Water molecular motion and hydrogen bond in paramagnetic [Cu(H2O)(6)][PtCl6] as studied by single crystal H-2 NMR

The temperature and angular dependences of the H-2 NMR spectrum were measur ed for single crystal [Cu(H2O)(6)][PtCl6]. (e(2)Qq/h, eta) = (132 kHz, 0.72 ) were obtained for the D nucleus averaged by the fast 180 degrees flip of the water molecule at 297 K. D-1(236 kHz, 0.10) and D-2(246 kHz, 0.09) were obtained for two unequal D nuclei of the water molecule at 133 K. Below T- c, at least three nonequivalent waters were found to exist. The jumping rat e for the 180 degrees flip of the water molecule (k) was obtained from the simulation of H-2 NMR spectra at H0\\[111] direction. The activation energy E-a and the jumping rate at infinite temperature were estimated from the t emperature dependence of k to be 24kJmol(-1) and 1 x 10(13)s(-1).