Catalytic Reduction of Dinitrogen to Ammonia by Use of Molybdenum–Nitride Complexes Bearing a Tridentate Triphosphine as Catalysts

Abstract

Newly designed and prepared molybdenum-nitride complexes bearing a mer-tridentate triphosphine as a ligand have been found to work as the most effective catalysts toward the catalytic reduction of dinitrogen to ammonia under ambient conditions, where up to 63 equiv of ammonia based on the Mo atom of the catalyst were produced.

Catalytic Nitrogen Fixation via Direct Cleavage of Nitrogen–Nitrogen Triple Bond of Molecular Dinitrogen under Ambient Reaction Conditions

“…We have now found that molybdenumiodide complexes bearing a PNP-pincer ligand have a higher catalytic activity than the so far reported molybdenumdinitrogen complexes 29,35 for ammonia formation from nitrogen gas under ambient reaction conditions, up to 830 equiv being produced based on the dinitrogen-bridged dimolybdenum complex (415 equiv of ammonia based on the molybdenum atom). This remarkable catalytic activity is realized by a novel reaction pathway, where the generation of a dinitrogen-bridged dimolybdenumiodide complex is a key point to promote direct cleavage of nitrogen nitrogen triple bond of the bridging dinitrogen ligand in the MoN¸NMo core.…”

“…As described in the present manuscript, molybdenumiodide complexes bearing a PNP-pincer ligand such as 1a and 2a have a higher catalytic activity than the so far reported molybdenum dinitrogen complexes 29,35 for ammonia formation from nitrogen gas under ambient reaction conditions, up to 830 equiv being produced based on a dinitrogen-bridged dimolybdenum complex (415 equiv of ammonia based on the molybdenum atom). If the formation of ammonia by using molybdenumiodide complexes as catalysts proceeds via the same reaction pathway, where 3 worked as a catalyst (Path A in Figure 1a), we cannot explain this remarkable catalytic activity of molybdenumiodide complexes, the higher TONs and TOFs of 1a than those of 3 and the higher selectivity of 1a than that of 3 toward the formation of ammonia prior to hydrogen gas (Table 1 and Figure 3).…”

A Synthetic Single-Site Fe Nitrogenase: High Turnover, Freeze-Quench 57Fe Mössbauer Data, and a Hydride Resting State

“… Data for Mo1-H and Mo2 are from reference 11 and depictions of the compounds are presented in Chart 1. a Conditions: 2,6-lutidinium trifluoromethanesulfonate and cobaltocene in toluene. b Conditions: 2,4,6-trimethylpyridinium trifluoromethanesulfonate and decamethylcobaltocene in toluene. c Conditions: HBAr F 4 and KC 8 in diethyl ether. d Expressed in NH 3 equivalents. …”

“… Data for Mo1-H and Mo2 are from reference 11 and depictions of the compounds are presented in Chart 1. …”

Silylation of Dinitrogen Catalyzed by Hydridodinitrogentris(Triphenylphosphine)Cobalt(I)

“…Catalytic formation of ammonia on well-defined systems was pioneered by the group of Schrock who developed a molybdenum-based system that catalyzed the formation of almost eight equivalents of NH3 per metal atom [19]. The group of Nishibayashi developed binuclear catalysts which were able to catalyze the formation of up to 63 equivalents of NH3 per Mo atom [20,21]. Iron also proved to be catalytically active as shown by the group of Peters, whose catalysts could produce up to 64 equivalents of NH3 at very low temperatures [22,23].…”