Theoretical exploration of the mechanisms on the iron complexes catalyzed ammonia borane dehydrogenation and polyaminoborane formation

Abstract

Density functional theory study was carried out to provide mechanistic insights into the bifunctional iron complex [Fe(DCPE)(PhNCH2)2 (DCPE = 1,2-bis(dicyclohexylphosphino)ethane)] catalyzed AB dehydrogenation and polyaminoborane formation with the detailed mechanistic pathways. Computational results imply a favorable scenario that complies with a proton transfer pathway between the metal center and ligand, which could further lead to a kinetically feasible transition state with low energy barrier. Subsequent polyaminoborane formation involves the generation of nucleophiles, and the NH2BH2 moiety, which is featured with a nitrogen lone pair, plays a crucial role in the chain polyaminoborane formation. Natural bond orbital analysis (NBO), and energy decomposition analysis (EDA) were utilized to study the orbital interactions and intramolecular weak interactions were revealed by the independent gradient model based on Hirshfeld partition method (IGMH).