Chemical Shift Prediction in the 29Si MAS NMR of Titanosilicates

• Published in: The journal of physical chemistry. B Vol. 102; no. 16; pp. 2897 - 2904
• Main Authors: Labouriau, Andrea, Higley, T. J, Earl, William L
• Format: Journal Article
• Language: English; Japanese
• Published: American Chemical Society 16.04.1998
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp9716703

We have related the 29Si MAS NMR chemical shifts of titanosilicates and highly siliceous zeolites linearly with structural factors. Good correlations in titanosilicates were obtained using the model proposed by Sherriff et al., , where the chemical shift is described in terms of the summation of valence, dipole, and hybridization terms. This empirical correlation provides a basis for semiquantitative interpretation of spectra for titanium-bearing silicates. Our original goal was to understand the lack of a 29Si NMR peak assignable to silicon that is next-nearest neighbor to titanium in titanium-containing zeolites. Although the equations and correlations presented work very well for most titanium-containing silicates, we still do not understand the 29Si MAS NMR spectrum of these zeolites because our results suggest that there should be a distinguishable peak for TS-1 and TS-2. No such peaks are detected in the actual spectra.