The synthesis, redox properties and X-ray crystal structures of two new tetrathiafulvalene-thiophene donors

The functionalisation of tetrathiafulvalene with thiophene units is reported via the synthesis of two multiredox compounds 4 and 5. The two molecules represent a fused structure (4) and a TTF-thiophene system directly linked by a single bond (5); both compounds are endowed with 'free' 2,5-positions within the thiophene ring, making them accessible to polymerisation reactions. The solution electrochemistry of 4 and 5 reveals the redox properties of the two components: a three-stage oxidation process is seen in each case. Charge-transfer complexes have been prepared, using TCNQ or TCNQF(4) as the electron acceptor, with conductivities in the range of 10(-4) to 0.22 S cm(-1). Compounds 4 and 5 have been studied by X-ray crystallography; the former exhibits kappa-packing whilst the latter shows a high degree of conjugation between the two donor moieties