Charge Transfer Salt with Substituted Lindquist Polyoxometalate: Synthesis, Crystal Structure, and Physical Properties of α-(BEDT-TTF)₆(VW₅O₁₉)⋅DMF⋅2H₂O

Abstract

A new charge transfer salt based on bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) and the vanadium substituted Lindquist anion [VW₅O₁₉]³⁻ was synthesized and characterized by X-ray and spectroscopic analysis. Monoclinic, C2, F _w =3789.2, a=41.5019(5), b=11.2600(2), c=12.7514(2) Å, β=101.877(5)°, Z=2, R=0.060, based on 12095 reflections with I>2σ(I). The structure consists of alternating organic and inorganic layers. The inorganic layer is generated by [VW₅O₁₉]³⁻ anions, dimethylformamide (DMF) and water molecules. The organic layer, which is generated by three different BEDT-TTF units, belongs to the α-type of packing and consists of trimerized chains parallel to the c direction. The compound is a semi-conductor with σ _{300 K} =1.1 S⋅cm⁻¹ and E _a =0.1 eV. Polarized reflectance spectra of single crystals were measured over the spectral range from 650 to 25000 cm⁻¹. FT-NIR Raman spectra of powdered crystals dispersed in KBr pellets were also recorded. Vibrational and electronic features are discussed.