NUCLEAR-QUADRUPOLE COUPLING TENSORS OF H-2 IN THE ALPHA-ALUM RBAL(SO4)2.12D2O AND THE DYNAMIC BEHAVIOR OF THE D2O MOLECULES - AN INVESTIGATION BY NMR AND IR

By single crystal NMR the nuclear quadrupole coupling constants [formula omitted], the asymmetry parameters η(2H) and the direction cosines of the principal axes of the electric field gradient tensors of the 2H atoms of the two kinds of D2O molecules have been determined at 295 K in RbA1(SO4)2 · 12D2O. The results show that the D2O molecules surrounding the ion Al3+ are “static” within the time scale of the 2H nuclear quadrupole interaction while the D2O belonging to the octahedron around the Rb+ undergoes fast reorientations around the twofold molecular axis. For the two kinds of D2O in the alum we found: [formula omitted] and [formula omitted] belong to the “static” D2O molecules and an assignment to the two different 2H atoms has been performed. The IR spectra of RbAl(SO4)2 · 12(H1-xDx)2O have been investigated, and for the O–D stretching frequencies values of 2145 cm−1, 2235 cm−1, 2470 cm−1 and 2525 cm−1 have been obtained. They agree well with the relations between and [formula omitted] given in the literature. © 1990, Verlag der Zeitschrift für Naturforschung. All rights reserved.