Spontaneous Redox Synthesis and Characterization of the Tetrathiafulvalene鈥揤anadium-Substituted Polyoxometalate Charge-Transfer Material TTF4[SVW11O40]: Comparison wit

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• 作者：Qi Li ; Jinzhen Lu ; John F. Boas ; Daouda A. K. Traore ; Matthew C. J. Wilce ; Lisandra L. Martin ; Tadaharu Ueda ; Alan M. Bond
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：October 20, 2014
• 年：2014
• 卷：53
• 期：20
• 页码：10996-11006
• 全文大小：565K
• ISSN：1520-510X

文摘

Both conventional solution-phase and direct solid鈥搒olid redox reactions between tetrathiafulvalene (TTF) and the vanadium-substituted polyoxometalate (n-Bu₄N)₃[SV^VW₁₁O₄₀] give rise to microcrystalline or powdered semiconducting charge transfer solid material. A single-crystal X-ray structure derived from growing crystals from a MeCN鈥揅H₂Cl₂ solution-phase redox reaction gives a stoichiometry of TTF₄[SVW₁₁O₄₀]路2H₂O路2CH₂Cl₂ and reveals that there are two crystallographically different TTF cation moieties based on (TTF₂)²⁺ dimers. While the color and morphology of the microcrystalline or powdered TTF₄[SVW₁₁O₄₀] differ from the single crystals prepared for structural analysis, all materials are spectroscopically (infrared (IR), Raman with respect to the TTF bands, and electron paramagnetic resonance (EPR)) indistinguishable. Raman spectra suggest that the charge transfer is unevenly distributed across the (TTF₂)²⁺ dimers, which is postulated to give rise to enhanced mixed-valence features. Structural, spectral, and other properties, such as conductivity, are compared with results available on the recently published molybdenum TTF₄[SVMo₁₁O₄₀]路2H₂O路2CH₂Cl₂ analogue, where the charge distribution is uniform on all TTF cations. In both examples, the position of the V atom is located over several sites. Elemental analysis and voltammetric data also are consistent with the formulations deduced from structural and spectroscopic studies. The conductivity at room temperature is in the semiconducting range, but significantly greater than that for the Mo analogue. EPR spectra at temperatures down to the liquid helium regime confirm the presence of paramagnetic V(IV) and paramagnetic oxidized TTF. The newly isolated TTF-SV^IVW₁₁O₄₀ material also has magnetic functionality derived from the cationic and anionic components.