The structures of identical and nonlinear Cu2plus;pairs in Yhyphen;type zeolites have been studied by EPR spectroscopy. The identical pairs are formed by exchangehyphen;coupled Cu2plus;ions which have the same symmetry axis and magnetic parameters. They are formed by coexchanging Cu2plus;with Mg2plus;, Ca2plus;, or La3plus;ions into a NaY zeolite. The spectrum is characterized by a zero field splitting ofDequals;0.0476 cmminus;1. The nonlinear pairs which are formed upon more extensive Cu2plus;exchange have symmetry axes that form an angle of 110deg; with respect to each other. These models compare favorably with the available xhyphen;ray diffraction data on CuY zeolites.
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