Organometallic compounds of the lanthanides - Part CIXXX. Synthesis, structure and hydrolysis of 'moderately stable' hydrosilylation catalysts [(eta(5)-C5H4SiMe3)(2)Ln(mu-Me)](2) and [(eta(5)-(C5H4SiMe2Bu)-Bu-t)(2)Ln(mu-Me)](2)

The lanthanidocene chloride complexes [(eta(5)-C5H4SiMe2R)(2)Ln(mu-Cl)](2) (R = Bu-t, Ln = Y (1a), Sm (1b), Lu (1c); R = Me, Ln = Y (2a), Sm (2b), Lu (2c)) are prepared from the trichlorides of yttrium, samarium or lutetium a nd tert-butyldimethylsilylcyclopentadienylpotassium or trimethylsilylcyclop entadienylpotassium, respectively. Compounds 1 and 2 react with two equival ents of methyllithium in diethyl ether to give the new dimers [(eta(5)-C5H4 SiMe2R)(2)Ln(mu-Me)](2) (R = Bu-t, Ln = Y (3a), Sm (3b), Lu (3c), R = Me, L n = Y (4a), Sm (4b), Lu (4c)) which are 'moderately stable' in atmospheric moisture. The reactions of 2 with methyllithium in a 1:4 molar ratio in THF yield the monomeric lanthanidocene methyl complexes (eta(5)-C5H4SiMe3)(2)L n(mu-Me)(2)Li(THF)(2) (Ln = Y (5a), Sm (5b), Lu (5c)). Treatment of 3 and 4 with stoichiometric amounts of H2O in toluene yields the dimeric lanthanid ocene hydroxide complexes [(eta(5)-C5H4SiMe2R)(2)Ln(mu-OH)](2) (R = Bu-t, L n = Y (6a), Sm (6b), Lu (6c); R = Me, Ln = Y (7a), Sm (7b), Lu (7c)). The m olecular structures of Ic, 4a, and 7c were determined by single crystal X-r ay diffraction. The lanthanidocene methyl complexes 3 and 4 are effective p recatalysts for hydrosilylation of alkenes and alkynes. (C) 1999 Elsevier S cience S.A. All rights reserved.