Unlike an unruly brolly or the striking lily of the Nile, the celebrated umbrella-like S_N2 inversion has not been directly observed until now. In their Communication on page 1480 ff., K. Nikitin, D. G. Gilheany, et al. demonstrate direct observation of inversion in a low-temperature NMR-EXSY experiment using an inseparable mixture of isomers. Fast nucleophilic attack of a halide ion on a phosphonium center has all the characteristics of an associative process and leads to inversion of the P configuration.

中文翻译：

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封底内页：卤化Spec物种中的动态交叉交换：SN2过程中立体化学转化的直接观察（Angew。Chem。Int。Ed。6/2018）

不同于 尼罗河上的杂草丛生或引人注目的百合花，迄今尚未直接观察到著名的伞状S _N 2倒置。K. Nikitin，D.G。Gilheany等在其第1480页及其后的通讯中。在低温NMR-EXSY实验中，使用不可分离的异构体混合物，可以直接观察到反演。lide离子对center中心的快速亲核攻击具有缔合过程的所有特征，并导致P构型的反转。