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    • Keywords


      Coordination polymer; catena-poly[[hexa(aqua)dibarium(II)]bis[($\mu_2$-2-nitrobenzoato-O,O,ONO2)($\mu_2$-2-nitrobenzoato-O,O,O')]]; nitro ligation; tridentate; monoatomic bridge; nine coordination.

    • Abstract


      The aqueous reaction of barium carbonate with 2-nitrobenzoic acid (2-nbaH) results in the formation of a one-dimensional coordination polymer, catena-poly[[hexa(aqua)dibarium(II)]bis[($\mu_2$-2-nitrobenzoate-O,O,O-NO2)($\mu_2$-2-nitrobenzoate-O,O,O')]] 1. On heating at 100°C compound 1 is dehydrated to anhydrous barium bis(2-nitrobenzoate) 2. The anhydrous compound can be re-hydrated to 1 on exposure to water vapour. Compounds 1 and 2 were characterized by elemental analysis, IR and UV-Vis spectra, DSC thermograms, weight loss studies and the structure of 1 was determined. 1 and 2 can be thermally decomposed to BaCO3 by heating at 800°C. The polymer [[Ba(H2O)3]2($\mu_2$-2-nba-O,O,O-NO2)2 ($\mu_2$-2-nba-O,O,O')2]$_n$ 1 crystallizes in the centrosymmetric triclinic space group P$_{\bar{i}}$ and all atoms are located in general positions. The polymeric structure is based on a dimeric unit and consists of three water molecules coordinated to a central Ba(II) and two unique 2-nitrobenzoate (2-nba) anions, one of which ($\mu_2$-2-nba-O,O,O-NO2) functions as a tridentate ligand and is linked to a Ba(II) through the oxygen atom of the -NO2 group and forms a monoatomic $\mu_2$-carboxylate bridge between two symmetry related Ba(II) ions with a Ba$\cdots$Ba distance of 4.5726(14) Å. The second unique 2-nba anion ($\mu_2$-2-nba-O,O,O') also functions as a tridentate ligand with the carboxylate oxygen atoms linked to a Ba(II) ion in a bidentate fashion and one of the carboxylate oxygen atoms forming a monoatomic bridge between two symmetry related Ba(II) ions resulting in a Ba$\cdots$Ba separation of 4.5406(15) Å. These differing tridentate 2-nba ligands link {Ba(H2O)3} units into a one-dimensional polymeric chain extending along 𝑏 axis. In the infinite chain each nine coordinated Ba(II) is bonded to three water molecules and further linked to six oxygen atoms of four different 2-nitrobenzoate anions with alternating pairs of Ba(II) ions in the chain bridged by a pair of ($\mu_2$-2-nba-O,O,O-NO2) and ($\mu_2$-2-nba-O,O,O') ligands resulting in alternating Ba$\cdots$Ba distances of 4.5406(15) and 4.5726(14) Å across the chain.

    • Author Affiliations


      Bikshandarkoil R Srinivasan1 Santosh Y Shetgaonkar1 Pallepogu Raghavaiah1 2

      1. Department of Chemistry, Goa University, Goa 403 206
      2. School of Chemistry, University of Hyderabad, Hyderabad 500 046
    • Dates

  • Journal of Chemical Sciences | News

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