On hydrogen bond correlations at high pressures

TL;DR

This study demonstrates that high-pressure neutron diffraction data on hydrogen bonds in various substances follow established correlations from ambient conditions, challenging previous claims of deviation, and explores the behavior of hydrogen bonds under pressure.

Contribution

It provides new experimental evidence that hydrogen bond lengths under high pressure adhere to known correlations, clarifying previous conflicting results and extending understanding of hydrogen bond behavior.

Findings

High-pressure data follow established hydrogen bond correlations.

Contradicts previous claims of deviation in ice VIII.

Links red and blue shift behaviors to hydrogen bond characteristics.

Abstract

In situ high pressure neutron diffraction measured lengths of O H and H O pairs in hydrogen bonds in substances are shown to follow the correlation between them established from 0.1 MPa data on different chemical compounds. In particular, the conclusion by Nelmes et al that their high pressure data on ice VIII differ from it is not supported. For compounds in which the O H stretching frequencies red shift under pressure, it is shown that wherever structural data is available, they follow the stretching frequency versus H O (or O O) distance correlation. For compounds displaying blue shifts with pressure an analogy appears to exist with improper hydrogen bonds.