Reduction of Dinitrogen to Ammonia Catalyzed by Molybdenum Diamido Complexes

Abstract

[ArN]Mo(N)(O-t-Bu), which contains the conformationally rigid pyridine-based diamido ligand, [2,6-(ArNCH)NCH] (Ar = 2,6-diisopropylphenyl), can be prepared from H[ArN], butyllithium, and (t-BuO)Mo(N). [ArN]Mo(N)(O-t-Bu) serves as a catalyst or precursor for the catalytic reduction of molecular nitrogen to ammonia in diethyl ether between -78 and 22 °C in a batchwise manner with CoCp* as the electron source and PhNHOTf as the proton source. Up to ∼10 equiv of ammonia can be formed per Mo with a maximum efficiency in electrons of ∼43%.

Influence of a Metal Substrate on Small‐Molecule Activation Mediated by a Surface‐Adsorbed Complex

“…A particularly challenging case is nitrogen fixation, as it involves protonation and reduction of the most inert molecule of the universe, N 2 . Inspired by the biological process of nitrogen fixation, a number of molybdenum, iron, and other transition metal complexes have been synthesized that catalyze the conversion of N 2 to NH 3 in homogeneous solution . Besides proton donors such as HBAr F 4 [Ar F =3,5‐bis(trifluoromethyl)phenyl] and lutidinium salts, these processes require the addition of reducing agents (e.g., decamethylchromocene or KC 8 ) …”

“…[9] Inspired by the biological process of nitrogen fixation, [10] an umber of molybdenum, iron, and other transitionm etal complexes have been synthesized that catalyze the conversionofN 2 to NH 3 in homogeneous solution. [2,3,5,[11][12][13][14][15][16][17][18][19][20] Besides proton donors such as HBAr F 4 [Ar F = 3,5-bis(trifluoromethyl)phenyl] and lutidinium salts, these processes require the addition of reducinga gents (e.g.,decamethylchromoceneorK C 8 ). [2,11,12,15] In the past years, significant effort has been directed towardst he attachment of catalysts activei nH ER, OER, or ORR to metal or semiconductor electrodes with the goal of performing the processes in an electrocatalytic fashion.…”

Catalytic Reduction of Molecular Dinitrogen to Ammonia and Hydrazine Using Vanadium Complexes

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Newly designed and prepared vanadium complexes bearing anionic pyrrole-based PNP-type pincer and aryloxy ligands were found to work as effective catalysts for the direct conversion of molecular dinitrogen into ammonia and hydrazine under mild reaction conditions.This is the first successful example of vanadium-catalyzed dinitrogen reduction under mild reaction conditions. [2] Since the report of the first successful example of molybdenum-catalyzed dinitrogen reduction, [2] some successful examples of catalytic dinitrogen reduction systems using other mid-to-late transition-metal dinitrogen complexes as catalysts have been reported by other research groups. Based on intensive study of the preparation of various transition-metal dinitrogen complexes and their detailed reactivity, [1] Schrock and co-workers discovered adirect and catalytic transformation of molecular dinitrogen into ammonia under ambient reaction conditions using am ononuclear molybdenum dinitrogen complex as ac atalyst.

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“…Based on intensive study of the preparation of various transition-metal dinitrogen complexes and their detailed reactivity, [1] Schrock and co-workers discovered adirect and catalytic transformation of molecular dinitrogen into ammonia under ambient reaction conditions using am ononuclear molybdenum dinitrogen complex as ac atalyst. [2] Since the report of the first successful example of molybdenum-catalyzed dinitrogen reduction, [2] some successful examples of catalytic dinitrogen reduction systems using other mid-to-late transition-metal dinitrogen complexes as catalysts have been reported by other research groups. [3,4] After the seminal report of more-effective molybdenumcatalyzed dinitrogen reduction under ambient reaction conditions, [5] iron-, [6][7][8] cobalt-, [9,10] osmium-, [11] and ruthenium [11] catalyzed dinitrogen reductions under mild reaction conditions have been developed, where av ery low reaction temperature such as À78 8 8Ci sn ecessary to avoid the direct reaction of reducing reagents with proton sources.T he produced amounts of ammonia and hydrazine depend on the nature of the metals,l igands,a nd solvents.H owever, successful examples have been limited to the use of mid-tolate transition-metal complexes as catalysts.Early-transitionmetal-catalyzed dinitrogen reduction under mild reaction conditions has not been reported to date.In sharp contrast to the Haber-Bosch process,which takes place under harsh reaction conditions, [12] biological nitrogen fixation proceeds smoothly under ambient reaction condi-tions.D etailed investigations have revealed that the FeMo nitrogenase has as ulfur-bridged polynuclear complex containing molybdenum, iron, and carbon atoms although the exact reaction mechanism is not yet understood.…”

Electrochemical Reduction of N2 to NH3 Using a Co‐Atom Stabilized on Defective N‐Doped Graphene: A Computational Study

“…[30][31][32][33][34][35] Up to now, various types of SACs have been prepared for the N 2 reduction reaction (NRR), like Mo-nitride complexes, in which a single metal atom coordinated by N atoms (M-N x ) serves as the active catalytic site. [36][37][38][39][40][41][42] Aside from low-cost, long-term durability and environmental benignity, these M-N x show superior catalytic activity due to high carrier mobility arising from their π-electrons, which facilitates the charge transfer in the NRR process. [43][44][45][46][47][48][49] Graphene is a single atomic honeycomb layer of carbon atoms with novel chemical, optical and mechanical properties.…”