Synthesis and Structural Characterisation of Palladium and Group-12 Metal Complexes with a Hybrid Phosphanylphosphonate Ferrocene Ligand

✍ Scribed by Petr Štěpnička; Ivana Císařová; Róbert Gyepes

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 295 KB
• Volume: 2006
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/ejic.200500725

✦ Synopsis

Abstract

Diethyl [1′‐(diphenylphosphanyl)ferrocenyl]phosphonate (1) was synthesised by stepwise metallation/functionalisation of 1,1′‐dibromoferrocene and studied as a ligand for palladium(II) and group‐12 metals. Treatment of [PdCl~2~(cod)] (cod = η^2^:η^2^‐cycloocta‐1,5‐diene) with 1 in 1:1 or 1:2 molar ratios gave, respectively, the dinuclear, chloride‐bridged complex [{Pd(μ‐Cl)Cl(1‐κ__P__^2^)}~2~] (2) and the mononuclear complex trans‐[PdCl~2~(1‐κ__P__^2^)~2~] (3), where 1 coordinates exclusively through the phosphane function. The reactions between 1 and group‐12 metal bromides MBr~2~ in a 1:1 molar ratio gave the adducts [MBr~2~(1)] [M = Zn (4), Cd (5), and Hg (6)], whose crystal structures change considerably with the metal ion. Thus, whereas 4 is a molecular complex with 1 coordinating as an O^1^,P^2^‐chelate, its cadmium(II) analogue is a polymer built up from symmetric {CdBr(μ‐Br)}~2~ units interconnected by pairs of O^1^,P^2^‐bridging phosphanylphosphonate ligands. Finally, the mercury(II) complex 6 is a halide‐bridged dimer, [{Hg(μ‐Br)Br(1‐κ__P__^2^)}~2~]. However, this compound is structurally fluxional in solution (NMR spectra) and, in the crystal, it attains a structure similar to 5 owing to weak interactions between mercury and phosphonate‐O^1^ atoms from adjacent molecules. An isomer to 6, [{HgBr~2~(1‐κ^2^O^1^,P^2^)}~2~] (7), was isolated from attempted alkylation of 6 and structurally characterised as a dimer, where ligands 1 bridge two {HgBr~2~} units. All compounds were studied by spectroscopic methods (IR, NMR, mass) and the solid‐state structures of 1, 2·${1 \over 2}$ H~2~O, 3·4 CHCl~3~, 4, 5, 6·5 C~6~H~6~, and 7 have been determined by single‐crystal X‐ray diffraction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)