Crystal structure of 4-formyl­pyridine semicarbazone hemihydrate

The mol­ecule of the title compound C(7)H(8)N(4)O·0.5H(2)O, alternatively called (E)-1-(pyridin-4-yl­methyl­ene)semi­carb­azide hemihydrate, is in the E conformation and is almost planar; the r.m.s. deviation of the positions of the atoms of the pyridine ring from the best-fit plane is 0.0039 Å. The C, N and O atoms of the rest of the mol­ecule sits close on this plane with a largest deviation of 0.115 (4) Å for the O atom of the semicarbazone moiety. There is an intra­molecular N—H⋯N hydrogen bond. In the crystal, mol­ecules are linked into an infinite three-dimensional network by classical N—H⋯O(s) (s = semicarbazone) and O(w)—H⋯N (w = water) hydrogen bonds.