Temperature-dependent hyperfine splitting constants in the electron spin resonance spectra of some thienylmethanone radical anions

Abstract

The radical anions of di-2-thienyl- and phenyl-2-thienyl-methanone have been prepared by electrochemical reduction in dimethylformamide, dimethyl sulphoxide, and acetonitrile. The e.s.r. spectrum of the former has been interpreted in terms of the presence of both the trans,trans- and cis,trans-conformers, and the activation parameters for the interconversion between these conformers have been determined. The temperature dependence of the hyperfine splitting constants in each conformer has also been determined, and in dimethylformamide reveals a temperature-independent region between 263 and 293 K. The individual conformers were not observed for the phenyl-2-thienylmethanone radical anion.