Dinuclear zirconium complexes containing the fulvalene ligand. Synthesis and reactivity

Reduction of Zr(η5-C5H5)(η5-1,3-tBu2C5H3)Cl2 with 1.5 equiv of 10% sodium amalgam in toluene affords the zirconium(III) derivative [Zr(η5-1,3-tBu2C5H3)(μ-Cl)]2(μ-η5-η5-C10H8) (1) which reacts with chlorine or chlorinated solvents to give the zirconium(IV) compound [Zr(η5-1,3-tBu2C5H3)Cl2]2(μ-η5-η5-C10H8) (2). When the tetrachloro fulvalene [ZrCp′Cl2]2(μ-η5-η5-C10H8) (Cp′=η5-C5H5 (Herrmann et al., Angew. Chem. Int. Ed. Engl. 26 (1987) 697); η5-1,3-tBu2C5H3 (2)) compounds were treated with four equivalents of LiR (R=Me, Ph) in toluene at −78 °C the tetraalkyl derivatives [ZrCp′R2]2(μ-η5-η5-C10H8) (Cp′=η5-C5H5, R=Me, Ph (3); η5-1,3-tBu2C5H3, R=Me (4)) were obtained. Compound 4 reacts with a stoichiometric amount of water with hydrolysis of the Zr–methyl bond to give the μ-oxo complex [Zr(η5-1,3-tBu2C5H3)(CH3)]2(μ-O)(μ-η5-η5-C10H8) (8). The zirconium alkoxide [Zr(η5-C5H5)(η2-O2SiPh2)]2(μ-η5-η5-C10H8) (5) and the iminoacyl complexes [Zr(η5-C5H5){η2-CRN(2,6-Me2C6H3)}R]2(μ-η5-η5-C10H8) (R=Me (6), Ph (7)) were prepared by reaction of the tetraalkyl complexes with either the alcohol Ph2Si(OH)2 or isocyanide CN(2,6-Me2C6H3), respectively. Two diastereoisomers of compounds 6 and 7 were obtained.