| Abstract
| - The effects of high pressures (up to 40 kbar) on the dihydrogen-bonded BH3NH3 molecular crystal wereinvestigated using Raman spectroscopy in diamond and moissanite anvil cells. The stretching mode frequenciesof the NH3 proton donor groups exhibited moderate red shifts with increasing pressures, as found in manyconventional hydrogen-bonded systems of weak to medium strength. The stretching modes corresponding tothe BH3 proton acceptor group, on the other hand, showed large blue shifts with increasing pressure, which,however, are not related to the changes in the N−H···H−B interactions. The BH3NH3 crystals undergo apressure-induced disorder−order phase transition around 8 kbar, which is facilitated by the presence ofdihydrogen bonds.
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