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

The title compound, CHNO·0.5HCl·HO or H(CHNO) ·Cl·2HO, arose from the unexpected cyclization of isonicotinoyl--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.