Unsymmetrical tetraheterofulvalenes (π-Donors) having at least one pyrazino-ring and a number of their charge transfer complexes and cation radical salts have been prepared and studied.

Some Nitrogen-Containing Tetraheterofulvalenes and a Few of Their Conductive Salts

Thermal properties of tetrakis(alkyltelluro)tetrathiafulvalenes (TTeCn-TTF) are investigated using DSC technique. It is shown that combining tellurium substituted TTF skeleton with the alkyl chains of different length we got a variety of thermal properties due to a competition between the alkyl chains and the TTF moiety. This competition leads to a polymorphism and to an irregular dependence of the melting point as well as enthalpy and entropy of melting on the alkyl chain length between the carbon number n = 4 and 7. For the compounds with long alkyl chains (n > 6) the analysis of thermodynamic properties confirms the existence of the molecular fastener effect, i.e. fastening of the TTF skeletons and decreasing of the distances between them in the crystal structure by crystallization of the long alkyl chains.

H. Inokuchi

Papers

A new type of organic semiconductors: molecular fastener