INTERACTIONS OF HAFNOCENE AND ZIRCONOCENE DIHYDRIDES WITH ACETYLENES - SYNTHESIS OF THE FIRST ACETYLENE COMPLEX OF HAFNIUM

The first acetylene complex of hafnium, CP2Hf[Me3SiC=CHf(H)CP2], Was s ynthesized by the reaction of hafnocene dihydride Cp2HfH2 with bis(tri methylsilyl)acetylene in benzene. The reaction is accompanied by elimi nation of the Me3Si group from the molecule of the initial acetylene, as a result of which the acetylenide derivative of hafnium CP2Hf(C=CSi Me3)(H) acts as an acetylene ligand in the complex. Under analogous co nditions, the reaction of zirconocene dihydride Cp2ZrH2 with bis(trime thylsilyl)acetylene affords an analogous acetylene complex of zirconiu m Cp2Zr[M3SiC=CZr(H)Cp-2]. Reactions of Cp2HfH2 with tolane and 3-hexy ne proceed differently than the reaction with bis(trimethylsilyl)acety lene. Here the corresponding hafnacyclopentadiene metallacycles are th e final products.