Synthesis and Migratory Insertion Reactions of (Vinylidene)iridium Complexes trans-[IrX(CCRR‘)(PiPr3)2] Containing Alkyl, Aryl, Alkynyl, and Azide Ligands,1

Abstract

The (vinylidene)iridium(I) complexes trans-[IrCl(CCRR‘)(PiPr3)2] (1, 4) react with organolithium compounds R‘ ‘Li by chloride substitution to afford the organoiridium(I) derivatives trans-[IrR‘ ‘(CCRR‘)(PiPr3)2] (5−8) in excellent yields. In contrast, treatment of 1 (R = SiMe3, R‘ = Me) with Grignard reagents R‘ ‘MgX leads to halide metathesis and formation of the bromo- and iodoiridium(I) compounds trans-[IrX{CC(SiMe3)Me}(PiPr3)2] (X = Br, I), respectively. The alkynyl complexes trans-[Ir(C⋮CR)(CCHPh)(PiPr3)2] (R = Ph, CO2Me) are obtained by an acid−base reaction from trans-[Ir(OH)(CCHPh)(PiPr3)2] and the free alkyne. Treatment of compounds 5−8 and 12 with CO initiates a migratory insertion process which gives the η1-vinyl complexes trans-[Ir{η1-(Z)-C(R‘ ‘)CRR‘}(CO)(PiPr3)2] (13−17) in nearly quantitative yields. Acid-induced cleavage of the Ir−C σ-bond of 13, 14, and 17 with CH3CO2H or CF3CO2H affords trans-[Ir(η1-O2CR)(CO)(PiPr3)2] and the corresponding olefin. The preparation of the fluoroiridium(I) derivative trans-[IrF(CCHPh)(PiPr3)2] (26) has been achieved either from trans-[Ir(OH)(CCHPh)(PiPr3)2] and NEt3·3HF or from trans-[Ir(η1-O2CCF3)(CCHPh)(PiPr3)2] and [nBu4N]F. The azidoiridium(I) compounds trans-[IrN3(CCHR)(PiPr3)2] (R = Ph, CO2Me), which are obtained from the related chloro derivatives and excess NaN3, undergo in the presence of CO a migratory insertion reaction to give the cyano-substituted alkyl complexes trans-[Ir{CH(CN)R}(CO)(PiPr3)2] (32, 33) and N2. The molecular structure of trans-[Ir{η1-(Z)-C(Me)C(SiMe3)Me}(CO)(PiPr3)2] (13) has been determined by X-ray crystallography.