REACTIONS OF THE ZIRCONOCENE COMPLEXES OF BIS(TRIMETHYLSILYL)ACETYLENE WITH FORMALDEHYDE, BENZALDEHYDE, AND BENZOPHENONE

In reactions of the zirconocene derivative Cp(2)ZrC(SiMe(3))=C(SiMe(3) )(THF) with ketones and aldehydes the influence of the various substit uents of the carbonyl compounds upon the formation of different produc ts was investigated. Formaldehyde reacts by an insertion of the carbon yl unit into a Zr-C bond to give a metallacycle which is additionally stabilized by the formation of a coordination dimer [Cp(2)ZrOCH(2)C(Si Me(3))=C(SiMe(3))](2) (1). Benzaldehyde yields a monomeric metallacycl e Cp(2)ZrOCHPhC(SiMe(3))=C(SiMe(3)) (2). Complex 2 is less stable than 1, and at higher temperatures it loses half of its moiety Me(3)SiC(2) SiMe(3), leaving HPhC(SiMe(3)>=C(SiMe(3))][Cp(2)Zr(eta(2)-O=CHPh)]} (3 ). Benzophenone gives no insertion,and the monomeric eta(2)-ketone com plex Cp(2)Zr(THF)(eta(2)-O=CPh(2)) (4) was obtained.