Factors influencing the 17O quadrupole coupling constant in bridging oxygen environments.

Ab initio calculations were performed on the series of clusters [(OH)3M-O-M(OH)3](-2) where M = B, Al, and Ga, (OH)3M-O-M(OH)3 where M = C, Si, and Ge, (OH)2OM-O-MO(OH)2 where M = P and As, and (OH)O2M-O-MO2(OH) where M = S and Se. These clusters were constructed to model the effect of changing the coordinating cation and coordinating cation-oxygen distances on the bridging oxygen 17O quadrupole coupling constant. For all clusters studied, we observed a general trend that the magnitude of Cq increases linearly with increasing cation-oxygen bond distance and cation group number, suggesting that group number and cation-bridging oxygen distance can serve as a better predictor of the bridging oxygen quadrupole coupling constant than electronegativity differences.