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The crystal structures of Co2+ and Ag+ exchanged zeolite A, Ag6Co3-A(a = 12.131(5)Å) and Ag3Co4.5-A(a = 12.145(1)Å), have been determined by single crystal X-ray diffraction techniques. Both structures were solved and refined in the cubic space group Pm3m at 21(1)℃. Full-matrix leastsquares refinement converged to the final error indices of R1 = 0.045 and R2 = 0.041 for Ag3Co4.5-A, and R1 = 0.066 and R2 = 0.076 for Ag6Co3-A using the 258 and 189 reflections, respectively, for which I > 3σ(I). Both structures indicate that CO(Ⅱ)ions are coordinated by three framework oxygens; the Co(Ⅱ) to O(3) distances are 2.118(4)Å for Ag3Co4.5-A and 2.106(1)Å for Ag6Co3-A, respectively. In each structure, the angle substended at Co(Ⅱ), O(3)-Co(Ⅱ)-O(3) is ca 120°, close to the idealized trigonalplanar value. Co2+ ions prefer to 6-ring sites and Ag+ ions prefer to 8-ring site when total number of cations is more than 8. The crystals of hydrated and dehydrated Ag12-2xCox-A (x > 4.5) had no crystalline diffraction pattern, indicating the apparent exchange limit of Co2+ into Ag12-A is 4.5 Co2+ ions per unit cell. Co2+ ions hydrolyze H2O molecules and H3O+ concentraction is accumulating. These H3O+ ions destroy the zeolite structures.
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