retention of the metal configuration. The measured competition ratios showed that the inversion of the intermediates was slow compared to quenching with nucleophiles, indicating a high pyramidal stability of the 16-electron fragments (RRu,RC)- and (SRu,RC)-[CpRu(P−P′)]+ toward inversion in agreement with a basilica-type energy profile. Stereochemically this implies that substitution reactions in (RRu
金属手性非对映异构体(R Ru,R C)-和(S Ru,R C)-[CpRu(P-P')Hal](P-P'=(R)-Prophos和(R,R合成,分离并通过X射线晶体学表征)-Norphos,Hal = Cl,Br和I)。根据一级反应,在9:1和1:1的
氯仿/
甲醇混合物中研究卤化物交换和差向异构反应,反应温度为室温或稍高于室温。Hal交换反应中的决定速率的步骤是Ru-Hal键的解离,形成
金字塔状的16电子中间体(R Ru,R C)和(S Ru,R C)-[CpRu(P-P')] +,它们保持
金属构型。这些中间体可以反转其
金属构型或与亲核试剂反应而保留
金属构型。测量的竞争比表明,与用亲核试剂淬灭相比,中间体的转化较慢,表明16电子片段(R Ru,R C)-和(S Ru,R C)-[CpRu( P-P')] +朝着与大教堂型能量曲线一致的方向转变。从立体
化学上讲,这意味着在(R Ru,R C)-和(S