Electron spin resonance spectroscopy of radical cations and anions of methylated biphenylenes, tetraphenylene, and octa-β-methyltetraphenylene

Abstract

Octa-β-methyltetraphenylene has been prepared in low yield by the thermolysis of tetra-β-methyl-biphenylene.

The radical cations and radical anions of tetra-α-methylbiphenylene, tetra-β-methylbiphenylene, and octamethylbiphenylene, and the radical cation of octa-β-methyltetraphenylene have been generated and their ESR spectra have been recorded and analysed. In trifluoroacetic acid containing mercury(II) trifluoroacetate, the tetra-α-methylbiphenylene radical cation undergoes mono- and dimercuriation. Tetra-β-methylbiphenylene in tetrahydrofuran in the presence of lithium apparently undergoes ring-opening to give a radical anion derived from 2,2′-dilithiobiphenyl. The structures which these spectra imply, particularly the apparent distortion which has been reported in the tetraphenylene radical anion, are discussed.