catena-Poly[[diaquamanganese(II)]-μ-7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylato]

In the title polymer, [Mn(C8H8O5)(H2O)2]n, the MnII atom is in a distorted octahedral coordination mode, binding to the bridging O atom of the bicycloheptane unit, two O atoms from corresponding carboxylate groups, one carboxylate O atom from a symmetry-related bridging ligand and two water O atoms. This arrangement leads to the formation of polymeric chains propagating parallel to [001]. The crystal structure is stabilized by several O—H⋯O hydrogen-bonding interactions involving the coordinated water molecules as donors and the carboxylate O atoms as acceptors.

In the title polymer, [Mn(C 8 H 8 O 5 )(H 2 O) 2 ] n , the Mn II atom is in a distorted octahedral coordination mode, binding to the bridging O atom of the bicycloheptane unit, two O atoms from corresponding carboxylate groups, one carboxylate O atom from a symmetry-related bridging ligand and two water O atoms. This arrangement leads to the formation of polymeric chains propagating parallel to [001]. The crystal structure is stabilized by several O-HÁ Á ÁO hydrogen-bonding interactions involving the coordinated water molecules as donors and the carboxylate O atoms as acceptors.
The crystal structure is stabilized by several hydrogen bonding interactions of the type O-H···O, involving the coordinated water molecules as donors and carboxylate O atoms as acceptors (Table 2).

Experimental
Disodium demethylcantharate was prepared in accordance with the literature technique (Yin et al., 2003).
A solution of manganese(II) acetate (1 mmol) and disodium demethylcantharate (1 mmol) was stirred at the room temperature. After 1 h, a solution of 2-amino-1,3,4-thiadiazole (2 mmol) was added dropwise to the mixed solution. Crystals suitable for single-crystal X-ray diffraction were obtained as colourless blocks over a period of several weeks.

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 Rfactors(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.