Reactivity of Rhodium-Triflate Complexes with Diphenylsilane: Evidence for Silylene Intermediacy in Stoichiometric and Catalytic Reactions
作者:Roman Goikhman、David Milstein
DOI:10.1002/chem.200400568
日期:2005.1
Addition of Ph2SiH2 to [Rh(iPr3P)2(OTf)] (1) yielded the thermally unstable RhIII adduct [Rh(iPr3P)2(OTf)(H)(SiPh2H)] (2), which decomposed to [Rh(iPr3P)2(H)2(OTf)] (3), liberating (unobserved) silylene. The silylene was trapped by 1, resulting in the RhI-silyl complex [Rh(iPr3P)2(SiPh2OTf)]. Complex 3 was converted to 2 by addition of diphenylsilane, providing a basis for a possible catalytic cycle
在[Rh(iPr3P)2(OTf)]中添加Ph2SiH2(1)得到热不稳定的RhIII加合物[Rh(iPr3P)2(OTf)(H)(SiPh2H)](2),其分解为[Rh(iPr3P) )2(H)2(OTf)](3),释放(未观察到)亚甲硅烷基。甲硅烷基被1捕获,生成RhI-甲硅烷基络合物[Rh(iPr3P)2(SiPh2OTf)]。通过加入二苯基硅烷将络合物3转化为2,为可能的催化循环提供了基础。如标记研究所示,最后的反应不涉及RhI中间体。配合物1催化了Ph2SiH2与Ph2HSi-SiHPh2的脱氢偶联。提出了在该催化循环中涉及甲硅烷基中间体的机理。在叔硅烷Ph2MeSiH和PhMe2SiH的情况下,完全缺乏催化作用以及对催化循环各个步骤的研究都为该机理提供了支持。在1存在下,Ph2SiH2与苯乙烯反应的结果取决于配合物/底物比率;在化学计量条件下,烯烃氢化胜于氢化硅烷化,而底物过量