The 77Se high-resolution NMR in the single crystals of potassium and rubidium hydrogen selenites

Solid-state selenium-77 NMR

“…Potassium hydrogen selenite and RbHSeO 3 are isomorphous systems whose structures contain centrosymmetric ðHSeO À 3 Þ 2 dimers. Single crystals of MHSeO 3 (M = K, Rb) were studied by 77 Se NMR, and it was observed that the single HSeO À 3 selenium environment had a significantly different asymmetry parameter, g r , than that found for H 2 SeO 3 [213]. Structures of the MH 3 (SeO 3 ) 2 salts are not as symmetrical as the MHSeO 3 systems and solid-state 77 Se NMR investigations have identified two signals corresponding to HSeO À 3 and H 2 SeO 3 environments within the crystal structure [213][214][215].…”

“…Single crystals of MHSeO 3 (M = K, Rb) were studied by 77 Se NMR, and it was observed that the single HSeO À 3 selenium environment had a significantly different asymmetry parameter, g r , than that found for H 2 SeO 3 [213]. Structures of the MH 3 (SeO 3 ) 2 salts are not as symmetrical as the MHSeO 3 systems and solid-state 77 Se NMR investigations have identified two signals corresponding to HSeO À 3 and H 2 SeO 3 environments within the crystal structure [213][214][215]. While a large difference in g r was found only between the selenium nuclei of HSeO À 3 and H 2 SeO 3 components for (NH 4 )H 3 (SeO 3 ) 2 , it was noted that the shielding anisotropy, Dr, is smaller for the biselenite than in the selenous acid site for all MH 3 (SeO 3 ) 2 (M = NH 4 , K, Cs) [213][214][215].…”

“…Structures of the MH 3 (SeO 3 ) 2 salts are not as symmetrical as the MHSeO 3 systems and solid-state 77 Se NMR investigations have identified two signals corresponding to HSeO À 3 and H 2 SeO 3 environments within the crystal structure [213][214][215]. While a large difference in g r was found only between the selenium nuclei of HSeO À 3 and H 2 SeO 3 components for (NH 4 )H 3 (SeO 3 ) 2 , it was noted that the shielding anisotropy, Dr, is smaller for the biselenite than in the selenous acid site for all MH 3 (SeO 3 ) 2 (M = NH 4 , K, Cs) [213][214][215]. Solid-state 77 Se NMR has also been used to monitor the paraelectric-antiferroelectric transition in CsH 3 (SeO 3 ) 2 as evidenced by the doubling of the unit cell resulting in two HSeO À 3 and two H 2 SeO 3 selenium chemical shift tensors, as given in Table 12 [215].…”