Synthesis and reactivity of new bis(N-heterocyclic carbene) iridium(I) complexes.

New complexes of the type trans-[IrCl(η(2)-COE)(NHC)2] (COE = cis-cyclooctene; NHC = N-heterocyclic carbene) have been prepared in one step from the reaction of ca. 4 equiv of NHC or [AgCl(NHC)] with [IrCl(η(2)-COE)2]2 in benzene. These new complexes have been characterized by techniques including NMR and IR spectroscopy, X-ray crystallography, and elemental analysis. Exposing trans-[IrCl(COE)(I(i)Pr(Me))2] to CO yielded trans-[IrCl(CO)(I(i)Pr(Me))2], which is the only bis(NHC) analogue of Vaska's complex trans-[IrCl(CO)(PPh3)2] known to date. The synthesis of trans-[Ir(CO)(I(i)Pr(Me))2(R)] (R = MeO, PhCC, OSiPh3, O2CPh) complexes has been achieved via deprotonation reactions involving the new hydroxide species trans-[Ir(OH)(CO)(I(i)Pr(Me))2].