Synthesis and reactivity of asymmetrically substituted ansa-bridged zirconocene complexes: X-ray crystal structures of [Zr{R(H)C(η5-C5Me4)(η5-C5H4)}Cl2] (R = Bun, But) and [Zr{Bun(H)C(η5-C5Me4)(η5-C5H4)}(CH2Ph)2]

The dialkyl complexes, [Zr{R(H)C(η5-C5Me4)(η5-C5H4)}R2′] (R = Pri, R′ = Me (2a), CH2Ph (3a); R = Bun, R′ = Me (2b), CH2Ph (3b); R = But, R′ = Me (2c), CH2Ph (3c); R = Ph, R′ = Me (2d), CH2Ph (3d)), have been synthesized by the reaction of the ansa-metallocene dichloride complex, [Zr{R(H)C(η5-C5Me4)(η5-C5H4)}Cl2] (R = Pri (1a), Bun (1b), But (1c), Ph (1d)), and two molar equivalents of the alkyl Gringard reagent. The insertion reaction of the isocyanide reagent, CNC6H3Me2-2,6, into the zirconium–carbon σ-bond of 2 gave the corresponding η2-iminoacyl derivatives, [Zr{R(H)C(η5-C5Me4)(η5-C5H4)}{η2-MeCNC6H3Me2-2,6}Me] (R = Pri (4a), Bun (4b), But (4c), Ph (4d)). The molecular structures of 1b, 1c and 3b have been determined by single-crystal X-ray diffraction studies.

The synthesis and structural characterization of ansa-zirconocene complexes with asymmetric substitution at the ansa-bridging atom is described. Their reactivity in alkylation and isocyanide insertion processes has also been studied.Figure optionsDownload as PowerPoint slide