ISSN:
0749-1581
Keywords:
NMR
;
205Tl
;
Solid state
;
Zeolites A. X and Y
;
Thallium
;
Frequency-stepped spin-echo integral method (FUSSI)
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Thallium-205 NMR is reported for several zeolite samples (A, X and Y; hydrated and dehydrated) with thallium(I) exchanged for sodium. Detection at high field (7.05 T) clarifies the spectrum appearance, and it is seen that chemical shift anisotropy (CSA) dominates some of the band shapes. The large CSAs dictate that the spectrum is recorded piecewise by a frequency-stepped spin-echo integral (FUSSI) method. Magic-angle sample spinning has been observed to give only a very minor line-narrowing effect. Threefold-coordinated zeolite A Tl+ sites adjacent to six-membered rings [Tl(1) and Tl(3)] are both assigned to a resonance which has large CSA (δiso 1183, δδ - 1842), while the remaining zeolite A site [Tl(2)] gives an isotropic line shape (δiso 300). Dehydrated zeolite X gives an isotropic peak (δiso 854) which is assigned to the double six-ring Tl(I), and a broader anisotropic resonance which is tentatively attributed to supercage Tl(III). Data for dehydrated zeolite Y indicate that this has a disordered cation distribution.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260311207
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