E-Selective Semi-hydrogenation of Alkynes with Dinuclear Iridium Complexes under Atmospheric Pressure of Hydrogen

Semi-hydrogenation of alkynes was catalyzed by halide-bridged dinuclear iridium complexes, yielding (E)-alkenes with high selectivity. Mechanistic studies conducted with mono hydride dinuclear species, dihydride mononuclear species, and trihydride dinuclear species led us to propose a mechanism involving dual cycles.