Planck-Institut für Kohlenforschung, 45470, Mülheim/Ruhr, Germany.
Angew Chem Int Ed Engl. 2019 Jun 24;58(26):8834-8838. doi: 10.1002/anie.201903957. Epub 2019 May 16.
Gold carbenes of the general type [LAu=CR ] are sufficiently long-lived for spectroscopic inspection only if the substituents compensate for the largely missing stabilization of the carbene center by the [LAu] fragment. π-Donation by two fluorine substituents (R=F) is insufficient; rather, difluorocarbene complexes are so deprived in electron density that they sequester even "weakly coordinating" anions such as triflate or triflimide. This particular bonding situation translates into unmistakable carbenium ion chemistry upon reaction with stilbene as a model substrate.
一般类型为[LAu=CR ]的金卡宾只有在取代基补偿了[LAu]片段对卡宾中心基本缺失的稳定作用时，才具有足够长的寿命用于光谱检测。两个氟取代基（R=F）的π供电子作用是不够的；相反，二氟卡宾配合物的电子密度极低，以至于它们甚至能螯合诸如三氟甲磺酸根或双（三氟甲基磺酰）亚胺等“弱配位”阴离子。与作为模型底物的芪反应时，这种特殊的键合情况转化为明确无误的碳正离子化学。
