Synthesis and Characterization of ReO4-Containing Microporous and Open Framework Structures.

A microporous and an open framework structure, [Cu2(pzc)2(H2O)2ReO4] (I) and [Cu(pzc)(H2O)ReO4]·2H20 (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) Åβ = 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. [ABSTRACT FROM AUTHOR]