Metal complexes of cyanocarbons XI. Reactions of tetracyanoethylene with hydridoiridium complexes

Abstract

Reactions of tetracyanoethylene(TCNE) with a number of hydrido-complexes of iridium have been studied. Displacement reactions are observed for most of the tervalent, octahedral iridium substrates such as IrHCl 2(CO)(PPh 3) 2, IrH 2Cl(CO)(PPh 3) 2, IrHCl(SnCl 3)CO(PPh 3) 2, and IrH 2(SnCl 3)CO(PPh 3) 2 where HCl, H 2 SnHCl 3, and SnH 2Cl 2 respectively are eliminated and the iridium-containing product in all cases is IrCl(CO)(TCNE)(PPh 3) 2. In the case of the univalent, trigonal bipyramidal substrates IrH(CO)(PPh 3) 3 and IrH(CO) 2(PPh 3) 2 as well as tervalent IrH 3(CO)(PPh 3) 2, a 1,4-addition to TCNE is formally observed, and the novel cyano(dicyanomethyl) keteniminato complex Ir(C 6N 4H)(CO)(TCNE)(PPh 3) 2 is isolated when the solvent is benzene. The presence of alcohol in the reaction mixture results in the formation of the cyano-complex Ir(CN)(CO)(TCNE)(PPh 3) 2 as well as the keteniminato-complex. The nature of the keteniminatoiridium bond is discussed and a rationale for the 1,4-addition is proposed.