CW EPR spectra of tetracyanofurane anion radicals dependent differently on the counter ion. The same tetracyanofurane derivative has been reduced in THF with Na, K, or Cs. All three spectra are different. The resolution of the EPR spectra is higher at lower temperatures between 240-270 K. Therefore, SR experiments have been performed as a function of temperature. The spin-lattice relaxation rate of each sample has a temperature dependence of about T2.5, however the T1s for the various counter ions are different. It is assumed, therefore, that conformation does not change as the temperature decreases. The conformation variation in the tetracyane anion at low temperatures may be due to exchange-narrowing effect or change of the rotational motion. Q-band spectra at 293 K did not have a better resolution than at X-band. Calculations with the program ALCHEMY3 gave at least three different energy minima with almost the same energy, which supports the idea of the counter ion effect.
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