Theoretical Investigation into Thermodynamics and Electronic Structure of an Ammonia-productive Molybdenum-centered Catalyst

Jiawei Xu; Pu Yang; Like Deng; Na Shu; Yunlong Shang; Wanjie Zhou; Jianchun Bao; Min Fang; Yong Wu

doi:10.1021/acs.inorgchem.1c00975

Theoretical Investigation into Thermodynamics and Electronic Structure of an Ammonia-productive Molybdenum-centered Catalyst

Inorg Chem. 2021 Aug 16;60(16):11878-11882. doi: 10.1021/acs.inorgchem.1c00975. Epub 2021 Aug 4.

Authors

Jiawei Xu¹, Pu Yang¹, Like Deng¹, Na Shu¹, Yunlong Shang¹, Wanjie Zhou¹, Jianchun Bao¹, Min Fang^{1

2

3}, Yong Wu¹

Affiliations

¹ School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China.
² Jiangsu Key Laboratory of Numerical Simulation of Large Scale Complex System, Nanjing 210023, China.
³ State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210023, China.

PMID: 34347464
DOI: 10.1021/acs.inorgchem.1c00975

Abstract

The N-N bond structure of the key intermediate in the reported catalytic ammonia production (Nature 2019, 568, 536-540) should be described as containing a N-N double bond, instead of containing a N-N triple bond. Two 3c-delocalized bonds are found in this fragment. The analysis of the oxidation states reveal that the N reduction is achieved mainly during the step of N-N bond cleavage; SmI₂-ROH reduction steps reduce Mo atoms and add protons to N atoms without changing their oxidation states. The catalytic cycle is thermodynamically investigated using the DFT method, revealing that the rate-determining step is the reductive formation of the first N-H bond and the nitrogen reduction occurs mainly in the N-N cleavage step. In addition, linear relationships between vibrational stretching frequencies, effective nuclear charges (Z*), and bond dissociation energy (E₀) of a Mo-N bond are also developed.