Strongly hydrogen-bonded molecular complexes studied by matrix isolation vibrational spectroscopy. Part 3.—Ammonia–hydrogen bromide and amine–hydrogen bromide complexes

Abstract

Infrared spectra are reported of strongly hydrogen-bonded complexes between ammonia or amines (methylamine, dimethylamine and trimethyl-amine) and hydrogen bromide trapped in argon and nitrogen matrices. There are substantial differences between the spectra of the complexes in the two matrices, which are attributed to increased proton transfer from hydrogen bromide to the amine in the more polar nitrogen matrix. The extent of proton transfer increases from ammonia–hydrogen bromide in an argon matrix (where the proton is shared more or less equally between the nitrogen and bromine atoms) to trimethylamine–hydrogen bromide in a nitrogen matrix (where the proton is almost completely transferred to the amine).