An Effect of Deuteration on Ion Motions and Hydrogen Bondings in Guanidinium Tetrafluoroborate

Authors:

• Jan Wąsicki,
• Asja Kozak,
• Zdzisław Pająk

Abstract

The fluorine spin-lattice relaxation time as well as NMR second moment for perdeuterated guanidinium tetrafluoroborate were studied over a wide range of temperature. An analytical solution of a set of coupled differential equations describing the time variation of nuclear magnetisations for four unlike spin systems was applied to analyse all cross-relaxation effects in the compound Activation parameters E_a^F=19.3 kJ/mole and τ^F₀ = 9. 10⁻¹⁴s for the isotropic anion reorientation were derived. A coupling of rotational modes of cation and anion was found. Significant lowering of the melting point explained by a weakening of the hydrogen bonds involves diminishing of the ion activation energies due to the large positive isotope effect. © 1992, Verlag der Zeitschrift für Naturforschung, All rights reserved.