MULTIPLE DESILYLATION OF SILYLATED CYCLOPENTADIENES PROMOTED BY IONICRUTHENIUM AND RHODIUM HALIDES

The reactivity of hydrated ruthenium trichloride and hydrated rhodium trichloride toward silylated cyclopentadienes was investigated. Treatm ent of ruthenium trichloride with (trimethylsilyl)cyclopentadiene, bis (trimethylsilyl)cyclopentadiene, or tris(trimethylsilyl)cyclopentadien e in alcohol solvents afforded ruthenocene in 85-96% isolated yields. GLC analysis of these reactions, as well as the reactions of benzyltri ethylammonium chloride with (trimethylsilyl)cyclopentadiene, bis(trime thylsilyl)cyclopentadiene, and tris(trimethylsilyl)cyclopentadiene, re vealed a novel chloride ion-induced desilylation of the silylated cycl opentadienes. These experiments demonstrated that the silylated cyclop entadienes were completely desilylated by chloride ion to afford cyclo pentadiene, which then reacted with the ruthenium ion to afford ruthen ocene. Treatment of hydrated rhodium trichloride with (trimethylsilyl) cyclopentadiene or cyclopentadiene monomer afforded cyclopentadienylrh odium dichloride oligomer in 93% and 82% yields, respectively. Treatme nt of hydrated rhodium trichloride with bis(trimethylsilyl)cyclopentad iene afforded cyclopentadienylrhodium dichloride oligomer (27%) and (t rimethylsilyl)cyclopentadienylrhodium dichloride dimer (70%). The stru cture of (trimethylsilyl)cyclopentadienylrhodium dichloride dimer was determined, showing that this compound crystallized in the triclinic s pace group P1BAR with cell dimensions a = 10.797(6) angstrom, b = 11.2 04(4) angstrom, c = 11.335(3) angstrom, alpha = 79.23(2)-degrees, beta = 70.28(3)-degrees, gamma = 64.75(3)-degrees, V = 1166.0(8) angstrom3 , and Z = 2.