ESTIMATION OF THE ENERGIES OF INTERMOLECULAR INTERACTIONS X...Y (X=BEDT-TTF, TMTSF; Y = C60, C70) IN THE NEW MOLECULAR COMPLEXES OF FULLERENES
S.V.Konovalikhin and L.O.Atovmyan.
Institute of Chemical Physics in
Chernogolovka, Russian Academy of Sciences, Chernogolovka, Moscow
Region, 142432, Russia.
E-mai1 knh@icp.ac.ru
An X-ray study of (BEDT-TTF)2C60 (1) (BEDT-TTF - bis(ethylenedithio)- tetrathiafulvalene) [1], (TMTSF)C602(CS2) (2) (TMTSF - tetralnethyltetraselena-fulvalene) [2] and (TMTSF)2(C60)2(C6H6) (3) [3] crystals has been made It has been established that the conformations of the BEDT-TTF and TMTSF molecules in crystals 1 - 3 are not energetically preferable. It is "boat" conformation. For example: the TMTSF molecules is folded along Se...Se line on 22 - 27o. Usually, the BEDT-TTF and TMTSF molecules has a plane ore near to plane conformation. It has been established that analogous conformation have of TMTSF molecule in the (TMTSF)X(C70)y(C6H6)z (4) crystal [4]. It has been shown that it is caused by is intermolecular interactions X...Y (X= BEDT-TTF, TMTSF; Y = C60, C70). We assume that the energy of these intermolecular interactions (W) can be estimated as it follows from the equation W = Wc- W0, where W0 is the energy of the more energetically preferable conformer of the X molecule, Wc is the energy of the X molecule conformer in crystals 1 - 4. The energies of the conformers of the BEDT-TTF and TMTSF molecules have been calculated by the SCF MO method in the 3-21G/6-31G* basis. It has been established, that the energy of the BEDT-TTF...C60 intermolecular interactions in the (BEDT-TTF)2C60 crystal is 13 kcal/mol. The energy of the TMTSF...C60 intermolecular interactions in the (TMTSF)C60 2(CS2) and (TMTSF)2(C60)2(C6H6) crystals are 3.2 - 3.4 kcal/mol. The energy of the TMTSF...C70 intermolecular interactions in the (TMTSF)X(C70)y(C6H6)z crystal are 3.0 - 3.5 kcal/mol.