Insertion and other reactions of some hydridoolefin complexes of iridium(I)

A family of complexes IrH(CO)(Ph 3 P) 2 (ol), where ol is a monosubstituted ethylene, has been synthesized. Under an inert atmosphere the acrylonitrile complex undergoes clean decomposition to produce C 2 H 5 CN, half of the necessary hydrogen for the ligand reduction apparently being furnished by the phosphine ligand. The first step in the hydrogénation is insertion of the unsaturated ligand into the IrH bond. The alkyl product is unstable but may be trapped by O 2 , to give the alkyl dioxygen complex, or by excess acrylonitrile to give the α-cyanoethyl acrylonitrile complex. Other ligands, such as CO and phosphines, displace the olefinic ligand more rapidly than insertion occurs. When ol = sytrene, the complex is very unstable with respect to styrene dissociation and very little insertion is observed. Under O 2 , the styrene complex gives the first known hydridodioxygen complex IrH(CO)(PPh 3 ) 2 (O 2 ). The methyl acrylate complex exhibits behavior intermediate between that of the styrene and acrylonitrile analogues.