Carbon-oxygen bond formation on rhodium centers. Synthesis, characterization, crystal structure, and reactions of trans-PhORh(CO)(PPh sub 3 ) sub 2

The synthesis of a rhodium phenoxide is reported. The complex trans-PhORh(CO)(PPh{sub 3}){sub 2} crystallizes in the centrosymmetric monoclinic space group P2{sub 1}/c with a = 15.794 (3) {angstrom}, b = 11.449 (2) {angstrom}, c = 20.025 (3) {angstrom}, {beta} = 100.220 (13){degree}, V = 3,562 (1) {angstrom}{sup 3}, and Z = 4. Diffraction data (Mo K{alpha}, 2{theta} = 4.5-50.0{degree}) were collected with a Syntex P2{sub 1} diffractometer, and the structure was refined to R{sub F} = 2.8% for 5,293 reflections. The structure is isomorphous with the iridium analogue. Important dimensions include Rh-P = 2.337 (1)-2.357 (1) {angstrom}, Rh-CO = 1.801 (3) {angstrom} Rh-OPh = 2.044 (2) {angstrom}, and Rh-O-C(phenoxide) = 1.25.52 (19){degree}. This complex reacts with Ph{sub 2}CHC(O)Cl to give the ester Ph{sub 2}CHC(O)OPh and with MeI to give anisole, PhOMe. The formation of anisole from the rhodium phenoxide is in contrast to the failure to eliminate ethers from similar iridium complexes and is consistent with the known preference for elimination from second-row (rather than third-row) transition-metal complexes.