Halogenated tetrathiafulvalenes (TTFs): Preparation, X-ray structure and cyclic voltammetry of tetrachloro-,2,3-dichloro-6,7-dimethyl- and 2,3-diiodo-6,7-dimethyl-TTF

Lithiation of tetrathiafulvalene (TTF) with butyllithium in tetrahydrofuran (THF) followed by quenching with hexachloroethane (HCE), 1,2-dibromotetrachloroethane (BCE) or 1,2-dibromotetrafluoroethane (BFE) affords improved yields of both tetrabromo-TTF (Br₄TTF) and tetrachloro-TTF (Cl₄TTF), compared to earlier reports. By a similar procedure, 2,3-dimethyl-TTF (2,3-Me₂TTF) undergoes lithiation followed by chlorination with HCE, bromination with BCE or BFE and iodination with perfluorohexyl iodide (PFHI), affording 2,3-dichloro-6,7-dimethyl-TTF (Cl₂Me₂TTF), 2,3-dibromo-6,7-dimethyl-TTF (Br₂Me₂TTF) and 2,3-diiodo-6,7-dimethyl-TTF (l₂Me₂TTF), respectively. The single-crystal structures of Cl₄TTF, Cl₂Me₂TTF and l₂Me₂TTF have been determined. Halogen substitution on the TTF skeleton leads to a variety of packing features in the crystal structures of the resulting compounds.