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- Title
N<sub>2</sub> Reduction versus H<sub>2</sub> Evolution in a Molybdenum‐ or Tungsten‐Based Small‐Molecule Model System of Nitrogenase.
- Authors
Junge, Jannik; Engesser, Tobias A.; Tuczek, Felix
- Abstract
Molybdenum dinitrogen complexes have played a major role as catalytic model systems of nitrogenase. In comparison, analogous tungsten complexes have in most cases found to be catalytically inactive. Herein, a tungsten complex was shown to be supported by a pentadentate tetrapodal (pentaPod) phosphine ligand, under conditions of N2 fixation, primarily catalyzes the hydrogen evolution reaction (HER), in contrast to its Mo analogue, which catalytically mediates the nitrogen‐reduction reaction (N2RR). DFT calculations were employed to evaluate possible mechanisms and identify the most likely pathways of N2RR and HER activities exhibited by Mo‐ and W‐pentaPod complexes. Two mechanisms for N2RR by PCET are considered, starting from neutral (M(0) cycle) and cationic (M(I) cycle) dinitrogen complexes (M=Mo, W). The latter was found to be energetically more favorable. For HER three scenarios are treated; that is, through bimolecular reactions of early M‐NxHy intermediates, pure hydride intermediates or mixed M(H)(NxHy) species.
- Subjects
MOLYBDENUM; NITROGENASES; HYDROGEN evolution reactions; NITROGEN; TUNGSTEN
- Publication
Chemistry - A European Journal, 2023, Vol 29, Issue 13, p1
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.202202629