17O NMR Spectroscopy of α-TeO2 and Na2TeO3
The synthesis of 17O-enriched α-tellurite (α-TeO2) is described. TeO2 is obtained stochiometrically by the reaction of tellurium isopropoxide with 17O-enriched H2O. The reaction is mild and simple and opens the field of tellurite-based ceramics to 17O nuclear magnetic resonance spectroscopy. We also report the first 17O nuclear magnetic resonance spectra of α-TeO2 and Na2TeO3. Their isotropic chemical shifts, iso, are 180 ppm and 158 ppm, respectively, and their quadrupolar coupling parameters are CQ=7.48 MHz and =0.43 for α-TeO2, and CQ=6.63 MHz and =0.33. By using extended Hückel tight binding calculations, we interpret the chemical shifts of tetravalent inorganic oxide network formers (SiO2, GeO2, and TeO2) in terms of the local paramagnetic shielding effect. We also show that this is the predominant effect in determining the chemical shifts of non-bridging oxide sites in this type of network.
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Document Type: Research Article
Affiliations: Department of Chemistry, Indiana University, Bloomington, Indiana 47405
Publication date: 2005-08-01