Energetics and Mechanism of a Room‐Temperature Catalytic Process for Ammonia Synthesis (Schrock Cycle): Comparison with Biological Nitrogen Fixation

Abstract

The transformation of N2 to 2 NH3 on a MoIII complex containing a sterically shielding triamidoamine ligand is investigated with the help of DFT calculations, providing the energy profile and mechanism of the first truly catalytic process of ammonia synthesis working under ambient conditions and proceeding via well‐defined intermediates (see catalytic cycle). It is shown that ammonia synthesis with this artificial system works with an energy expenditure comparable to that of biological nitrogen fixation.

Die katalytische Reduktion von Distickstoff zu Ammoniak mit Molybdän: Theorie und Experiment

“…Die Pyridinium-Säure hat einen großen Einfluss auf den Verlauf der N 2 -Reduktion: [ (11). [48,68] 3…”

A theoretical evaluation of possible transition metal electro-catalysts for N2reduction

“…The energy input needed for articial processes is estimated to be as large as for the biological N 2 xation [20]. For the electro-catalytic N 2 reduction, various types of electrolytes and electrode materials have been tried, but the kinetics are too slow for practical applications [21,22,23,24,25,26,27,28].…”

Functionalization of Dinitrogen Using a Historically Significant Ru Complex: A New Life for an Old Complex

“…Based on these results we propose reduction to be first step in the catalytic cycle ( Figure 2) (which is contrary to that proposed for the Chatt and Schrock catalytic cycle) and construct a different thermodynamic energy profile for all transformations with combinations of different electron and proton sources (Figures 3, 4 and Figures S1-S8 in the Supporting Information) similar to that reported for the Chatt and Schrock catalytic cycle. [16] Combination of Cu with LutH + shows feasible thermodynamic barriers to produce two equivalents of ammonia and hydrazine from 1 (Figures 3 and 2). [20] Complex 1 is susceptible to reduction (1.43 kcal/mol) to yield 2.…”

“…Reduction of 7 and elimination of ammonia (N-N cleavage) is exergonic in nature (-11.87 kcal/mol) which is a similar situation to that calculated for the Schrock system. [16] Protonation of [Ru(NH 3 ) 5 (13) is exergonic (-19.2 kcal/mol). In 13, replacement of ammonia by dinitrogen to yield 1 is more endergonic.…”

“…The calculated endergonic steps (1-3, 4-6, and 11-12 in Figure 3) are within the permissible range of thermodynamically feasible reactions. [16,17] The calculated www.eurjic.orgthermodynamic barriers revealed that there is a possibility of functionalizing the dinitrogen in 1, which has been considered as an inert complex for the last 45 years. We have also examined other reaction pathways.…”