Transition metal silyl complexes part 54 1. Hydrido disilanyl complexes LnM(H)SiR2SiR2H (LnM = MeCp(CO)2Mn, Cp(CO)2Re, (CO)3(PPh3)Fe)

Article abstract of DOI:10.1016/s0020-1693(96)05590-9

Hydrido disilanyl complexes of the type L_nM(H)SiPh₂SiPh₂H are obtained from HPh₂Si-SiPh₂H by photochemical reaction with MeCp(CO)₃ or by ligand exchange reactions starting from MeCpMn(CO)₂(THF), Cp(CO)₂Re(THF) or (CO)₃(PPh₃)Fe(H)SiMe₃. The dinuclear complex [MeCp(CO)₂Mn(H)SiPh₂]₂ is additionally obtained in the photochemical reaction of a 2:1 mixture of MeCpMn(CO)₃ and HSiPh₂SiPh₂H. When HMePhSi-SiMePhH or HMe₂Si-SiMe₂H is used instead of HPh₂Si-SiPh₂H, the kind of products depends on the metal fragment. Both types of complexes are formed when HMePhSi-SiMePhH is reacted with MeCpMn(CO)₂(THF), but only the mononuclear complex is obtained from CpRe(CO)₂(THF) or from (CO)₃(PPh₃)Fe(H)SiMe₃. Photochemical reaction of HMe₂Si-SiMe₂H with MeCpMn(CO)₃ yields only the dinuclear complex. The outcome of the reaction of Cp(CO)₂Re(THF) with HMe₂Si-SiMe₂H depends on the reaction temperature. At 25°C only cis-Cp(CO)₂Re(H)SiMe₂SiMe₂H was spectroscopically observed in low concentration. In refluxing THF, cis-and trans-Cp(CO)₂Re(H)SiMe₂SiMe₂H, and [Cp(CO)₂Re(H)SiMe₂]₂ are formed. Reaction of (CO)₃(PPh₃)Fe(H)SiMe₃ with HMe₂Si-SiMe₂H gives both (CO)₃(Ph₃P)Fe(H)SiMeSiMe₂H and [(CO)₃(Ph₃P)Fe(H)SiMe₂]₂. Photochemical reaction of Fe(CO)₄PPh₃ with HMe₂Si-SiMe₂H results in the formation of (CO)₂(PPh₃)₂Fe(H)₂. The hydride-bridged complex [Cp(CO₂)Re]₂(μ-H)₂ is formed as a by-product in the reactions of disilanes with CpRe(CO)₂(THF). Thermal or photochemical decomposition of the complexes L_nM(H)SiPh₂SiPh₂H preferrentially proceeds by reductive elimination of the disilane. Only in the decomposition of MeCp(CO)₂-Mn(H)SiPh₂SiPh₂H some H₂ is observed, which may be due to a 1,2-H₂ elimination.