Received 19 June 2013
The title compound, [Co(C5H3N2O2)2(H2O)2]·2H2O, contains a CoII ion on an inversion center, exhibiting an octahedral coordination geometry. The equatorial plane is formed by two trans-related N,O-bidentate pyridazine-3-carboxylate ligands and the axial positions are occupied by two water molecules. The CoII complex molecules are stacked in a column along the a-axis direction by an O-HN hydrogen bond between the non-coordinating pyridazine N atom and the coordinating water molecule. These columns are further connected into a layer parallel to the ac plane by additional hydrogen bonds involving the coordinating and non-coordinating water molecules, and the non-coordinating carboxylate O atom. The crystal packing is completed by interlayer weak C-HO interactions.
For the isotypic zinc(II) and manganese(II) complexes, see: Gryz et al. (2003); Ardiwlnata et al. (1989). For a related zinc(II) complex which does not contain non-coordinating water molecules, see: Gryz et al. (2004).
Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: OLEX2 (Dolomanov et al., 2009); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: WinGX (Farrugia, 2012) and PLATON (Spek, 2009).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: IS5284 ).
This work has been supported financially by Eusko Jaurlaritza/Gobierno Vasco (grants IT477-10 and S-PE11UN062) and the Universidad de País Vasco UPV/EHU (UFI11/53). BA thanks EJ/GV for his predoctoral fellowship.
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