Synthesis and structural characterisation of Group 11 metal complexes with a phosphinoferrocene oxazoline†
The coordination properties of phosphinoferrocene oxazolines with Group 11 metal ions were probed through a series of reactions between various metal precursors and the model ligand, rac-1-[4,5-dihydro-4,4-dimethyl-2-oxazolyl]-2-(diphenylphosphino)ferrocene (1). The reactions of 1 with CuX and AgCl produced the halide-bridged dimers [M(μ-X)(1-κ2N,P)], where M/X = Cu/Cl (2a), Cu/Br (2b), Cu/I (2c), and Ag/Cl (3), whereas the reaction with [AuCl(tht)] (tht = tetrahydrothiophene) yielded the chlorogold(I) complex [AuCl(1-κP)] (4). When metal precursors without strongly coordinating halide ligands were used (viz., [Cu(MeCN)4][PF6] and AgClO4), the complexation reactions generated bis-chelate complexes [M(1-κ2N,P)2]X (5: M/X = Cu/PF6, 6: M/X = Ag/ClO4). A similar reaction with [Au(tht)2]ClO4 produced [Au(1-κP)2]ClO4 (7), wherein the gold centre is linearly coordinated by two phosphine moieties. All complexes except for 4 were structurally authenticated by X-ray crystallography. The observed coordination behaviour and structures of the isolated complexes are discussed in the context of the catalytic properties of chiral ligands structurally related to the model compound 1.