Metallic behavior stable against Peierls instability in the one-dimensional organic conductor tetraselenotetracene-bis(1,2,5-thiadiazolo)tetracyanoquinodimethane [(TSeT)-(BTDA-TCNQ)]

Tetraselenotetracene (TSeT) forms a charge-transfer complex with bis(1,2,5-thiadiazolo)tetracyanoquinodimethane (BTDA-TCNQ), the complex showing a metallic behavior down to 1.5 K without undergoing a Peierls transition. The structure consists of segregated columns of TSeT and BTDA-TCNQ molecules, among which there also exist short intermolecular contacts. The polarized reflectance spectra indicate that the material is a one-dimensional metal in contrast to the structural features. The electronic structure is characterized by a one-dimensional conduction band lying on the two-dimensional lattice, which prevents the system from undergoing a Peierls distortion.