Solid State Properties of Charge Transfer Complexes of TTF Derivatives with 3D-Transition Metal Halides

Abstract
We investigated structure, electronic and magnetic properties of organic conductors with 3d-transition metal halide anions. The crystal structure investigation in (TTM-TTF)CuBr4shows a novel type of nonplanar TTM-TTF2+ structure. Suscep tibilities obey the Curie's law, suggesting the absence of magnet ic interactions between Cu2+magnetic moments. (BEDT-TTF)6Cu2Br6 is a two-dimensional conductor with the mixed valence state of Cu2+/Cu+. A structural transition with a first order nature is found at TC=59K, which is related to the defor mation of CuBr4 2-ligand. The application of pressure modifies the transition to a metal-semiconductor one. An antiferromag-netic long range order accompanied by a short range order is observed at TN=7.5K. This suggests the presence of strong antiferromagnetic interactions achieved by the coupling between Cu2+ localized moments and donor π -electrons.