Oxidative additions to stable five-co-ordinate d8 complexes: bis[1,2-bis(diphenylphosphino)ethane]- and bis[1,2-bis(diphenylphosphino)ethylene]-(isocyanide)iridium(I) complexes

Abstract

The stable, five-co-ordinate, cationic species [Ir(CNR)L₂]⁺[R = Me or p-MeC₆H₄; L = 1,2-bis(diphenylphosphino)ethane (dppe) or 1,2-bis(diphenylphosphino)ethylene (dppen)] undergo oxidative addition of proton acids (including methanol), halogens, and HgCl₂without loss of a ligand to give dicationic adducts [IrY(CNR)L₂]²⁺(Y = H, Cl, I, or HgCl), but do not react with alkyl, allyl, or acyl halides. Proton acids give cis-adducts under kinetic control which may then isomerize on heating. Dihydrogen and dioxygen react very slowly to give cis-[IrH₂L₂]⁺ and [Ir(O₂) L₂]⁺, respectively and SO₂ gives an unstable adduct which dissociates at room temperature even in liquid SO₂.