Low-Valent Ene–Amido Iron Complexes for the Asymmetric Transfer Hydrogenation of Acetophenone without Base

Examination of the role of base in the activation of our previously reported iron(II) complexes having the general formula [Fe(CO)(Br)(PNNP)][BPh4] revealed a five-coordinate iron(II) complex in which the tetradentate PNNP ligand had been doubly deprotonated. The new iron(II) complexes were used in the transfer hydrogenation of acetophenone in isopropanol in the absence of added base, and certain analogues showed catalytic activity.