A novel diphosphoheptadecatungstate complex, [(P2O7)W17O51]4− was prepared from a 200 mM (M = mol dm−3) W(VI)–10 mM P2O74−–0.6 M HCl–40% (v/v) CH3CN system, and characterized by IR, UV–vis, 31P NMR, and 183W NMR spectroscopy, and voltammetry. Single-crystal X-ray analysis was made on [(C2H5)4N]4[(P2O7)W17O51]·CH3CN, which crystallized in the monoclinic space group P21/n, with cell parameters a = 16.1877(8), b = 22.103(1), c = 22.670(1) Å, β = 90.847(1)°, V = 8110.3(7) Å3, and Z = 4. The anion consists of a PW8O31 fragment derived from a β-Keggin-type [PW12O40]3− structure, and two PW8O31 units are linked by five oxygen atoms and a WO5 square pyramid. The [(P2O7)W17O51]4− anion exhibited a four-step reversible one-electron redox wave in CH3CN, and a three-step two-electron redox wave resulted in the presence of acid. This is the first example of an electrochemically-active diphosphotungstate complex.
Tungsten I 5700 Preparation, Structure, and Characterization of a Novel Diphosphoheptadecatungstate Complex, [(P2O7)W17O51] 4-. -(Bu4N)4[(P2O7)W17O51] (I) is synthesized from Na2WO4, Na4P2O7, and Bu4NBr (HCl, H2O/MeCN, 25°C, yield given in g) and characterized by IR, UV/VIS, 31 P, and 183 W NMR spectroscopy and by cyclic voltammetry. Crystals of (Et4N)4[(P2O7)W17O51]·MeCN (II) suitable for single crystal XRD analysis are prepared by addition of Et 4 NClO 4 to a solution of (I) in MeCN. (II) crystallizes in the monoclinic space group P21/n with Z = 4. The anion of (II) consists of two PW8O31 units which are linked by five oxygen atoms and a WO5 square pyramid. The title anion is the first example of an electrochemically active diphosphotungstate complex. -(HIMENO*, S.; KATSUTA, T.; TAKAMOTO, M.; HASHIMOTO, M.; Bull. Chem.
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