Synthesis, crystal structure and thermal analysis of two transition metal coordination compounds based on flexible 2-nitro-benzene-1,4-dioxyacetic acid (NBDOA)

Two transition metal coordination compounds, [Cd(NBDOA) · (H ₂O)₂]_n and [Co(phen) · (H ₂O)₄](NBDOA) · 2H₂O, were synthesized and characterized by elemental analysis and infrared (IR) spectroscopy. The structures investigated by X-ray single crystal diffraction reveal that the coordination polymer [Cd(NBDOA) · (H₂O)₂] _n possesses two kinds of microporous channels which are bridged by five kinds of hydrogen bonds to generate a 3-D supramolecular network. [Co(phen)(H₂O)₄](NBDOA) · 2H₂O was constructed by [Co(phen) · (H₂O)₄]²⁺ and NBDOA^2- through electrostatic attraction and many kinds of hydrogen-bonding interactions. The thermal stabilities of the compounds were studied by differential scanning calorimeter (DSC) and thermogravimetry- differential thermogravimetric (TG-DTG) measurements, which shows that cadmium(II) and cobalt(II) complexes begin exothermic decomposition at 540 K and 529 K with final residues of CdO and CoO, respectively.