Synthesis and Reactivities of Polyhydrido Osmium Arylsilyl Complexes Prepared from OsH₃Cl(PPh₃)₃

Reactions of silanes with transition-metal complexes are of interest because their relevance to Si–H bond activation, the structural properties of polyhydrides, and catalytic hydrosilylation reactions. This work presents the results derived from reactions of arylsilanes Ph2SiH2 and PhSiH3 with OsH3Cl­(PPh3)3 (1). Reaction of 1 with 1 equiv or excess Ph2SiH2 affords OsH3(SiClPh2)­(PPh3)3 (2) or OsH4(SiClPh2)­(SiHPh2)­(PPh3)2 (3), respectively. These silyl complexes are formed via the oxidative addition of Si–H bonds and H/Cl exchange via silylene intermediates. Similarly, reaction of 1 with excess PhSiH3 produced the analogous bis­(silyl) complex OsH4(SiClHPh)­(SiH2Ph)­(PPh3)2 (4). The bis­(silyl) complexes are dodecahedral tetrahydride complexes containing weak Si···H interactions. The complex 3 reacts with PPh3 and CH3CN to selectively eliminate Ph2SiH2. Computational studies show that the preference for reductive eliminations from 3 follows the order Ph2SiH2 > H2 > Ph2SiHCl > Ph2HSi-SiClPh2.硅烷与过渡金属配合物的反应备受关注，因其与Si–H键活化、多氢化物的结构特性以及催化氢化硅烷化反应密切相关。本研究报道了芳基硅烷Ph₂SiH₂与PhSiH₃分别与OsH₃Cl(PPh₃)₃（化合物1）的反应研究结果。当化合物1与1当量或过量的Ph₂SiH₂反应时，分别得到OsH₃(SiClPh₂)(PPh₃)₃（化合物2）与OsH₄(SiClPh₂)(SiHPh₂)(PPh₃)₂（化合物3）。此类硅基配合物通过Si–H键的氧化加成以及经由硅烯中间体的氢氯交换过程生成。类似地，化合物1与过量PhSiH₃反应可得到类似的双(硅基)配合物OsH₄(SiClHPh)(SiH₂Ph)(PPh₃)₂（化合物4）。该双(硅基)配合物为具有弱Si···H相互作用的十二面体四氢化物配合物。化合物3可与PPh₃及CH₃CN（乙腈）反应，选择性脱除Ph₂SiH₂。计算化学研究表明，从化合物3发生还原消除的偏好顺序为：Ph₂SiH₂ > H₂ > Ph₂SiHCl > Ph₂HSi–SiClPh₂。