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

摘要

Electrocrystallization of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) in the presence of the tris(chloranilato)ferrate(III) [Fe- (Cl_2An)_3]~(3-) paramagnetic chiral anion in different stoichiometric ratios and solvent mixtures afforded three different hybrid systems formulated as [BEDT-TTF]_3[Fe(Cl_2An)_3]?3CH_2Cl_2?H_2O (1), δ-[BEDT-TTF]5[Fe- (Cl_2An)_3]?4H_2O (2), and α?-[BEDT-TTF]18[Fe(Cl_2An)_3]_3?3CH_2Cl_2? 6H_2O (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(Cl_2An)_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.