Dehydrogenation of Iron Amido-Borane and Resaturation of the Imino-Borane Complex

We report on the first isolation and structural characterization of an iron phosphinoimino-borane complex Cp*Fe(η2-H2BNC6H4PPh2) by dehydrogenation of iron amido-borane precursor Cp*Fe(η1-H3B–NHC6H4PPh2). Significantly, regeneration of the amido-borane complex has been realized by protonation of the iron(II) imino-borane to the amino-borane intermediate [Cp*Fe(η2-H2B–NHC6H4PPh2)]+ followed by hydride transfer. These new iron species are efficient catalysts for 1,2-selective transfer hydrogenation of quinolines with ammonia borane.