Premium
Theoretical Investigation on the Chemistry of Entrapment of the Elusive Aminoborane (H 2 NBH 2 ) Molecule
Author(s) -
Malakar Tanmay,
Bhunya Sourav,
Paul Ankan
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201405543
Subject(s) - chemistry , cyclohexene , nucleophile , hydroboration , borane , molecule , dehydrogenation , reaction mechanism , computational chemistry , medicinal chemistry , photochemistry , stereochemistry , catalysis , organic chemistry
Aminoborane (H 2 NBH 2 ) is an elusive entity and is thought to be produced during dehydropolymerization of ammonia borane, a molecule of prime interest in the field of chemical hydrogen storage. The entrapment of H 2 NBH 2 through hydroboration of exogenous cyclohexene has emerged as a routine technique to infer if free H 2 NBH 2 is produced or not during metal‐catalyzed ammonia borane dehydrogenation reactions. But to date, the underlying mechanism of this trapping reaction remains unexplored. Herein, by using DFT calculations, we have investigated the mechanism of trapping of H 2 NBH 2 by cyclohexene. Contrary to conventional wisdom, our study revealed that the trapping of H 2 NBH 2 does not occur through direct hydroboration of H 2 NBH 2 on the double bond of cyclohexene. We found that autocatalysis by H 2 NBH 2 is crucial for the entrapment of another H 2 NBH 2 molecule by cyclohexene. Additionally, nucleophilic assistance from the solvent is also implicated for the entrapment reaction carried out in nucleophilic solvents. In THF, the rate‐determining barrier for formation of the trapping product was predicted to be 16.7 kcal mol −1 at M06 L(CPCM) level of theory.