Abstract

BEDT-TTF (ET) and cyananilic acid (H₂CNAL) afforded charge transfer crystals by a diffusion method. The chemical formula of the complex was deduced based on all the information concerning the elemental, structural, electric, magnetic and optical analyses. The ET molecules form one-dimensional columnar stacks composed of twisted dimers with a face-to-face overlap (α′-type stack). The acid works as an oxidant and is deprotonated to form the monoanion, HCNAL¹⁻, which forms ribbon-like aggregation by means of hydrogen-bonds. The ribbons form anion layers that sandwich the ET layer. The crystal is semiconductive with a room temperature conductivity of 0.20–0.83 Scm⁻¹ and activation energy of 0.15 eV along the stacking direction, though the band calculation by the extended Hückel method suggests a metallic nature, indicating strong electron-correlation in this system. The complex is a Mott insulator and its magnetic susceptibility is described by the one-dimensional S = 1//₂ antiferromagnetic Heisenberg chain model with J/k_B = −52 ± 3 K.