An Exploration of the Hydrogen Bond Donor Ability of Ammonia

• Published in: Chemphyschem 2023-10, Vol.24 (20), p.e202300382-e202300382
• Main Authors: Pal, Dhritabrata, Chakraborty, Shamik
• Format: Article
• Language: English
• Subjects: Ammonia; Chalcogen bonds; Chemical bonds; Electronic structure; Hydrogen bonds; Protons; Reaction mechanisms
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.202300382

Ammonia is an important molecule due to its wide use in the fertiliser industry. It is also used in aminolysis reac- tions. Theoretical studies of the reaction mechanism pre- dict that in reactive complexes and transition states, am- monia acts as a hydrogen bond donor forming N-H· · ·O hydrogen bond. Experimental reports of N-H· · ·O hydro- gen bond, where ammonia acts as a hydrogen bond donor are scarce. Herein, the hydrogen bond donor ability of ammonia is investigated with three chalcogen atoms i.e. O, S, and Se using matrix isolation infrared spectroscopy and electronic structure calculations. In addition, the chalco- gen bond acceptor ability of ammonia has also been inves- tigated. The hydrogen bond acceptor molecules used here are O(CH3 )2 , S(CH3 )2 , and Se(CH3 )2 . The formation of the 1:1 complex has been monitored in the N-H symmet- ric and anti-symmetric stretching modes of ammonia. The nature of the complex has been delineated using Atoms in Molecules analysis, Natural Bond Orbital analysis, and En- ergy Decomposition Analysis. This work presents the first comparison of the hydrogen bond donor ability of ammonia with O, S, and Se.