Crystalline patterns and band structure dimensionality in a series of conducting hybrids associating amide-functionalized EDT-TTF π-donors with the isosteric octahedral anions [FeNO(CN)5]2− and [M(CN)6]3− (M=Co, Fe)

Abstract : Four new radical cation salts based on the amide functionalized EDT-TTF organic donors EDT-TTF-CONH2 (D1) and EDT-TTF-(CONH2)2 (D2), α′-(D1)4[FeNO(CN)5] (1), α′-(D1)4[Co(CN)6] (2), β-(D1)6[Fe(CN)6] (3) and (D2)4[FeNO(CN)5]NB (4), have been synthesized and characterized by X-ray single crystal diffraction experiments, band structure calculations and electrical resistivity measurements. Functionalized organic donors are remarkable for the ability to form cation⋯cation and cation⋯anion type hydrogen bonds which can effectively direct the crystal architecture of molecular conductors. The structural analysis reveals a well-developed hydrogen bond network in the crystals investigated. (D1)2-dimers or (D2)n-extended zigzag chains of donors connected through functional groups are found to be stable structural motifs in 1–4. Remarkably, salts 1 and 2 are isostructural despite the presence of anions of different charge (−2 and −3, respectively) and the inherent difference in the degree of charge transfer has a clear effect on the transport properties: σRT(2)/σRT(1) = 300. Salt 3 differs from 1 and 2 both in the stoichiometry and packing of the conducting organic layer. Crystals of 4 exhibit a superstructure with the incommensurate vector q = ±(0.5, 0.3, 0.2).