Structure and thermal properties

Abstract

The effect on the lattice spacings of substituting deuterium for hydrogen has been investigated for pentaerythritol, CuS0 4 5H 2 0, SrCl 2 6H 2 0, furmaric acid, KH 2 P0 4 , NaHS0 4 , urea, and KHF 2 . The main conclusion is that when the crystal structure contains hydroxyl bonds the isotope effect is small, and when it contains hydrogen bonds there is a marked expansion, which disturbs the lattice sufficiently to lead to the separation of potassium phosphate in a new crystal structure. The effect for potassium hydrogen fluoride does not suggest a short hydrogen bond in this compound. Short hydrogen bonds seem to require special resonance forces for their explanation.