| Crystal data | 
| Chemical formula | [Ba(C3H2N3O2)2(H2O)2]·H2O | 
| M
r | 415.54 | 
| Crystal system, space group | Orthorhombic, Pmn21 | 
| Temperature (K) | 173 | 
| a, b, c (Å) | 13.6667 (17), 4.4102 (7), 11.2816 (14) | 
| V (Å3) | 679.97 (16) | 
| Z | 2 | 
| Radiation type | Mo Kα | 
| μ (mm−1) | 2.96 | 
| Crystal size (mm) | 0.22 × 0.18 × 0.15 | 
|  | 
| Data collection | 
| Diffractometer | Stoe Image plate diffraction system-2T | 
| Absorption correction | Numerical [X-RED (Stoe & Cie, 2001 ▸) and X-SHAPE (Stoe & Cie, 1999 ▸)] | 
| Tmin, Tmax | 0.310, 0.399 | 
| No. of measured, independent and observed [I > 2σ(I)] reflections | 3251, 1696, 1688 | 
| R
int | 0.016 | 
| (sin θ/λ)max (Å−1) | 0.692 | 
|  | 
| Refinement | 
| R[F2 > 2σ(F2)], wR(F2), S | 0.017, 0.043, 1.15 | 
| No. of reflections | 1696 | 
| No. of parameters | 119 | 
| No. of restraints | 13 | 
| H-atom treatment | All H-atom parameters refined | 
| Δρmax, Δρmin (e Å−3) | 0.72, −1.87 | 
| Absolute structure | Flack x determined using 668 quotients [(I+)−(I−)]/[(I+)+(I−)] (Parsons et al., 2013 ▸) | 
| Absolute structure parameter | −0.013 (14) |