Synthesis and Reactivity of a Low-Coordinate Iron(II) Hydride Complex: Applications in Catalytic Hydrodefluorination

A low-coordinate iron hydride complex bearing an unsymmetrical NpN (enamido-phosphinimine) ligand scaffold was synthesized and fully characterized. Insertion reactivity with azobenzene, 3-hexyne, and 1-azidoadamantane was explored, and the isolated products were analogous to previously reported beta-diketiminate iron hydride insertion products. Surprisingly, the NpN iron hydride displays unprecedented reactivity toward hexafluorobenzene, affording an NpN iron fluoride complex and pentafluorobenzene as products. The NpN iron hydride is a pre-catalyst for catalytic hydro-defluorination of perfluorinated aromatics in the presence of silane. Kinetic studies indicated that the rate-determining step during catalysis involved silane.