Identifying the Rate-Limiting Elementary Steps of Nitrogen Fixation with Single-Site Fe Model Complexes

Benedek, Zsolt and Papp, Marcell and Oláh, Julianna and Szilvási, Tibor (2018) Identifying the Rate-Limiting Elementary Steps of Nitrogen Fixation with Single-Site Fe Model Complexes. INORGANIC CHEMISTRY, 57. pp. 8499-8508. ISSN 0020-1669


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Biomimetic nitrogen fixation provides an attractive alternative for the century-old Haber−Bosch process; however, the performance of the currently available molecular biomimetic catalysts is very limited. In this work, we are aiming to understand the catalytic cycle of one of the most promising biomimetic complex families that can be the cornerstone of future computer-aided rational design of biomimetic complexes. We calculate the Gibbs free energy of all elementary reaction steps of homogeneous dinitrogen reduction to NH3 on singlesite iron complexes with EPPP tetradentate ligands (E = B, Si). We examine all possible mechanisms and identify the dominant pathways and the critical elementary steps that can be ratedetermining in the catalytic cycle of nitrogen fixation. We find that the catalytic mechanism depends on the applied ligand and that the distal pathway observed with E = B is the most favorable route regarding the catalytic performance. Our calculations also reveal the lack of thermodynamic driving force in the last steps of the catalytic cycle that can be responsible for the low catalytic activity of the studied biomimetic catalysts. Our results can serve as a starting point for the rational design of biomimetic complexes, which should focus on establishing a steadily decreasing Gibbs free energy profile, as suggested by the Sabatier principle.

Item Type: Article
Subjects: Q Science / természettudomány > QD Chemistry / kémia > QD02 Physical chemistry / fizikai kémia
Q Science / természettudomány > QD Chemistry / kémia > QD03 Inorganic chemistry / szervetlen kémia
Depositing User: Dr. Julianna Oláh
Date Deposited: 11 Sep 2018 13:18
Last Modified: 11 Sep 2018 13:18

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