SYNTHESIS, PROPERTIES AND RADICAL-CATION SALTS OF NON-CENTROSYMMETRICAL TETRATHIAFULVALENES DERIVED FROM 1,3,5,7-TETRATHIA-S-INDACENE

1,3,5,7-Tetrathia-s-indacene, obtained by reduction of the correspondi ng bis(trithiocarbonate) with diisobutylaluminium hydride, is oxidized to the monodithiolium salt with Ph3C+PF6- to afford, after reaction w ith trimethyl phosphite, the corresponding 6H-1,3,5,7-tetrathia-s-inda cen-2-ylphosphonic acid dimethyl ester. This, in turn, reacts with a v ariety of 1,3-dithiol-2-yliminium salts to afford non-centrosymmetrica lly substituted tetrathiafulvalenes, the electrochemical properties of which are also reported. Electrocrystallization experiments led to th e formation of various semi-conducting radical cation salts. ,3-dithio l-2-ylidene)-1,3,5,7-tetrathia-s-indacene (1a) forms a salt with AsF6- , (1a)2AsF6, which crystallizes in the triclinic system, space group P - 1, with a = 7.246(6) b = 7.797(1), c = 15.041(2) angstrom, alpha = 100.73(1), beta = 91.44(3), gamma = 101.20(3)-degrees, V = 817.4 angst rom3. The donor molecules stack in a zig-zag fashion along the a axis.