Nuclear Quadrupole Coupling Tensors

By single crystal NMR the nuclear quadrupole coupling constants eQ,.h~ (H), the asymmetry parameters >/(H) and the dircetion cosines of the principal axes of the electric field gradient tensors of the H atoms of the two kinds of D 2 0 molecules have been determined at 295 K in RbAl(S04)2 • 1 2 D 2 0 . The results show that the D 2 0 molecules surrounding the ion Al + are "static" within the time scale of the H nuclear quadrupole interaction while the D 2 0 belonging to the octahedron around the Rb + undergoes fast reorientations around the twofold molecular axis. For the two kinds of D 2 0 in the alum we found: e Q Q l V h ' 1 (H) = 186.5 kHz, >7(H) = 0.1234; e Q ^ z V / J ~ 1 (H) = 169.7 kHz, T7(H) = 0.1297; eQ?fh~ (H) = 122.1 kHz, (H) = 0.8087. eQ&iV; and eQ<Pz belong to the "static" D 2 0 molecules and an assignment to the two different H atoms has been performed. The IR spectra of RbAl(S0 4 ) 2 • 12(H t _ ;cD ;<.)20 have been investigated, and for the O D stretching frequencies values of 2145 c m " 1 , 2235 cm" 1 , 2470 c m " 1 and 2525 cm 1 have been obtained. They agree well with the relations between vOD and eQ<P,.h' (H) given in the literature.