We have obtained static, “magic-angle”, and “variable-angle” sample-spinning 17O NMR spectra of 17O-labeled A, Y, and dealuminated Y zeolites at 67.8 and 48.8 MHz (corresponding to magnetic field strengths of 11.7 and 8.45 T). Our results indicate that the ranges of 17O nuclear quadrupole coupling constants (e2qQ/h) of the SiAl and Si[17O]Si fragments are 3.1-3.2 and 4.6-5.2 MHz, respectively, in general agreement with those predicted on the basis of the empirical correlation presented previously (Schramm, S.; Oldfield, E. J. Am. Chem. Soc. 1984, 106, 2502). The asymmetry parameters are 0.2 for SiAl and 0.1 for Si[17O]Si. The isotropic chemical shifts of the SiAl fragments are in the range of 31–45 ppm relative to H20, while those of the Si[17O]Si fragments are in the range of 44–57 ppm.
ASJC Scopus subject areas
- Colloid and Surface Chemistry