Funktionelle trimethylphosphanderivate. XIX. Phosphinomethylsubstituierte zirconiuimverbindungen als nucleophile: Synthese, reaktion mit CO und molekülstruktur von [(C₅H₅)₂Zr(CH₂PMe₂)₂]₂Ni

The organozircomum-substituted phosphines Cp₂Zr(X)CH₂PMe₂ (Cp = η⁵-C₅H₅; X = Cl, CH₂PMe₂) have been prepared from Cp₂ZrCl₂ and LiCH₂PMe₂. In these compounds, the phosphinomethyl group acts as a monohapto (η¹-) ligand. On reaction with CO, the bis(phosphinomethyl)zirconium complex forms a red complex, which by means of NMR spectroscopy is shown to contain a novel zircona heterocycle. With Ni(COD)₂, Cp₂Zr(CH₂PMe₂)₂ forms the 2:1 complex [Cp₂Zr(CH₂PMe₂)₂]₂Ni. Crystals (from tetrahydrofuran) are triclinic, space group P1, with parameters a 13.433(5), b 18.062(3), c 19.505(2) Å, α 64.35(2), β 76.82(1), γ 71.28(2)°, V 4018.12 ų, d_x 1.445 g cm^-3 for Z = 4, μ(Mo-K_α) 11.5 cm^-1, T 21°C. Refinement of 743 parameters on 8826 reflections converged at R = 0.055. The molecular structure consists of monomeric units with two bidentate C₂Zr(CH₂PMe₂)₂ molecules acting as chelating ligands to a tetrahedral Ni⁰ centre. The six-membered Zr(CH₂PMe₂)₂Ni rings adopt a chair conformation. Steric strain by interaction of the axial cyclopentadienyl and methyl ligands at Zr and P, respectively, causes these rings to be considerably flattened.