AN INFRARED STUDY OF TRIMETHYLAMINE OXIDE, ITS HYDRATE, AND ITS HYDROCHLORIDE

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Abstract
The infrared spectra of trimethylamine oxide, its hydrate, and its hydrochloride in the solid state were measured over the range 300 to 3500 cm−1 to ascertain the nature of the bonds in these compounds. From the observed stretching frequencies, 937 cm−1 for N—O and 945 cm−1 for C—N, the corresponding bond lengths are calculated to be 1.44 and 1.50 Å in agreement with X-ray and electron diffraction data. Both these frequencies remain unchanged in the hydrate and the hydrochloride as could be expected for molecular compounds. However, in the hydrochloride most of the evidence points to an ionic constitution. In both the hydrate and the hydrochloride the hydrogen bonds are particularly strong presumably because of the formal charges.