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

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; SmI 2 -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 ( E 0 ) of a Mo–N bond are also developed.