Compressed hydrogen-bond effects in the pressure-frozen chloroacetic acid

Abstract

The competing effects of squeezed OH...O bonds, destabilizing the H-atom position, and of displaced hydrogen donor and acceptor groups, favouring the ordered H-atom sites, have been tuned by pressure in the pressure-frozen dichloroacetic acid. Its structure has been determined at 0.1, 0.7, 0.9 and 1.4 GPa: in this pressure range the crystals are stable in the monoclinic space group P2(1)/n. The molecules are O-H...O hydrogen bonded into dimers, which in turn interact via a unique pattern of halogen...halogen contacts. Between 0.1 and 1.4 GPa the OH...O bond is squeezed from 2.674 (13) to 2.632 (9) A. Within the pressure range investigated the hydrogen bonds are squeezed and the shear displacement of the molecules compensate, and the H atoms remain ordered.

Molecular structure, hydrogen bonding and spectroscopic properties of the complex of piperidine-4-carboxylic acid with chloroacetic acid

“…These data confirm the role of ClÁÁÁH contacts in the molecular association in crystal. Analogous contacts have been observed in simple halogenated alcohols [18][19][20][21][22].…”

Pressure effects on H-ordering in hydrogen bonds and interactions in benzoic acid

“…1 High pressure does not change this preference in formic and acetic acids. 44,45 However, chloroacetic acid forms R 2 2 (8) dimers, 46 while bromochlorofluoroacetic acid aggregates into zigzag catemers and dimers depending on the pressure of crystallization. 47 The unit-cell compression up to 2.21 GPa (Fig.…”

A computational study of the cooperativity in clusters of interhalogen derivatives

“…The possibility that the electron density distribution of the halogen atom presents a ''polar flattening'' has been proposed by Gajda and Katrusiak [20,79,80] based on a X-ray study of dichloroacetic acid under pressure. It was observed that one of the ClÁÁÁCl distances (the most linear one) decreases from 3.813 Å (0.1 GPa) to 3.442 Å (1.4 GPa).…”