| Abstract
| - The local environments of Cu(I)−NO adsorption complexes formed in zeolites Cu−L and Cu−ZSM-5 werestudied by electron spin resonance (ESR), pulsed electron nuclear double resonance (ENDOR), and hyperfinesublevel correlation spectroscopy (HYSCORE). Cu(I)−NO complexes have attracted special interest becausethey are important intermediates in the catalytic decomposition of nitric oxide over copper exchanged zeolites.Recently, detailed structures of the complexes in Cu−ZSM-5 zeolites, O2−Al−O2−Cu(I)−NO, have beenproposed on the basis of quantum chemical calculations (Pietrzyk, et al. J. Phys. Chem. B2003, 107, 6105.Dědeček, et al. Phys. Chem. Chem. Phys.2002, 4, 5406). 27Al pulsed ENDOR and HYSCORE experimentsallowed the hyperfine coupling parameters of an aluminum nuclei found in the vicinity of the Cu(I)−NOcomplex formed in zeolite Cu−L to be estimated. The data indicate that the aluminum atom is located in thethird coordination sphere of the adsorbed NO molecule in agreement with the suggested geometry of theadsorption sites. Broad distributions of aluminum nuclear quadrupole and hyperfine coupling parameters andshort electron spin relaxation times of the Cu(I)−NO species prevented the determination of the 27Al hyperfinecouplings for zeolite Cu−ZSM-5.
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