Triplet Spin Excitons in a Sigma-Bonded TCNQ Dimer Salt: N-Ethylphenazinium TCNQ, (NEP⁺)₂(TCNQ⁻-TCNQ⁻)

Abstract

Abstract The title compound NEP-TCNQ crystallizes with θ-bonded (TCNQ−-TCNQ−)-dimers. We show by model calculations and ESR spectroscopy, that these bonds can be broken by thermal activation. The reverse reaction occurs spontaneously. The excited states are characterized as quasi immobilized triplet spin excitons (TSE) localized on the two “parts” of the former TCNQ-dimer. Additional weaker TSE and doublet signals are observed.