AbstractThe transmetalation is a key elementary step in cross‐coupling reactions. Yet, the precise nature of its mechanism and transition state geometry are frequently elusive. This report discloses our study of the transmetalation of [PdII]‐F complexes with the silane‐ and stannane‐based trifluoromethylation agents, R3SiCF3 and R3SnCF3. A divergent reactivity was uncovered, with the stannane showing selective R‐group transfer, and the silane selective CF3‐group transfer. Using a combined experimental and computational approach, we uncovered a hitherto unrecognized transmetalation mechanism with the widely employed R3SiCF3 reagent, explaining its unique activity in metal‐catalyzed trifluoromethylations. While the stannane reacts via a cyclic, 4‐membered transition state, the silane undergoes a fundamentally different pathway and releases a difluorocarbene in the transmetalation event. Molecular dynamics studies clearly reinforced the liberation of a free CF2 carbene, which reacts with [PdII]‐F to ultimately generate [PdII]‐CF3.

中文翻译：

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PdII 三氟甲基化中锡烷和硅烷的不同反应性：循环过渡态与二氟卡宾释放

摘要金属转移是交叉偶联反应中的关键基本步骤。然而，其机制和过渡态几何结构的精确性质常常难以捉摸。该报告披露了我们对[Pd二]-F 与基于硅烷和锡烷的三氟甲基化试剂 R 的配合物3碳化硅3和R3锡CF3。发现了不同的反应性，锡烷表现出选择性 R 基团转移，而硅烷选择性 CF3‐团体转移。使用实验和计算相结合的方法，我们发现了一种迄今为止未被认识的金属转移机制，其中广泛使用的 R3碳化硅3试剂，解释了其在金属催化三氟甲基化中的独特活性。虽然锡烷通过环状四元过渡态进行反应，但硅烷经历了根本不同的途径，并在金属交换事件中释放二氟卡宾。分子动力学研究明显强化了游离 CF 的释放2卡宾，与[Pd二]‐F 最终生成[Pd二]-CF3.