Reactivity of [Os3H(CO)10(MeCN){Si(OR)3}](R = Me or Et) towards diphosphines. X-Ray crystal structures of [Os3H(CO)10{Si(OEt)3}(dppe)], [{Os3H(CO)10[Si(OMe)3]}2(µ-dppe)] and [Os3(CO)10(dppe)](dppe = Ph2PCH2CH2PPh2)

Abstract

The reactivity of [Os₃H(CO)₁₀(MeCN){Si(OR)₃}](R = Me or Et) towards diphosphines has been studied. The compounds [Os₃H(CO)₁₀{Si(OR)₃}(dppm)] are formed in high yield from the reaction with bis(diphenylphosphino)methane (dppm). Formation of three different products [Os₃H(CO)₁₀{Si(OR)₃}(dppe-P)], [{Os₃H(CO)₁₀[Si(OR)₃]}₂(µ-dppe)], and [Os₃(CO)₁₀(dppe-PP′)], has been observed from the reaction with 1,2-bis(diphenylphosphino)ethane (dppe). The product distribution is strictly dependent on the reaction stoicheiometry. The structure of [Os₃H(CO)₁₀-{Si(OEt)₃}(dppe-P)] has been determined by X-ray diffraction [monoclinic, space group P2₁/c, a= 18.092(4), b= 11.924(1), c= 23.210(5)Å, β= 108.29(2)°, Z= 4] unambiguously establishing monodentate co-ordination of the dppe ligand. The dimeric nature of [{Os₃H(CO)₁₀[Si(OMe)₃]}₂(µ-dppe)] has been crystallographically determined [monoclinic, space group C2/c, a= 18.07(2), b= 14.134(3), c= 26.60(1)Å, β= 111.72(5)°, Z= 8]. An X-ray crystallographic characterization of [Os₃(CO)₁₀(dppe-PP′)] shows the chelating mode of the dppe ligand [monoclinic, space group P2₁/c, a= 15.527(2), b= 10.405(5), c= 22.519(3)Å, β= 94.01 (1)°, Z= 4]. The compounds [{Os₃H(CO)₁₀[Si(OR)₃]}₂(µ-dppe)] can be prepared alternatively from [{Os₃(CO)₁₀(MeCN)}₂(µ-dppe)] and the appropriate silane SiH(OR)₃(R = Me or Et).