Synthesis and Characterization of ReO 4 -Containing Microporous and Open Framework Structures
2004; American Chemical Society; Volume: 43; Issue: 18 Linguagem: Inglês
10.1021/ic049609h
ISSN1520-510X
AutoresJunhua Luo, Ben Alexander, Timothy R. Wagner, Paul A. Maggard,
Tópico(s)Polyoxometalates: Synthesis and Applications
ResumoA microporous and an open framework structure, [Cu2(pzc)2(H2O)2ReO4] (I) and [Cu(pzc)(H2O)ReO4]·2H2O (II) (pzc = 2-pyrazinecarboxylate), respectively, have been prepared using hydrothermal methods and characterized using IR, TGA, and X-ray diffraction (I Pnma, No. 62, Z = 4, a = 7.4949(9) Å, b = 24.975(3) Å, c = 9.141(1) Å; II P21/c, No. 14, Z = 4, a = 8.5878(9) Å, b = 12.920(1) Å, c = 9.741(1) Å, β = 92.830(2)°). I and II crystallize as red and blue solids, respectively, and each contains chains constructed from alternating Cu(pzc)2/ReO4 oxide-bridged metal sites. The bidentate pzc ligand further bridges each −Cu−O−Re−O− chain to adjacent chains, via the Cu sites, to form a 3D net in I, with ellipsoidal channels that are ∼3.3−4.7 Å × 12.5 Å, and in II, stacked layers of square nets with H2O-filled cavities that are ∼4.4 × 5.1 Å. Local ReO4- groups, a component of common oxidation catalysts, are directed at the channels and cavities of each structure, respectively. Thermogravimetric analysis indicates that I loses up to 64% of its H2O content before decomposition at 225 °C, while II loses ∼100% of its H2O content by 265 °C.
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