FORMATION AND CRYSTAL STRUCTURE OF MeIr(CO)(PPh3)2(MeCO2CH=CHCO2Me). COMPARISON OF THE STRUCTURES OF ANALOGOUS ALKENE AND ALKYNE COMPLEXES

Article abstract of DOI:10.1016/0022-328X(86)82059-9

The complex MeIr(CO)(PPh3)2(MeCO2CH=CHCO2Me), synthesized from trans-MeIr(CO)(PPh3)2 and dimethyl maleate, crystallizes in the centosymmetric monoclinic space group P2₁/n with a 13.997(5), b 17.878(5), c 15.709(4) angstroem, β 91.002(2) deg, V 3930(2) angstroem³ and Z=4.X-ray data (Mo-K_α, 2θ 4.5-45.0 deg) were collected with a Syntex P2₁ automated four-circle diffractometer; the structure was solved and converged with R 5.5 percent for all 5069 unique reflections and R 4.3 percent for those 4343 data with The iridium(I) center has a distored trigonal bipyramidal geometry with the Me and CO ligands occupying axial sites (Ir-Me(1) 2.159(8), Ir-CO 1.907(8) angstroem).The MeCO2CH=CHCO2Me ligand is bonded in η² fashion to the iridium, with is coordinated double bond parallel to the equatorial plane.Bonds to the equatorial ligands are Ir-P(1) 2.344(2), Ir-P(2) 2.376(2) and Ir-(center of olefin) 2.017 angstroem.The observed ligand configuration is different from that for MeIr(CO)(PPh3)2(MeCO2CCCO2Me) which has axial Me and PPh3 ligands in its thermodynamically stable isomer.