Reactions of the zirconocene complexes of bis(trimethylsilyl)acetylene with formaldehyde, benzaldehyde, and benzophenone

Article abstract of DOI:10.1021/om950664v

In reactions .of the zirconocene derivative Cp₂ZrC(SiMe₃)=C(SiMe₃)(THF) with ketones and aldehydes the influence of the various substituents of the carbonyl compounds upon the formation of different products was investigated. Formaldehyde reacts by an insertion of the carbonyl unit into a Zr-C bond to give a metallacycle which is additionally stabilized by the formation of a coordination dimer [Cp₂ZrOCH₂C(SiMe₃)=C(SiMe₃)] ₂ (1). Benzaldehyde yields a monomeric metallacycle Cp₂ZrOCHPhC(SiMe₃)=C(SiMe₃) (2). Complex 2 is less stable than 1, and at higher temperatures it loses half of its moiety Me₃SiC₂SiMe₃, leaving {[Cp₂ZrOCHPhC(SiMe₃)=C(SiMe₃)][Cp ₂Zr(η²-O=CHPh)]} (3). Benzophenone gives no insertion, and the monomeric η²-ketone complex Cp₂Zr(THF)(η²-O=CPh₂) (4) was obtained.