The syntheses and molecular structures of the two types of α-Dawson-type trialuminum-substituted polyoxometalates, [B-α-H3P2W15O59{Al(OH2)}3](6-) (1) and [B-α-H3P2W15O59{Al(OH)}2{Al(OH2)}]2(16-) (2), are described herein. The potassium and cesium salts of 1, K6[B-α-H3P2W15O59{Al(OH2)}3]·14H2O (K-1), and Cs6[B-α-H3P2W15O59{Al(OH2)}3]·13H2O (Cs-1) were formed by a stoichiometric reaction in water of trilacunary α-Dawson polyoxotungstate with aluminum nitrate under acidic conditions (pH ∼3). The potassium/sodium and tetramethylammonium/sodium salts of 2, K14Na2[B-α-H3P2W15O59{Al(OH)}2{Al(OH2)}]2·30H2O (KNa-2) and [(CH3)4N]14Na2[B-α-H3P2W15O59{Al(OH)}2{Al(OH2)}]2·39H2O (TMANa-2) were obtained under basic conditions (pH ∼9). These compounds were characterized by X-ray structure analyses, elemental analyses, thermogravimetric/differential thermal analyses, Fourier transform infrared, and solution (31)P, (27)Al, and (183)W NMR spectroscopy. The polyoxoanion 1 is a monomeric, α-Dawson-type structure, resulting in an overall C3v symmetry, while the polyoxoanion 2 is a hydrogen-bonded dimeric structure, resulting in an overall S3 symmetry in the solid state. The pH dependence of polyoxoanions 1 and 2 in aqueous solution was also investigated by (31)P NMR spectroscopy.

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The organozirconium complex with -Keggin-type mono-aluminum-substituted silicotungstate, [(n-C4H9)4N]6[-SiW11Al(OH)2O38ZrCp2]2•2H2O (TBA-Si-Al-Zr) was synthesized by the reaction of Cp2Zr(OTf)2THF (or Cp2ZrCl2) with [(n-C4H9)4N]4K0.5H0.5[-SiW11{Al(OH2)}O39]H2O in acetonitrile. This compound showed high catalytic activities for Meerwein-Ponndorf-Verley reduction of ketones with 2-propanol in both homogeneous and heterogeneous system.

The synthesis and molecular structure of a dimeric, mono-aluminum complex composed of two tri-lacunary α-Dawson polyoxometalates, [H14Al(B-α-P2W15O56)2]7− (1), is described herein. The tetra-n-butylammonium salt of 1, [(n-C4H9)4N]7[H14Al(B-α-P2W15O56)2] (TBA-1) was prepared by passing an aqueous solution of K6[B-α-H3P2W15O59{Al(OH2)}3]⋅14H2O through an ion-exchange resin column (H+-form), followed by addition of tetra-n-butylammonium bromide. Analytically pure and colorless crystals of TBA-1 were obtained via vapor diffusion from acetonitrile/methanol at ~25 °C. Single-crystal X-ray structure analysis revealed that a six-coordinate aluminum ion was sandwiched between two tri-lacunary α-Dawson-type units, resulting in an overall C2h symmetry. The characterization of TBA-1 was accomplished by elemental analyses, thermogravimetric/differential thermal analyses, Fourier-transform infrared spectroscopy, and solution 31P nuclear magnetic resonance spectroscopy. The photochromic properties of TBA-1 were also characterized in methanol under light irradiation (λ = 365 nm and ≥400 nm).

The monomeric -Dawson-type [B--H 3P2W15O59{Al(OH2)}3] 6polyoxoanion of (IV) having an overall C 3v symmetry is obtained under acidic conditions while a H-bonded dimeric [B--H 3P2W15O59{Al(OH)}2{Al(OH2 anion with an overall S3 symmetry is obtained under basic conditions. (VII) crystallizes in the monoclinic space group C2/c (Z = 8, single crystal XRD). -(KATO*, C. N.; KASHIWAGI, T.; UNNO, W.; NAKAGAWA, M.; UNO, H.; Inorg. Chem. 53 (2014) 10, 4824-4832, http://dx.doi.org/10.1021/ic402650g ; Dep. Chem., Fac. Sci., Shizuoka Univ., Suruga, Shizuoka 422, Japan; Eng.) -J. Schramke 30-020 )}] 16-2