X-RAY-ABSORPTION STUDIES OF ZNCL2-PEO AND MIXED SALT ZNCL2 KCL-PEO AND ZNCL2/CSCL-PEO COMPLEXES/

ZnCl2[polyethylene oxide (PEO)](12), [0.33 ZnCl2 + 0.67 KCl](PEO)(12), and [0.33 ZnCl2 + 0.67 CsCl](PEO)(12) complexes were studied by x-ray absorption in the temperature range of 25 to 120 degrees C. The resul ts for ZnCl2(PEO)(12) show that the complex exists mostly as undissoci ated ZnCl2 with the Zn atom also coordinated with four O atoms from th e PEO. The respective Zn-Cl and Zn-O bond distances are 2.2 and 2.05 A ngstrom. There is an increase in ion pairing with increasing temperatu re. The results for the mixed salt complexes are consistent with the f ormation of a mixture of ZnCl42- and ZnCl3- complexes with a Zn-Cl bon d distance of similar to 2.26 Angstrom. Complex formation differs in [ 0.33 ZnCl2 + 0.67 KCl](PEO)(12) and [0.33 ZnCl2 + 0.67 CsCl](PEO)(12). This is attributed to the higher charge density of K+, which promotes ion pairing and shifts the ZnCl42-/ZnCl3- equilibrium.