Diaquabis(tetrazolo[1,5-a]pyridine-8-carboxylato-κ2 N 1,O)manganese(II) dihydrate

In the title compound, [Mn(C6H3N4O2)2(H2O)2]·2H2O, the MnII atom is located on a twofold rotation axis and is octahedrally coordinated by the N and O atoms of the chelating tetrazolo[1,5-a]pyridine-8-carboxylate anions and the O atoms of two water molecules. Hydrogen bonds of the O—H⋯O and O—H⋯N types lead to the formation of layers parallel to (100).

In the title compound, [Mn(C 6 H 3 N 4 O 2 ) 2 (H 2 O) 2 ]Á2H 2 O, the Mn II atom is located on a twofold rotation axis and is octahedrally coordinated by the N and O atoms of the chelating tetrazolo[1,5-a]pyridine-8-carboxylate anions and the O atoms of two water molecules. Hydrogen bonds of the O-HÁ Á ÁO and O-HÁ Á ÁN types lead to the formation of layers parallel to (100).
In the title compound, the manganese atom is located on a two fold axis and octahedrally coordinated by two water molecules and two bidentate N,O tetrazolo(1,5-a)pyridine-8-carboxylate, (Fig. 1).
Each tetrazolo(1,5-a) pyridine-8-carboxylate chelates to one manganese atom. One type of water coordinates to the manganese atom whereas the other acts as lattice water. A two dimensional supramolecular network parallel to the (1 0 0) plane, is formed by the hydrogen bond interactions between the water molecules and the nitrogen of the tetrazolo(1,5a)pyridine-8-carboxylate ligands (Table 1, Fig. 2).
The structure is closely related to the dihydrate complex (Xue & Liu, 2009), the only difference being the occurence of two solvate water molecules in the previous structure.

S2. Experimental
A mixture of manganeset(II)nitrate and sodium azide (1 mmol), 2-chloronicotinic acid(0.5 mmol), in 10 ml of water was sealed in a Teflon-lined stainless-steel Parr bomb that was heated at 363 K for 48 h. Red crystals of the title complex were collected after the bomb was allowed to cool to room temperature.Yield 20% based on manganese(II). Caution: Azides may be explosive. Although we have met no problems in this work, only a small amount of them should be prepared and handled with great caution.

S3. Refinement
All H atoms attached to C atoms were fixed geometrically and treated as riding with C-H = 0.93 Å and U iso (H) = 1.2U eq (C). H atoms of water molecule were located in difference Fourier maps and included in the subsequent refinement using restraints (O-H= 0.85 (1)Å and H···H= 1.39 (2)Å) with U iso (H) = 1.5U eq (O). In the last stage of refinement they were treated as riding on their parent O atoms.   Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.