Crystal Structure and Mechanism of Ag+ Exchange on NaA-NaNO3 Inclusion Complex of Zeolite A

The crystal structure of AgNO 3 inclusion complex of fully Ag + exchanged zeolite A has been determined from three-dimensional Xray data collected with automatic diffractometer. The complex was prepared by the ion-exchange reactions in the AgNO 3 melt. The crystal structure of Ag 12 A·9.5AgNO 3 ·5.9H 2 O inclusion complex was refined in the cubic space group Pm3m, at 24 °C, the unit cell constant is 12.313(1) A. In the resulting structure, 8 Ag + ions per unit cell are on threefold axes in two positions near the center of S6R. Another 5 Ag + cations per unit cell are found at sites near the D4R. The rest of the Ag + cations are situated in the S8R and on the fourfold axes in α and β cages. Four nitrate groups are found on the threefold axes, opposite and near the S6R. The rest of the nitrate groups are statistically distributed near the S8R and in the center of α cage. On the basis of i.r. and X-ray structure analysis it is concluded that nitrate groups in the α cage exist partly as a nitrate ion and partly as a nitrato-complex. Full-matrix least-square refinement converged to an R factor of 11.03 %.