Spontaneous Redox Synthesis of the Charge Transfer Material TTF₄[SVMo₁₁O₄₀]

The charge-transfer material TTF-SV^IVMo₁₁O₄₀ (TTF = tetrathiafulvalene) was prepared by a spontaneous redox reaction between TTF and the vanadium-substituted polyoxometalate (n-Bu₄N)₃[SV^VMo₁₁O₄₀] in both solution and solid state phases. Single crystal X-ray diffraction gave the stoichiometry TTF₄[SVMo₁₁O₄₀]·2H₂O·2CH₂Cl₂, with the single V atom positionally disordered with eight Mo atoms over the whole α-Keggin polyanion [SVMo₁₁O₄₀]^4‑. Raman spectra support the 1+ charge assigned to the oxidized TTF deduced from bond lengths, and elemental and voltammetric analysis also are consistent with this formulation. Scanning electron microscopy images showed a rod-type morphology for the new charge-transfer material. The conductivity of the solid at room temperature is in the semiconducting range. The TTF and (n-Bu₄N)₃[SV^VMo₁₁O₄₀] solids also undergo a rapid interfacial reaction, as is the case with TTF and TCNQ (TCNQ = tetracyanoquinodimethane) solids. EPR spectra at temperatures down to 2.6 K confirm the presence of two paramagnetic species, V­(IV) and the oxidized TTF radical. Spectral evidence shows that the TTF-SV^IVMo₁₁O₄₀ materials prepared from either solution or solid state reactions are equivalent. The newly isolated TTF-SV^IVMo₁₁O₄₀ material represents a new class of TTF-polyoxometalate compound having dual electrical and magnetic functionality derived from both the cationic and anionic components.