DIOXO-OXOPYRIMIDOTETRATHIAFULVALENE AND AMINOOXOPYRIMIDOTETRATHIAFULVALENE - PI-ELECTRON DONORS FOR DESIGN OF CONDUCTING MATERIALS CONTAINING INTRAMOLECULAR HYDROGEN-BONDS OF NUCLEIC-ACID BASE-PAIR TYPE

Dimethyl[2,4-dioxo (1H,3H)pyrimido]tetrathiafulvalene (1) and thyl-[2- amino-4-oxo(3H)pyrimido]tetrathiafulvalene (4) form unusual inner salt s by oxidation in the presence of bases, The insoluble black-green bet aines 2 and 5 react with acids to form cation radical salts. Betaine 2 in the presence of acid and bis-(ethylenedithio)tetrathiafulvalene fo rms the unexpected double salt 8. In order to synthesise the cation ra dical salts of 1 and 4, it is necessary to use the ultrasonic method o wing to the insolubility of the starting compounds. Electrical measure ments of the betaines and cation radical salts in pressed samples show an unexpectedly low resistivity with semiconducting character: for be taine 2 rho(RT) = 840 Omega cm, for betaine 5 rho(RT) = 10 Omega cm, f or salt 7 rho(RT) = 40 Omega cm, but for double salt 8 rho(RT) = 50 Om ega cm. In the case of salt 8, very low values of activation energy of electrical conductivity of the order of kT were observed. The synthes is and purification of tetrathiafulvalene 4 from o-7-oxo-(6H)-1,3-dith iolo[4,5-d]pyrimidineselone-2 are described. (C) 1997 by John Wiley & Sons, Ltd.