An Unprecedented Iridium(III) Catalyst for Stereoselective Dimerisation of Terminal Alkynes

A novel iridium(III) hydride complex, IrHCl(TIMP₃) {HTIMP₃=tris[1‐(diphenylphosphino)‐3‐methyl‐1H‐indol‐2‐yl]methane} was prepared and fully characterized in both the solid state and in solution. Chloride abstraction by silver cations provides a more reactive compound, [IrH(TIMP₃)][BF₄], which can react with pyridine (py) and phenylacetylene to yield the complexes [IrH(TIMP₃)(py)][BF₄] and [Ir(PhCHC CHCHPh)(TIMP₃)][BF₄], respectively. Interestingly, IrH(TIMP₃)(py)][BF₄] efficiently catalyses the stereoselective dimerisation of model terminal alkynes to the 1,4‐disubstituted (E)‐but‐1‐en‐3‐yne only.