Abstract
Reduction of [ZrCl2{η5-C5Me4(SiMe3)}2] (1) with excess magnesium in tetrahydrofuran affords a mixture of monomeric zirconocene hydride [ZrH{η1:η5-C5Me4(SiMe2CH2)}{η5-C5Me4(SiMe3)}] (2) and dimeric, tetranuclear Zr(III)- and Zr(IV)-magnesium hydride complexes 3 and 4, respectively. In the presence of bis(trimethylsilyl)ethyne (btmse), a similar reduction yields the η2-alkyne complex [Zr{η5-C5Me4(SiMe3)}2(η2-btmse)] (5) as the major product and compounds 2-4 as minor impurities.
Upon thermolysis in vacuum, 5 undergoes a two-fold hydrogen transfer from trimethylsilyl groups in the zirconocene intermediate to leaving btmse to afford [Zr{η5:η1-C5Me4(SiMe2CH2)}2] (6) and a mixture of alkenes (E)- and (Z)-Me3SiCH=CHSiMe3 (E >> Z). Crystal structures of compounds 2, 4, 5, and 6 were determined by X-ray crystallography.