Bis(2-aminobenzothiazol-3-ium) bis(7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylato-κ3 O 2,O 3,O 7)zincate hexahydrate

In the title hydrated molecular salt, (C7H7N2S)2[Zn(C8H8O5)2]·6H2O, which is isotypic with its MnII, CoII and NiII analogues, the Zn2+ ion lies on a crystallographic inversion centre and a distorted ZnO6 octahedral coordination geometry arises from the two doubly deprotonated O,O′,O′′-tridentate ligands. In the crystal, the components are linked by N—H⋯Oa, N—H⋯Ow, Ow—H⋯Oa and Ow—H⋯Ow hydrogen bonds (w = water and a = anion).

In the title hydrated molecular salt, (C 7 H 7 N 2 S) 2 -[Zn (C 8 H 8 O 5 ) 2 ]Á6H 2 O, which is isotypic with its Mn II , Co II and Ni II analogues, the Zn 2+ ion lies on a crystallographic inversion centre and a distorted ZnO 6 octahedral coordination geometry arises from the two doubly deprotonated O,O 0 ,O 00tridentate ligands. In the crystal, the components are linked by N-HÁ Á ÁO a , N-HÁ Á ÁO w , O w -HÁ Á ÁO a and O w -HÁ Á ÁO w hydrogen bonds (w = water and a = anion).

Experimental
A mixture of 0.5 mmol norcantharidin, 0.5 mmol zinc acetate, 0.5 mmol 2-aminobenzothiazole and 15 mL distilled water was sealed in a 25 mL Teflon-lined stainless vessel and heated at 443 K for 3 d, then cooled slowly to room temperature.
The solution was filtered and colourless blocks were recovered.

Refinement
H atoms bonded to C atoms were positioned geometrically and refined using a riding model [aliphatic of tertiary carbon C-H = 0.98 Å, aliphatic of secondary carbon C-H = 0.97 Å, N-H = 0.86 Å, both with U iso (H) = 1.2U eq (C)]. The H atoms bonded to O atoms were located in a difference Fourier maps and refined with O-H distance restraints of 0.85 (4) Å and U iso (H) = 1.5U eq (O).  A view of (I) showing displacement ellipsoids drawn at the 30% probability level. Atoms with label suffix A are generatd by (1-x, -y, -z).

Bis(2-aminobenzothiazol-3-ium) bis(7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylato-κ 3 O 2 ,O 3 ,O 7 )zincate hexahydrate
Crystal data Hall symbol: -P 1 a = 6.6983 (7) Å b = 10.1497 (11) Å c = 13.2082 (14) Å α = 90.172 (7)  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.48 e Å −3 Δρ min = −0.74 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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.