Co II -catalysed synthesis of N -(4-meth-oxy-phen-yl)-5-(pyridin-4-yl)-1,3,4-oxa-diazol-2-amine hemi-hydro-chloride monohydrate.

The title compound, C 14 H 12 N 4 O 2 ·0.5HCl·H 2 O or H(C 14 H 12 N 4 O 2 ) 2 + ·Cl - ·2H 2 O, arose from the unexpected cyclization of isonicotinoyl- N -phenyl hydrazine carbo-thio-amide catalysed by cobalt(II) acetate. The organic mol-ecule is almost planar and a symmetric N⋯H + ⋯N hydrogen bond links two of them together, with the H atom lying on a crystallographic twofold axis. The extended structure features N-H⋯O and O-H⋯Cl hydrogen bonds, which generate [001] chains. Weak C-H⋯Cl inter-actions cross-link the chains. The chloride ion has site symmetry 2. The major contributions to the Hirshfeld surface are from H⋯H (47.1%), Cl⋯H/H⋯Cl (total 10.8%), O⋯H/H⋯O (7.4%) and N⋯H/H⋯N (6.7%) inter-actions.