Synthesis of New Silyl-Bridged Bis(cyclopentadienyl) Ligands and Complexes

Abstract

The new monobridged compound, [μ-(MePhSi)(C5H5)2] (2), was obtained as a mixture of five positional isomers from the reaction of MePhSiCl2 with 2 equiv of Li(C5H5). Deprotonation of 2 with 2 equiv of nBuLi and subsequent reaction with 1 equiv of Me2SiCl2 in THF resulted in an unsymmetrical dibridged (bis)cyclopentadienyl compound, [μ,μ-(MePhSi)(Me2Si)(C5H4)2] (3). Compound 3 was shown to be a mixture of five isomers by 1D and 2D NMR experiments. Similarly, [μ-(Me2SiCH2CH2SiMe2)(C5H5)2] (4) was deprotonated with 2 equiv of nBuLi and subsequently reacted with 1 equiv of ClMe2SiCH2CH2SiMe2Cl to provide the (bis)cyclopentadienyl compound with two four-atom bridges, [μ,μ-(Me2SiCH2CH2SiMe2)2(C5H4)2] (5). X-ray diffraction studies of sublimed 5 showed the solid state structure to be the symmetrical 1,3−1,3 trans isomer, and NMR studies of 5 indicated a mixture of isomers in solution. The 1H, 13C, 29Si, and VT NMR spectra of compounds 2, 3, and 5 are described. Deprotonation of compounds 2, 3, and 5 and subsequen...