Dynamics of cyclohexadienyl radicals in NaZSM-5 and LiZSM-5

Abstract

The dynamics of the muonium substituted cyclohexadienyl radical adsorbed on NaZSM-5 and LiZSM-5 was investigated. Avoided-level-crossing muon spin resonance studies revealed extensive surface-sorbate interactions and showed a strong effect of the nature of the metal dopants on the radical mobility.

Complexation of Copper by Cyclohexadienyl Radicals in Cu/ZSM-5 Zeolite

“…Similar results were obtained in preliminary experiments with LiZSM-5, where the Δ 0 (Li + ) resonance shifted to ca. 1.72 T, and with NaZSM-5 where the Δ 0 (Na + ) line is observed at 1.69 T . In all cases where metal cations are present the lines narrow considerably when the temperature is raised above 300 K, which indicates that the complexed species is also not rigidly fixed to the zeolite lattice.…”

Muon Spin Spectroscopy of Transient Radicals in Zeolites

“…The endo and exo orientations of the C 6 H 6 Mu radical give rise to two different muon hfcc because coupling to the Na + distorts the cyclohexadienyl radical from planarity and causes the muon and the methylene proton to be inequivalent. Additional resonances in LiZSM-5 and NaZSM-5 suggest that the cyclohexadienyl radical can also form complexes with Li + and Na + cations [24]. The breadth of the resonances and the absence of significant temperature dependence indicate that the motion of the radical is extremely limited.…”