Crystal structure of a novel one-dimensional zigzag chain-like cobalt(II) coordination polymer constructed from 4,4′-bipyridine and 2-hydroxybenzoate ligands

A novel one-dimensional zigzag chain-like CoII coordination polymer constructed from 4,4′-bipyridine (4,4′-bpy) and 2-hydroxybenzoate (2-OHbenz) ligands, namely, catena-poly[[(4,4′-bipyridine-κN)(μ-2-hydroxybenzoato-κ2O:O′)(2-hydroxybenzoato-κ2O,O′)cobalt(II)]-μ-4,4′-bipyridine-κ2N:N′-[aquahemi(μ-4,4′-bipyridine-κ2N:N′)(2-hydroxybenzoato-κO(2-hydroxybenzoato-κ2O:O′)cobalt(II)], [Co2(C7H5O3)4(C10H8N2)2.5(H2O)]n, has been synthesized by reacting cobalt(II) nitrate trihydrate, 4,4′-bpy and 2-hydroxybenzoic acid in a mixture of water and methanol at room temperature. There are two independent CoII centers, Co1 and Co2, in the asymmetric unit, revealing a distorted octahedral geometry with chromophore types of [CoN2O4] and [CoN2O3O′], respectively. The Co1 ions are doubly bridged by 2-OHbenz ligands with syn–anti coordination mode, generating a dinuclear unit. The bridging 4,4′-bpy ligands connect these dinuclear units and the mononuclear Co2 chromophores, providing a one-dimensional alternating zigzag chain-like structure. In the crystal, intermolecular hydrogen bonds, C—H...π and π–π stacking interactions are observed and these help to consolidate the packing. In addition, the physical properties of the title compound are reported.