Reaction Chemistry of Zirconocene(II) with Ferrocenyl Carbonyls§

Abstract

Treatment of {Zr}(η²-Me₃SiC≡CSiMe₃)(py) ({Zr}=Zr(η⁵-C₅H₅)₂; py=C₅H₅N) (1) with FcC(O)H (Fc=Fe(η⁵-C₅H₅)(η⁵-C₅H₄)) (2 a) gives dimeric [{Zr}(η²-OCHFc)]₂ (3), while the reaction of 1 with ketone FcC(O)Ph (2 b) produces monomeric metallaoxiran [{Zr}(η²-OCPhFc)(Ph)] (4). In contrast, compound 1 forms [{Zr}(O=CFc₂)₂] (5) in presence of FcC(O)Fc (2 c). The structures of 3–5 in the solid state were determined by single crystal X-ray analysis. In 3 two {Zr}(η²-OCHFc) building blocks are connected to each other over oxygen bridges with the aldehydes being η²-coordinated. By exchanging aldehyde 2 a by ketone 2 b, monomeric 4 is accessible with a σ-bonded phenylate ligand and a ketone bonded in a η²-fashion to Zr(IV). In contrast, within 5 two Fc₂C=O ketones are datively bonded to a zirconocene unit with Zr in the oxidation state II, demonstrating a new family of compounds in which metallocene ketones are coordinated to a group 4 metal. Further, compounds 3–5 were characterized by IR spectroscopy and 3, 4 were investigated by matrix assisted laser desorption/ionization mass spectrometry. In case of 5, its crystallisation was tracked by NMR spectroscopy and its reaction towards CH₂Cl₂ was investigated by high resolution mass spectrometry.