Enhanced Hydrogen Generation from Formic Acid by Half-Sandwich Iridium(III) Complexes with Metal/NH Bifunctionality: A Pronounced Switch from Transfer Hydrogenation.
By switching the catalytic function from transfer hydrogenation based on the metal/NH bifunctionality, facile dehydrogenation of formic acid was achieved by amido- and hydrido(amine)-Ir complexes derived from N-triflyl-1,2-diphenylethylenediamine (TfDPEN) at ambient temperature even in the absence of base additives. Further acceleration was observed by the addition of water, leading to a maximum turnover frequency above 6000 h(-1). A proton-relay mechanism guided by the protic amine ligand and water is postulated for effective protonation of metal hydrides.
Department of Applied Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, O-okayama 2-12-1-E4-1, Meguro-ku, Tokyo 152-8552 (Japan).
Asuka
A
Matsunami
Department of Applied Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, O-okayama 2-12-1-E4-1, Meguro-ku, Tokyo 152-8552 (Japan). ykayaki@o.cc.titech.ac.jp.
Yoshihito
Y
Kayaki
Department of Applied Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, O-okayama 2-12-1-E4-1, Meguro-ku, Tokyo 152-8552 (Japan). tikariya@apc.titech.ac.jp.
Takao
T
Ikariya
cooperative effects; dehydrogenation; homogeneous catalysis; hydride ligands; iridium