Iridium Dimer Anion-Mediated C≡C Triple Bond Cleavage and Successive Dehydrogenation of Acetylene in the Gas Phase.

The reactions of the iridium dimer anion [Ir 2 ] - with acetylene have been studied by mass spectrometry in the gas phase, which indicate that the [Ir 2 ] - anion can consecutively react with C 2 H 2 molecules to form the [Ir 2 C 2 x ] - ( x = 1, 2) and [Ir 2 C 2 y H 2 ] - ( y = 3-5) anions as major products with the successive release of H 2 molecules at room temperature. The reactions are confirmed by the reactions of the mass-selected product [Ir 2 C 2 ] - anion with C 2 H 2 to produce [Ir 2 C 4 ] - and [Ir 2 C 2 y H 2 ] - ( y = 3-5). Photoelectron spectra and quantum chemistry calculations confirm that the [Ir 2 C 2 x ] - ( x = 1, 2) product anions possess cyclic [Ir(μ-C) 2 Ir] - and [Ir(μ-C)(μ-C 3 )Ir] - structures, implying that the robust C≡C triple bond of acetylene can be completely cleaved by the [Ir 2 ] - anion.