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Nitrogen Fixation Catalyzed by Dinitrogen‐Bridged Dimolybdenum Complexes Bearing PCP‐ and PNP‐Type Pincer Ligands: A Shortcut Pathway Deduced from Free Energy Profiles
Author(s) -
Egi Akihito,
Tanaka Hiromasa,
Konomi Asuka,
Nishibayashi Yoshiaki,
Yoshizawa Kazunari
Publication year - 2020
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201901160
Subject(s) - chemistry , pincer movement , catalysis , protonation , trifluoromethanesulfonate , reactivity (psychology) , density functional theory , catalytic cycle , molybdenum , photochemistry , medicinal chemistry , stereochemistry , computational chemistry , inorganic chemistry , organic chemistry , medicine , ion , alternative medicine , pathology
Density‐functional‐theory (DFT) calculations are carried out for the proposal of a theoretically‐plausible reaction pathway for nitrogen fixation catalyzed by dinitrogen‐bridged dimolybdenum complexes bearing pincer‐type PCP and PNP ligands. The free energy profiles of the entire reaction pathway calculated with a dispersion‐corrected functional provide a catalytic mechanism energetically more efficient than the previously proposed one [Nat. Commun. 2014, 5, 3737]. In the newly‐proposed mechanism the dinuclear Mo–N≡N–Mo structure should be maintained during the catalytic cycle. Despite the coordination of the triflate group with a strong electron‐withdrawing ability, dinitrogen coordinated to a Mo I center has higher reactivity with a proton donor than that coordinated to an electron‐rich Mo 0 center. The calculated results enable us to propose a shortcut pathway in which the regeneration of the dimolybdenum Mo 0 Mo 0 complex is not required. Intermetallic electron transfer between the two Mo centers induced by protonation effectively enhances the reactivity of coordinate N 2 with a proton donor. Our calculations reveal that the synergy of the Mo centers at the protonation step is essential for the catalytic performance of the dimolybdenum system.