Structural Diversity and Physical Properties of Paramagnetic Molecular Conductors Based on Bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) and the Tris(chloranilato)ferrate(III) Complex

• Published in: Inorganic chemistry 2014-07, Vol.53 (13), p.7028-7039
• Main Authors: Atzori, Matteo, Pop, Flavia, Auban-Senzier, Pascale, Gómez-García, Carlos J, Canadell, Enric, Artizzu, Flavia, Serpe, Angela, Deplano, Paola, Avarvari, Narcis, Mercuri, Maria Laura
• Format: Article
• Language: English
• Subjects: Chemical Sciences
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic501001r

Electrocrystallization of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) in the presence of the tris(chloranilato)ferrate(III) [Fe(Cl2An)3]3– paramagnetic chiral anion in different stoichiometric ratios and solvent mixtures afforded three different hybrid systems formulated as [BEDT-TTF]3[Fe(Cl2An)3]·3CH2Cl2·H2O (1), δ-[BEDT-TTF]5[Fe(Cl2An)3]·4H2O (2), and α‴-[BEDT-TTF]18[Fe(Cl2An)3]3·3CH2Cl2·6H2O (3). Compound 1 presents an unusual structure without the typical alternating organic and inorganic layers, whereas compounds 2 and 3 show a segregated organic–inorganic crystal structure where layers formed by Λ and Δ enantiomers of the paramagnetic complex, together with dicationic BEDT-TTF dimers, alternate with layers where the donor molecules are arranged in the δ (2) and α‴ (3) packing motifs. Compound 1 behaves as a semiconductor with a much lower conductivity due to the not-layered structure and strong dimerization between the fully oxidized donors, whereas 2 and 3 show semiconducting behaviors with high room-temperature conductivities of ca. 2 S cm–1 and 8 S cm–1, respectively. The magnetic properties are dominated by the paramagnetic S = 5/2 [Fe(Cl2An)3]3– anions whose high-spin character is confirmed by electron paramagnetic resonance and magnetic susceptibility measurements. The correlation between crystal structure and conductivity behavior was studied by means of tight-binding band structure calculations, which support the observed conducting properties.