Characterization of the SiOT Angle and Cation Effects on 29Si Chemical Shifts Of Zeolites

The quantitative relationships between 29Si chemical shifts and (a) the SiOT (T = Al or Si) angles and (b) the nature of the cations of the alkali forms of zeolites can be account for by the changes of charge density and p electron population of the Si atoms as calculated by the extended Huckel method on cluster models.