An S = 1 / 2 Iron Complex Featuring N 2 , Thiolate, and Hydride Ligands: Reductive Elimination of H 2 and Relevant Thermochemical Fe-H Parameters

• Published in: Journal of the American Chemical Society Vol. 140; no. 20; pp. 6374 - 6382
• Main Authors: Gu, Nina X, Oyala, Paul H, Peters, Jonas C
• Format: Journal Article
• Language: English
• Published: United States 23-05-2018
• Subjects: Ferric Compounds - chemical synthesis; Ferric Compounds - chemistry; Hydrogen - chemistry; Ligands; Models, Molecular; Molybdoferredoxin - chemical synthesis; Molybdoferredoxin - chemistry; Nitrogen - chemistry; Oxidation-Reduction; Sulfhydryl Compounds - chemical synthesis; Sulfhydryl Compounds - chemistry; Temperature; Thermodynamics
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.8b02603

Believed to accumulate on the Fe sites of the FeMo-cofactor (FeMoco) of MoFe-nitrogenase under turnover, strongly donating hydrides have been proposed to facilitate N
binding to Fe and may also participate in the hydrogen evolution process concomitant to nitrogen fixation. Here, we report the synthesis and characterization of a thiolate-coordinated Fe
(H)(N
) complex, which releases H
upon warming to yield an Fe
-N
-Fe
complex. Bimolecular reductive elimination of H
from metal hydrides is pertinent to the hydrogen evolution processes of both enzymes and electrocatalysts, but well-defined examples are uncommon and usually observed from diamagnetic second- and third-row transition metals. Kinetic data obtained on the HER of this ferric hydride species are consistent with a bimolecular reductive elimination pathway, arising from cleavage of the Fe-H bond with a computationally determined BDFE of 55.6 kcal/mol.