Coordination frameworks assembled from Cu(II) ions and H₂-1,3-bdpb ligands: X-ray and magneto structural investigations, and catalytic activity in the aerobic oxidation of tetralin.

Abstract

The syntheses and crystal structures of H2-1,3-bdpb·MeOH, [Cu(II)2(1,3-bdpb)(OCH3)2] (CFA-5) and [Cu(I)Cl(H2-1,3-bdpb)] (H2-1,3-bdpb = 1,3-bis(3,5-dimethyl-1H-pyrazol-4-yl)benzene) are described. The copper(II) containing metal-organic framework (termed Coordination Framework Augsburg University-5, CFA-5) crystallizes in the trigonal crystal system, within the space group R3̄ (no. 148) and the unit cell parameters are as follows: a = 26.839(3), c = 15.8317(16) Å, V = 9876.2(19) Å(3). CFA-5 features a two-fold interpenetrated 3-D microporous framework structure of cross-linked wheel-shaped {Cu(II)(pz)(OMe)}12 fundamental building units, each containing twelve copper(II) ions, μ2-bridging MeO(-) groups and pyrazolate (pz(-)) ligands. Replacing copper(II) acetate by copper(II) chloride in the synthesis leads to compound [Cu(I)Cl(H2-1,3-bdpb)], which crystallizes in the orthorhombic crystal system, within the space group Pnma (no. 62) and the unit cell parameters are as follows: a = 6.1784(8), b = 6.1784(8), c = 6.1784(8) Å, V = 1583.8(4) Å(3). In contrast to the former compound, CuCl(H2-1,3-bdpb) is a non-porous compound consisting of Cu(I)-Cl zigzag chains expanding in the direction [100] and H2-1,3-bdpb ligands. CFA-5 is characterized by elemental and thermogravimetric analyses, variable temperature powder X-ray diffraction and IR-spectroscopy; and its porosity and magnetic properties are described in detail. CFA-5 shows a promising catalytic activity in the heterogeneously catalyzed aerobic oxidation of tetralin, which is compared with other catalytically active metal-organic frameworks.