Abstract: | The preparation and properties as well as some reactions of a series of arylcarbonylbis(triphenylphosphine)iridium(I) complexes [Ir(Ar)(CO)(PPh3)2] (Ar = C6H5, C6F5, 2-C6H4CH3, 3-C6H4CH3, 4-C6H4CH3, 2-C6H4OCH3, 2,6-C6H3-(OCH3)2, 4-C6H4N(CH3)2, 3-C6H4Cl, 4-C6H4Cl, 4-C6H4Cl, 3-C6H4CF3, 4-C6H4CF3) are described, and the most important IR data as well as the 31P NMR parameters of these, without exception trans-planar, compounds are given. Some of the complexes react with molecular oxygen to form well defined dioxygen adducts [Ir(Ar)(O2)(CO)(PPh3)2] (Ar = C6H5, 3-C6H4CH3, 4-C6H4CH3). Complexes with ortho-substituted aryl ligands are not oxygenated. This effect is referred to as a steric shielding of the metal center by the corresponding ortho-substituents. With SO2 the similar irreversible addition compound [Ir(4-C6H4CH3)-(SO2)(CO)(PPh3)2] is obtained. Sulfur dioxide insertion into the Ir---C bond cannot be observed. The first step of the reaction between [Ir(4-C6H4CH3)(CO)(PPh3)2] and hydrogen chloride involves an oxidative addition of HCl to give [Ir(H)(Cl)(4-C6-H4CH3)(CO)(PPh3)2]. Ir---C bond cleavage by reductive elimination of toluene from the primary adduct does not occur except at elevated temperature. |