Reactions of a hydrido(hydrosilylene) tungsten complex with oxiranes

Reactivity of a hydrido(hydrosilylene)tungsten complex, Cp*(CO)(2)(H)W=Si(H)[C(SiMe3)(3)] (1), toward oxiranes was investigated. Treatment of I with racemic mono-substituted oxiranes with a substituent R (R = Ph, vinyl, Bu-t, or Bu-n) at room temperature produced dihydrido(vinyloxysilyl)tungsten complexes, (E)- and/or (Z)-Cp*(CO)(2)(H)(2)W {Si(H)(OCH=CHR)[C(SiMe3)(3)]} [(E/Z)-2: R = Ph, (E)-3: R = vinyl, (E)-4: R = Bu-t, (E/Z)-5: R = Bu-n] in high yields via regioselective ring-opening of oxiranes. When the substituent R on oxirane was relatively large, (E)-isomers (2, 3, and 4) were obtained predominantly (87-97%), while the substituent was a relatively small Bu-n group, an approximately 1:1 mixture of (E)- and (Z)-isomers [(E/Z)-5] was obtained. Reaction of 1 with 2,2-dimethyloxirane afforded the corresponding complex, Cp*(CO)(2)(H)(2)W{Si(H)(OCH=CMe2)[C(SiMe3)(3)]} (6), quantitatively. A reaction mechanism is also discussed. (c) 2006 Elsevier B.V. All rights reserved.