FUNCTIONALIZED TETRATHIAFULVALENE (TTF) SYSTEMS DERIVED FROM 4,5-(PROPYLENEDITHIO)-1,3-DITHIOLE UNITS

A range of functionalised symmetrical and unsymmetrical tetrathiafulvalene (TTF) derivatives containing substituted 4,5-(propylenedithio)-1,3-dithiole units has been prepared. Key half-units are the t-butyldiphenylsilyl-protected 1,3-dithiole derivative 18 and the ketal-protected derivative 32. Self-coupling and cross-coupling reactions of these half-units, with 1,3-dithiole-2-one and -2-thione derivatives 19-22 occurs in the presence of triethylphosphite. After deprotection, TTF derivatives 14, 24, 28, 35 and 40-43, bearing hydroxy or ketone functionality are obtained. Functionalisation of the alcohol group(s) of 14, 24 and 28 has been achieved with acid chlorides and with isocyanates, to give compounds 16, 17, 25, 26 and 29. Cyclic voltammetric studies establish that the new TTF derivatives are efficient pi-electron donors; they undergo two reversible, single-electron redox waves. The X-ray crystal structures of 4,5-(2-hydroxypropylenedithio)-1,3-dithiole-2-thione 3 and the ketal-protected TTF derivative 37 are described.