Transition metal silyl complexes Part 54. Hydrido disilanyl complexes L nM(H)SiR 2SiR 2H (L nM = McCp(CO) 2Mn, Cp(CO) 2Re, (CO) 3(PPh 3)Fe)

Abstract

Hydrido disilanyl complexes of the type L n M(H)SiPh 2SiPh 2H are obtained from HPh 2Si-SiPh 2H 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(PPh 3)Fe(H)SiMe 3. The dinuclear complex [MeCp(CO) 2Mn(H)SiPh 2] 2 is additionally obtained in the photochemical reaction of a 2:1 mixture of McCpMn(CO) 3 and HSiPh 2SiPh 2H. When HMePhSi-SiMePhH or HMe 2Si-SiMe 2H is used instead of HPh 2Si-SiPh 2H, the kind of products depends on the metal fragment. Both types of complexes are formed when HMePhSi-SiMePhH is reacted with McCpMn(CO) 2(THF), but only the mononuclear complex is obtained from CpRe(CO) 2(THF) or from (CO) 3(PPh 3)Fe(H)SiMe 3. Photochemical reaction of HMe 2Si-SiMc 2H with McCpMn(CO) 3 yields only the dinuclear complex. The outcome of the reaction of Cp(CO) 2Re(THF) with HMe 2Si-SiMe 2H depends on the reaction temperature. At 25°C only cis-Cp(CO) 2Re(H)SiMe 2S]Me 2H was spectroscopically observed in low concentration. In refluxing THF, cis- and trans-Cp(CO) 2Re(H)SiMe 2SiMe 2H, and [Cp(CO) 2Re(H)SiMe 2] 2 are formed. Reaction of (CO) 3(PPh 3)Fe(H)SiMe 3 with HMe 2Si-SiMe 2H gives both (CO) 3(Ph 3P)Fe(H)SiMeSiMe 2H and [(CO) 3(Ph 3P)Fe(H)SiMe 2] 2. Photochemical reaction of Fe(CO) 4Pph 3 with HMe 2Si-SiMe 2H results in the formation of (CO) 2(PPh 3) 2Fe(H) 2. The hydride-bridged complex [Cp(CO 2)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 n M(H)SiPh 2SiPh 2H preferrentially proceeds by reductive elimination of the disilane. Only in the decomposition of MeCp(CO) 2Mn(H)SiPh 2SiPh 2H some H 2 is observed, which may be due to a 1,2-H 2 elimination.