Synthesis and characterization of ReO4-containing microporous and open framework structures

A microporous and an open framework structure, [Cu-2(pzc)(2)(H2O)(2)ReO4] (1) and [Cu(pzc)(H2O)ReO4].2H(2)O (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(g) Angstrom, b = 24.975(3) Angstrom, c = 9.141 (1) Angstrom; II P2(1)/c, No. 14, Z = 4, a = 8.5878(9) Angstrom, b = 12.920(1) Angstrom, c = 9.741 (1) Angstrom, beta = 92.830(2)degrees). 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 similar to3.3-4.7 Angstrom x 12.5 Angstrom, and in II, stacked layers of square nets with H2O-filled cavities that are similar to4.4 x 5.1 Angstrom. 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 degreesC, while II loses similar to100% of its H2O content by 265 degreesC.