Low-temperature study of radical cations of quadricyclane and norbornadiene in Na-ZSM-5 zeolites

✍ Scribed by K.R. Cromack; D.W. Werst; M.V. Barnabas; A.D. Trifunac

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 557 KB
• Volume: 218
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(94)00026-3

✦ Synopsis

We have observed quadricyclane and norbomadiene radical cations in different pentasil type zeolites by EPR spectroscopy after 4 K in situ electron beam irradiation of samples in the EPR spectrometer. We report the first evidence for matrix isolation of the quadricyclane radical cation. It is stable in polar Na-ZSM-5 zeolites below 20-30 K. Formation of the bicycle [ 3.2.0]hepta-2,6-diene radical cation is observed in both quadricyclane-and norbomadiene-loaded zeolites. The onset temperature for the formation of the bicycle [ 3.2.0]hepta-2,6-diene radical cation depends on the substrate concentration and zeolite polarity and was as low as 30 K in polar zeolites when the substrate concentration was high.