Coordination frameworks assembled from CuII 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^II₂(1,3-bdpb)(OCH₃)₂] (CFA-5) and [Cu^ICl(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 R (no. 148) and the unit cell parameters are as follows: a = 26.839(3), c = 15.8317(16) Å, V = 9876.2(19) ų. 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^ICl(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) ų. 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.