Interaction of different molecules with Cu2+ cations in CuH-ZSM-5. Electron spin resonance study and quantum-chemical calculations

Abstract

An e.s.r. study of interaction between isolated coordinatively unsaturated Cu²⁺ cations located in dehydroxylated at 1073 K CuH-ZSM-5 and different molecules [NH₃, pyridine, CH₃OH, (CH₃)₂O, C₃H₆, p-xylene] has been carried out. The results obtained are compared with the data of INDO calculations. It is not only the possibility of coordinative complex formation in zeolite channels that must be taken into account when analysing the mechanism of Cu²⁺ interaction with sorbed molecules. A small change in donor–acceptor properties of Cu²⁺ ligand environment and a slight geometric displacement of Cu²⁺ ion in his chelate site may result in a noticeable change in hyperfine structure of the Cu²⁺ e.s.r. signal.