SYNTHESIS AND STRUCTURE OF NEW CHIRAL FERROCENYLPHOSPHINES FOR ASYMMETRIC CATALYSIS

The reaction of (R)-1-[(S)-(diphenylphosphino)ferrocenyl]ethyl acetate (1) or R)-1-[(S)-(diphenylphosphino)ferrocenyl]ethylamine (2a) with s econdary phosphines in acetic acid leads to the diphosphines 5 in mode rate to good yields. Two of these ligands, (R) = ylphosphino)ferroceny l]ethyl-dicyclohexylphosphine (5a) and ferrocenyl]ethyl-phenyl-(2-meth oxyphenyl)phosphine (5g), as well as the complexes [Rh(5a)(NBD)]BF4.2C H2Cl2 (9), [Pd(eta3-C3H5) (5a)]OTf (10) and [PtCl2(5a)] (11), have bee n characterized by X-ray diffraction. Crystals of 5a, 9, 10 and 11 are orthorhombic, space group P2(1)2(1)2(1), with four molecules in the u nit cell. 5a: a = 10.772(1), b = 15.278(1), c = 21.069(2) angstrom; 9: a = 18.166(2), b = 17.540(2), c = 14.564(1); 10: a = 10.995(4), b = 1 4.021(8), c = 25.410(11) angstrom; 11: a = 15.077(14), b = 15.122(16), c = 16.188(11) angstrom. The stereogenic-at-phosphorus derivative 5g crystallizes in the monoclinic system, space group P2(1), with two pai rs of symmetry independent molecules per the unit cell with a = 7.896( 1), b = 25.667(2), c = 15.654(1) angstrom and beta = 92.39(1)-degrees. Very similar conformations of the chelate rings in the complexes 9-11 are observed, this being indicative of the relative rigidity of the l igand 5a.