
TY  - JOUR
A1  - Hamann, SD 
A1  - Spinner, E 
T1  - The effect of pressure on the infrared spectrum of ammonium formate: HCO<sub>2</sub>NH<sub>4</sub>, DCO<sub>2</sub>NH<sub>4</sub>, HCO<sub>2</sub>ND<sub>4</sub>, DCO<sub>2</sub>ND<sub>4</sub>. An unusual intermolecular coupling of non-identical vibrations in phase II
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1977
VL  - 30
IS  - 12
SP  - 2591
EP  - 2596
KW  - 
UR  - https://doi.org/10.1071/CH9772591 
N2  - The infrared spectra of the title compounds have been measured over the pressure range 0-42 kbar at 25°C. The phase change at c. 12 kbar is accompanied by an increase in the NH stretching frequencies and other well-defined spectral changes. Vibrational coupling in phase II of HCO2NH4 between CH in-plane bending in HCO2- and a bending motion in NH4+, and its counterpart for DCO2ND4, account for some unusual frequency changes arising from isotopic substitution in the counter ion. The spectral changes suggest that during the phase change I &#8594; II the NH...O hydrogen bonds are weakened and the cations move to positions in close proximity beside the CH bonds. 
ER  -

