Synthesis and migratory insertion reactions of (vinylidene)iridium complexes trans-[IrX(= C = CRR ') (PiPr(3))(2)] containing alkyl, aryl, alkynyl, and azide ligands

The (vinylidene)iridium(I) complexes trans-[IrCl(=C=CRR')(PiPr(3))(2)] (1, 4) react with organolithium compounds R " Li by chloride substitution to af ford the organoiridium(I) derivatives trans-[IrR "(=C=CRR')(PiPr(3))(2)] (5 -8) in excellent yields. In contrast, treatment of 1 (R = SiMe3, R' = Me) w ith Grignard reagents R " MgX leads to halide metathesis and formation of t he bromo- and iodoiridium(I) compounds trans-[IrX{=C=C(SiMe3)Me}(PiPr(3))(2 )] (X = Br, I), respectively. The alkynyl complexes trans-[Ir(C=CR)(=C=CHPh )(PiPr(3))(2)] (R = Ph, CO2Me) are obtained by an acid-base reaction from t rans-[Ir(OH)(=C=CHPh)(PiPr(3))(2)] and the free alkyne. Treatment of compou nds 5-8 and 12 with CO initiates a migratory insertion process which gives the eta(1)-vinyl complexes trans-[Ir{eta(1)-(Z)-C(R ")=CRR'}(CO)(PiPr(3))(2 )] (13-17) in nearly quantitative yields. Acid-induced cleavage of the Ir-C sigma-bond of 13, 14, and 17 with CH3CO2H or CF3CO2H affords trans-[Ir(eta (1)-O2CR)(CO)(PiPr(3))(2)] and the corresponding olefin. The preparation of the fluoroiridium(I) derivative trans-[IrF(=C=CHPh)(PiPr(3))(2)] (26) has been achieved either from trans-[Ir( OH)(=C=CHPh)(PiPr(3))(2)] and NEt3. 3H F or from trans-[Ir(eta(1)-O2CCF3)(=C=CHPh)(PiPr(3))(2)] and [nBu(4)N]F. Th e azidoiridium(I) compounds trans-[IrN3(=C=CHR)(PiPr(3))(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 cy ano-substituted alkyl complexes trans-[Ir{CH(CN)R)(CO)(PiPr(3))(2)] (32, 33 ) and N-2. The molecular structure of trans-[Ir{eta(1)-(Z)-C(Me)=C(SiMe3)Me }(Co)(PiPr(3))(2)] (13) has been determined by X-ray crystallography.