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Why are Hydrogen Bonds Directional?

Shahi, Abhishek and Arunan, Elangannan (2016) Why are Hydrogen Bonds Directional? In: JOURNAL OF CHEMICAL SCIENCES, 128 (10). pp. 1571-1577.

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Official URL: http://dx.doi.org/10.1007/s12039-016-1156-3

Abstract

The recent IUPAC recommendation on the definition of hydrogen bonding points out that directionality is a defining characteristic of a hydrogen bond and the angle a X-H-Y is generally linear or 180(ay). It also suggests that the X-Hai-Y angle be greater than 110(ay) for an interaction to be characterized as a hydrogen bond but does not provide any rationale for the same. This article reports a rationale for limiting the angle, based on the electron density topology using the quantum theory of atoms in molecules. Electron density topology for common hydrogen bond donors HF, HCl, HBr, HNC, HCN and HCCH are reported in this work. These calculations lead to an interesting observation that the atomic basins of H atom in all these donor molecules are limited justifying the restriction of hydrogen bond angle. Moreover, similar analysis on some hydrogen bonded complexes confirms that beyond this angle the acceptor atom Y starts interacting with the atomic basin on X. However, conclusions based on bond lengths and angles have to be treated with care and as the IUPAC recommendation points out that independent `evidence for bond formation' in every case is important.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the INDIAN ACAD SCIENCES, C V RAMAN AVENUE, SADASHIVANAGAR, P B #8005, BANGALORE 560 080, INDIA
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Depositing User: Id for Latest eprints
Date Deposited: 07 Dec 2016 05:07
Last Modified: 07 Dec 2016 05:07
URI: http://eprints.iisc.ac.in/id/eprint/55480

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