The Zirconocene Dihydride−Alane Adducts [(Cp‘)2ZrH(μ-H)2]3Al and [(Cp‘)2ZrH(μ-H)2]2AlH (Cp‘ = Me3SiC5H4)

The reaction of (Me3SiC5H4)2ZrCl2 with excess LiAlH4 affords the product 5. The structural characterization of 5 reveals two types of aggregation of the (Me3SiC5H4)2ZrH2 and AlH3 fragments formulated as [(Me3SiC5H4)2ZrH(μ-H)2]3Al and [(Me3SiC5H4)2ZrH(μ-H)2]2AlH. In this Zr3Al aggregate, three zirconocene units form two hydrogen-atom bridges, each to a central aluminum atom, generating a pseudo-octahedral environment about the aluminum center. In each of the Zr2Al aggregates, two zirconocene fragments are bridged to a central aluminum center by two hydride atoms, yielding a distorted square-based pyramid geometry about Al. These results are presented and the implications considered.