A thiolate-bridged Fe IV Fe IV μ-nitrido complex and its hydrogenation reactivity toward ammonia formation.

Iron nitrides are key intermediates in biological nitrogen fixation and the industrial Haber-Bosch process, used to form ammonia from dinitrogen. However, the proposed successive conversion of nitride to ammonia remains elusive. In this regard, the search for well-described multi-iron nitrido model complexes and investigations on controlling their reactivity towards ammonia formation have long been of great challenge and importance. Here we report a well-defined thiolate-bridged Fe IV Fe IV μ-nitrido complex featuring an uncommon bent Fe-N-Fe moiety. Remarkably, this complex shows excellent reactivity toward hydrogenation with H 2 at ambient conditions, forming ammonia in high yield. Combined experimental and computational studies demonstrate that a thiolate-bridged Fe III Fe III μ-amido complex is a key intermediate, which is generated through an unusual two-electron oxidation of H 2 . Moreover, ammonia production was also realized by treating this diiron μ-nitride with electrons and water as a proton source.