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)1[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.