Alkylzirconium-(III) and alkylzirconium-(IV) complexes

Abstract

The complex [(η5-C5H5)2ZrCl]2 is oxidized by acetylenes PhCCR (R = H, Ph) to give dimeric alkenediylzirconium(IV) derivatives and can be methylated with LiMe and AlMe3. The methyl complex obtained in the reaction with LiMe is a diamagnetic solid characterized as [(η5-C5H5)ZrMe]2 by 1H NMR spectroscopy. This compound is reversibly acylated by CO, and the equilibrium can be displaced by simultaneous oxidation to give the η2-acetylzirconium(IV) complex [(η5- C5H5)2Zr(η5-COMe)]2(μ-O) The analogous insertion of CyNC (Cy = cyclohexyl) goes to completion, and the resulting diamagnetic dimer [(η5C5H5)2Zr(η2- CMeNCy)]2 has been characterized by IR and NMR spectroscopy. The methyl- zirconium(III) complex is a strong reducing agent, being oxidized by AgClO4 with deposition of metallic silver and by I2 to give (η5-C5H5 and (η5-C5H5)2ZrIMe.