Geometrical Analysis to Understand the Ability of Halogen Atoms to Act as Hydrogen-Bond Acceptors: A Structural Database Study

Abstract

Abstract Non-covalent interactions involving halogen atoms play a major role in supramolecular chemistry, biochemistry, coordination and organometallic chemistry and also act as conformation-determining factors. Therefore, the hydrogen-bonding nature of the halogen acceptors in solid state are analyzed statistically, and the geometrical characteristics of weak hydrogen-bonded interactions are studied for the oxygen, nitrogen, and carbon atom donors. The hybridization states of the donor atoms and the different coordination environment of the halogen acceptors were also considered. The distance and the directionality characteristics that dictate the hydrogen bonds are given importance. Oxygen and nitrogen donors both showed the ability to form a strong hydrogen bond whereas carbon donors formed weak hydrogen bonds. The hydrogen-bonding nature of the carbon donor with a halogen acceptor was proven with this analysis; however, it had a hydrogen···acceptor distance cutoff of 2.7 Å for chlorine. Different hybridization states of the donor atoms did not significantly change the nature of the interaction; however, various coordination environments had some effect.