Heteroatom Bridged Tetrathiafulvalenes

Tetrathiafulvalene (TTF) derivatives are the most representative electroactive precursors for the preparation of crystalline conducting materials. The occurrence of mixed valence states, through electron delocalization, as well as strong intermolecular interactions, are important prerequisites to account for the high electronic conduction in the solid state and the dimensionality of the material. In this respect, the modulation of through space or through bond intramolecular electron communication can be efficiently achieved in heteroatom bridged bis(TTF) derivatives. Moreover, the bridging heteroatoms can engage, depending on their nature, in intermolecular interactions in the solid state. In this Minireview, we focus on flexible and rigid bis(TTF) derivatives formulated as X(TTF)(2) and X-2(TTF)(2) (X = Si, Ge, Sn, P, Sb, S, Se, Te) thus containing one or two bridges in ortho position. A special attention is given to the solid-state structures of these precursors and their oxidized species, their electrochemical behavior, reactivity, role of the heteroatom in the establishment of intramolecular mixed valence and intermolecular interactions, and the conducting properties.