THE STRUCTURE OF A CARBON-MONOXIDE ADDUCT OF ZEOLITE-5A

The structure of Ca//5Na//2-A: 5CO has been determined at room temperature using Rietveld profile refinement in space group Fm3c with a refined to 24. 6558(2) Angstrom. The final R//p//w was 3. 5%. As in the case of dehydrated zeolite 5A, the exchangeable cations are located in S1 (6-ring) sites, with Ca-O and Na-O distances of 2. 32 and 2. 37 Angstrom. The carbon atoms of the carbon monoxide molecules have been located on the three-fold axis in the alpha -cage in a position analogous to that found in the CO complex of cobalt-exchanged zeolite A. However, the oxygen atoms are either undergoing considerable thermal motion or are disordered over several off-axis locations.