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

A range of functionalised symmetrical and unsymmetrical tetrathiafulva lene (TTF) derivatives containing substituted 4,5-(propylenedithio)-1, 3-dithiole units has been prepared. Key half-units are the t-butyldiph enylsilyl-protected 1,3-dithiole derivative 18 and the ketal-protected derivative 32. Self-coupling and cross-coupling reactions of these ha lf-units, with 1,3-dithiole-2-one and -2-thione derivatives 19-22 occu rs in the presence of triethylphosphite. After deprotection, TTF deriv atives 14, 24, 28, 35 and 40-43, bearing hydroxy or ketone functionali ty are obtained. Functionalisation of the alcohol group(s) of 14, 24 a nd 28 has been achieved with acid chlorides and with isocyanates, to g ive compounds 16, 17, 25, 26 and 29. Cyclic voltammetric studies estab lish that the new TTF derivatives are efficient pi-electron donors; th ey undergo two reversible, single-electron redox waves. The X-ray crys tal structures of 5-(2-hydroxypropylenedithio)-1,3-dithiole-2-thione 3 and the ketal-protected TTF derivative 37 are described.