Reactions of carbon monoxide with trans-Ir(CO)(Cl)(TPPMS)2 (TPPMS = PPh2(C6H4SO3K)) in DMSO and water, rate and mechanistic studies

Reaction of CO with trans-Ir(CO)(Cl)L-2 (L=PPh3 in toluene and DMSO; L=TPPMS in DMSO and H2O, TPPMS = PPh2(m-C6H4SO3Na)) reversibly produces Ir(CO)(2)(Cl)L-2 or [Ir(CO)(3)L-2]Cl depending on the solvent polarity. The solvent polarity has a small effect on the rate of reaction with CO; the rate constants in toluene, DMSO and H2O are all within a factor of two. Comparison to the reaction with H-2 shows that the selectivity for CO is much greater (k(CO)/k(H2) = 150) in toluene than in water (k(CO)/k(H2) = 5).