An EPR/ENDOR study of the reduction products of symmetrical isomers of dipyridylacetylene

Abstract

The reduction potentials of the three symmetrical isomers (para–para, ortho–ortho and meta–meta) of dipyridylacetylene were measured by cyclic voltametry. These compounds were reacted on alkali metal mirrors and the resulting radical anions were studied by electron paramagnetic resonance/electron–nuclear double resonance/triple resonance spectroscopies. The reduction products were identified after comparison of the measured hyperfine couplings with those predicted by density functional theory calculations. The mono-radical anion was observed for the two former isomers [coupling with the counter ion was detected for the ion pair (ortho–ortho)^-39K⁺]; the third isomer led to the radical anion of dipyridylethylene.

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