| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1337528 | Polyhedron | 2009 | 8 Pages |
The reaction of CaCO3 with 2-nitrobenzoic acid (2-nbaH) results in the formation of a coordination polymer, [Ca(2-nba)2(H2O)2]n (1) (2-nba = 2-nitrobenzoate), which can be dehydrated to [Ca(2-nba)2] (2). Compound 2 can be rehydrated to 1 on exposure to water vapor. Compounds 1 and 2 were characterized by elemental analysis, IR and UV–Vis spectra, and TG-DSC thermograms. Compound 1 crystallizes in the triclinic space group P1¯ and its structure consists of an eight coordinated calcium(II), two terminal aqua ligands and two crystallographically independent 2-nba anions, both of which function as μ2–η2:η1 bridging ligands. Each unique 2-nba ligand is linked to Ca(II) in a bidentate fashion via the carboxylate oxygen atoms and is further linked to a symmetry related Ca(II) via one of the oxygen atoms. A pair of such μ2–η2:η1 2-nba ligands are bridged to two symmetry related Ca(II) ions, resulting in the formation of a tricyclic dicalcium-bis(2-nitrobenzoate) moiety, which constitutes the basic building block of the polymer. In the crystal structure of 1, alternating pairs of bridging 2-nba ligands link pairs of {Ca(H2O)2}2+ units into a 1-D polymeric chain extending along the a-axis. The oxygen atoms of the coordinated water, and the carboxylate and nitro groups of 2-nba are involved in O–H···O and C–H···O interactions.
Graphical abstractA pair of μ2–η2:η1 carboxylate ligands bridge two symmetry related Ca(II) ions leading to the formation of a tricyclic dicalcium-bis(2-nitrobenzoate) unit which constitutes the building block of the coordination polymer.Figure optionsDownload full-size imageDownload as PowerPoint slide
