A Parent Iron Amido Complex in Catalysis of Ammonia Oxidation

摘要

Parent amido complexes are crucial intermediates in ammonia-based transformations. We report a well-defined ferric ammine system Cp*Fe(1,2-Ph2PC6H4NH)(NH3)(+) (1-NH3(+)), which processes electrocatalytic ammonia oxidation to N-2 and H-2 at a mild potential. Through establishing elementary e(-)/H+ conversions with the ferric ammine, a formal Fe(IV)-amido species, 1-NH2(+), together with its conjugated Lewis acid, 1-NH3(2+), was isolated and structurally characterized for the first time. Mechanism studies indicated that further oxidation of 1-NH2(+) induces the reaction of the parent amido unit with NH3. The formation of hydrazine is realized by the non-innocent nature of the phenylamido ligand that facilitates the concerted transfer of one proton and two electrons.