Formation of carboncarbon bonds on di(organo)iridium complexes, rr′Ir(CO)(PPh 3) 2X (R,R′ = Me, Ph, CH 2Ph, C(O)CH 3; X = Cl, I) and the crystal structure of cis,cis,trans-[Ir(CH 3) 2(CO) 2(PPh 3) 2+][CF 3SO 3−

Abstract

The reactions of RX with trans-R′Ir(CO(PPh 3) 2 are reported. Addition of CH 3C(O)Cl to trans-CH 3Ir(CO)(PPh 3) 2 leads to acetone; addition of CH 3I to trans-PhIr(CO)(PPh 3) 2 leads to toluene; and addition of CH 3I to trans-C 6H 5CH 2Ir(CO)(PPh 3) 2 leads to ethylbenzene. Reaction of C 2H 5Br with trans-CH 3Ir(CO)(PPh 3) 2 leads to CH 4 and C 2H 4. The addition of CH 3I to trans-CH 3Ir(CO)(PPh 3) 2 leads to Ir(CH 3) 2Ir(CO)(PPh 3) 2I from which Ir(CH 3) 2(CO)-(PPh 3) 2 + and Ir(CH 3) 2(CO) 2(PPh 3) 2 + can be prepared. These dimethyl complexes do not undergo reductive elimination of ethane, acetone or diacetyl under a variety of conditions (CH 4 and C 2H 6 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-[Ir(CH 3) 2(CO) 2(PPh 3) 2 +][CF 3SO 3 −]. This crystallizes in the centrosymmetric triclinic space group P 1 ( C i 1; No. 2) with a 11.708(2), b 11.738(2) c 14.702(2) Å, α 87.544(13), β 79.181(14), γ 76.963(15)°, V 1933.4(6) Å 3 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 4.5–50.0°) were collected with a Syntex P2 1 automated four-circle diffractometer and the structure was refined to R 3.5% for all 6835 reflections ( R 2.9% for those 6133 reflections with | F 0| > 6σ(| F 0|)). The central d 6 iridium(III) ion has a slightly distorted octahedral stereochemistry, with Ir-CO 1.943(5) and 1.956(5) Å, Ir-CH 3 2.152(5) and 2.155(5) Å and Ir-PPh 3 2.391(1) and 2.400(1) Å; interligand angles include OC-Ir_CO 102.09(20), CH 3-Ir-CH 3 89.70(19) and PPh 3-Ir-PPh 3 174.68(4)°.