CONFORMATION OF BEDT-TTF MOLECULES IN THE CRYSTAL

Based on comparison of low-temperature x-ray diffraction data for BEDT-TTF salts and quantum chemical MNDO calculations, we have shown that the most energetically favorable conformation of the BEDT-TTF molecule is not realized in the crystal. A local energy minimum 0. 035 e V above the ground state corresponds to the conformation detected in the crystal. The x-ray diffraction data and the MNDO results suggest weak participation of the heteroatoms of the six-membered rings in the conjugation with the pi-system of the TTF-fragment in the BEDT-TTF and BEDO-TTF molecules.