FORMATION OF CARBON-CARBON BONDS ON DI(ORGANO)IRIDIUM COMPLEXES, RR'Ir(CO)(PPH3)2X (R,R' = Me, Ph, CH2Ph, C(O)CH3; X = Cl, I) AND THE CRYSTAL STRUCTURE OF cis,cis,trans-

Article abstract of DOI:10.1016/0022-328X(87)80372-8

The reactions of RX with trans-R'Ir(CO)(PPh3)2 are reported.Addition of CH3C(O)Cl to trans-CH3Ir(CO)(PPh3)2 leads to acetone; addition of CH3I to trans-PhIr(CO)(PPh3)2 leads to toluene; and addition of CH3I to trans-C6H5CH2Ir(CO)(PPh3)2 leads to ethylbenzene.Reaction of C2H5Br with trans-CH3Ir(CO)(PPh3)2 leads to CH4 and C2H4.The addition of CH3I to trans-CH3Ir(CO)(PPh3)2 leads to Ir(CH3)2Ir(CO)(PPh3)2I from which Ir(CH3)2(CO)2(PPh3)2(1+) and Ir(CH3)2(CO)(PPh3)2(1+) can be prepared.These dimethyl complexes do not undergo reductive elimination of ethane, acetone or diacetyl under a variety of conditions (CH4 and C2H6 are formed at decomposition).Thus for these complexes the charge, the presence of a free coordination site and the cis stereochemistry do not facilitate reductive elimination reactions.To ascertain that no structural features were preventing reductive elimination from the dimethyl complex we have examined the structure of cis,cis,trans-.This crystallizes in the centrosymmetric triclinic space group P<*> (C¹_i; No. 2) with a 11.708(2), b 11.738(2), c 14.702(2) Angstroem, α 87.544(13), β 79.181(14), γ 76.963(15)deg, V 1933.4(6) Angstroem³ and D(calc'd) 1.64 g cm^-3 for mol. wt. 951.9 and Z = 2.X-ray diffraction data (Mo-K_α, 2θ 4.5-50.0deg) were collected with a Syntex P2₁ automated four-circle diffractometer and the structure was refined to R 3.5percent for all 6835 reflections (R 2.9percent for those 6133 reflections with <*>F₀<*> > 6?(<*>F₀<*>)).The central d⁶ iridium(III) ion has a slightly distorted octahedral stereochemistry, with Ir-CO 1.943(5) and 1.956(5) Angstroem, Ir-CH3 2.152(5) and 2.155(5) Angstroem and Ir-PPh3 2.391(1) and 2.400(1) Angstroem; interligand angles include OC-Ir-CO 102.09(20), CH3-Ir-CH3 89.70(19) and PPh3-Ir-PPh3 174.68(4)deg.