Nuclear magnetic resonance spectra of the high-temperature solid phase of tetra-n-hexyl ammonium perchlorate

Abstract

High resolution NMR (proton) spectra have been obtained of the solid phase of tetra-n-hexyl ammonium perchlorate between 364 and 379 K. Since it is well known that high resolution spectra cannot be obtained on true solids, the existence of four well-defined resonances (associated with the protons adjacent to the nitrogen, adjacent removed by one carbon, attached to three internal carbons and the terminal methyl protons) indicates that the hydrocarbon chains must exist in a state of free rotation. In the same temperature range (367.51 to 379.18 K) the ammonium and perchlorate positions are restricted to lattice points. A technique for the accurate measurement of temperature within the Varian HA100 NMR spectrometer is described. It is proposed as a result of the NMR study that the high temperature phase exists as a special case (ionic) of the plastic crystalline state. A search of the literature indicates that several other tetra-alkyl ammonium salts may exhibit the same phenomena. © 1976.