SYNTHESIS AND CHARACTERIZATION OF RH(P(CH3)3)2(CO)CH3 AND RH(P(CH3)3)2(CO)PH

The new complexes Rh(P(CH3)3)2(CO)CH3 and Rh(P(CH3)3)2(CO)Ph were synt hesized from Rh(P(CH3)3)2(CO)CI. The phenyl complex was synthesized by two routes, first by direct substitution of Rh(P(CH3)3)2(CO)CI Using diphenylmagnesium and second from the methyl derivative Rh(P(CH3)3)2(C O)CH3 by irradiation in the presence of benzene. Rh(P(CH3)3)2(CO)Ph re acts with HCI at low temperature to form the octahedral complex Rh(P(C H3)3)2(CO)(H)(Cl)Ph, which is unstable for extended periods at tempera tures above 250 K and eliminates benzene to give Rh(P(CH3)3)2(CO)CI (t 1/2 = 12.3 min at 265 K). The structures of Rh(P(CH3)3)2(CO)CI, Rh(P(C H3)3)2(CO)CH3, and Rh(P(CH3)3)2(CO)Ph were determined by X-ray crystal lography. All three complexes are square-planar. Rh(P(CH3)3)2(CO)CH3 h as a Rh-CH3 bond length of 2.130(9) angstrom, and Rh(P(CH3)3)2(CO)Ph h as a Rh-C(phenyl) bond length of 2.096(4) angstrom. Crystals of Rh(P(C H3)3)2(CO)Cl are orthorhombic, space group Pcab, with a = 11.523(2) an gstrom, b = 11.807(2) angstrom, c = 19.843(2) angstrom, V = 2699.7(6) angstrom3, and Z = 8. Crystals of Rh(P(CH3)3)2(CO)CH3 are monoclinic, space group P2(1)/n, with a = 9.944(5) angstrom, b = 10.136(3) angstro m, c = 13.266(6) angstrom, beta = 94.06(4)-degrees, V = 1334(1) angstr om3, and Z = 4. Crystals of Rh(P(CH3)3)2(CO)Ph are monoclinic, space g roup C2/c, with a = 13.406(6) angstrom, b = 11.797(4) angstrom, c = 11 .033(7) angstrom, beta = 109.57(2)-degrees, V = 1644(2) angstrom3, and Z = 4.