New complexes of fullerenes C60 and C70 with organic donor DBTTF: synthesis, some properties and crystal structure of DBTTF·C60·C6H6 (DBTTF=dibenzotetrathiafulvalene)

New complexes of fullerenes C60 and C70 with dibenzotetrathiafulvalene (DBTTF), DBTTF·C60·C6H6, DBTTF·C60·Py and DBTTF·C70·C6H6, were obtained. The crystal structure of DBTTF·C60·C6H6 was determined. The arrangement of fullerene molecules is approximately simple cubic packing where each C60 molecule is located in slightly distorted octahedral surrounding. DBTTF molecules have a concave conformation. X-ray photoelectron spectroscopy (XPS) and IR spectroscopy show only weak charge transfer in these compounds. A weak charge transfer band near 900 nm was found in the UV-Vis-NIR absorption spectrum of DBTTF·C60·C6H6 single crystals. DBTTF molecules are coordinated on C60 ones by π-π and n-π interactions. It was shown that the steric discrepancy between DBTTF and C60 molecules does not provide favourable conditions for charge transfer in the DBTTF·C60·C6H6 complex.