A two-dimensional strong hydrogen-bond network constructed from a transition metal with a polycarboxylato ligand

The supramolecular complex with mixed-ligands [Co₂(1,2,4,5-btec) (2,2′-bipy)₂(H₂O)₆]·2H ₂O (1,2,4,5-btec = benzene-1,2,4,5-tetracarboxylic acid; 2,2′-bipy = 2,2′-bipyridine) was prepared and characterized by elemental analyses, IR spectra and X-ray single-crystal diffraction analysis. X-ray crystal structural analysis reveals that the compound belongs to the monoclinic system. C₃₀H₃₄Co₂N₄O ₁₆, P2₁/n, a = 12.2998(5) Å, b = 7.5943(3) Å, c = 17.9100(5) Å, α = 90.00°, β = 100.0790(3)°, γ = 90.00°, V = 1647.13(10) ų, Z = 2. The complex is dinuclear with two Co atoms linked by two O atoms from one 1,2,4,5- benzenetetracarboxylate. In the unit of the structure, the two bipys are in same plane, and the dihedral angle with the benzene ring is 64.1°. There exist strong hydrogen bonds between the carboxylate oxygen atoms and coordinated water in the plane and weak H-bonding between the carboxylate oxygen atoms and H-C in the aromatic ring perpendicular to the plane.