Chiral bisphosphanes: Part XIII. Nickel, palladium and platinum complexes containing optically active cyclopentane-based P2 ligands with phosphorinane and dicyclohexylphosphanyl donor functions, [(1S,2S)-C5H8(PC5H10-cyclo)2MCl2] and [(1S,2S)-C5H8{P(C6H11)

The chelate complexes [(1S,2S)-C5H8(PR2)2MCl2] [PR2=PC5H10-cyclo: M=Ni (1), Pd (2), Pt (3); PR2=P(C6H11)2: M=Ni (4), Pd (5), Pt (6)] were prepared from NiCl2·6H2O, [(η4-1,5-C8H12)PdCl2] or [(Me2SO)2PtCl2] and the required optically active bisphosphane ligand, (1S,2S)-C5H8(PC5H10-cyclo)2 or (1S,2S)-C5H8[P(C6H11)2]2, in order to serve as catalysts for the synthesis of non-racemic 2,2′-dimethyl-1,1′-binaphthyl by asymmetric cross-coupling of 1-bromo-2-methylnaphthalene with its derived Grignard reagent. The coupling reactions generally suffered from low conversion. Nickel complex 4, the crystal structure of which was determined by X-ray diffraction, gave the (R)-(−) form of the C–C coupling product in modest enantiomeric excess (26% e.e.).