title: Crystal structure of 4-formyl-pyridine semicarbazone hemihydrate.
abstract: The mol-ecule of the title compound C7H8N4O·0.5H2O, alternatively called (E)-1-(pyridin-4-yl-methyl-ene)semi-carb-azide 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 mol-ecule 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 intra-molecular N-H⋯N hydrogen bond. In the crystal, mol-ecules are linked into an infinite three-dimensional network by classical N-H⋯Os (s = semicarbazone) and Ow-H⋯N (w = water) hydrogen bonds.
authors.affiliation: Universidade Federal do Paraná, Departamento de Química, C.P. 19081, CEP 81531-980, Curitiba - PR, Brazil.
authors.forename: Mayara Hissami
authors.initials: MH
authors.lastname: Inoue
authors.affiliation: Universidade Federal do Santa Maria, Departamento de Química, CEP 97105-900, Santa Maria - RS, Brazil.
authors.forename: Davi F
authors.initials: DF
authors.lastname: Back
authors.affiliation: Universidade Federal do Santa Maria, Departamento de Química, CEP 97105-900, Santa Maria - RS, Brazil.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Burrow
authors.affiliation: Universidade Federal do Paraná, Departamento de Química, C.P. 19081, CEP 81531-980, Curitiba - PR, Brazil.
authors.forename: Fábio Souza
authors.initials: FS
authors.lastname: Nunes
keywords: 4-formyl­pyridine semicarbazone hemihydrate; N—H⋯O hydrogen bonds; crystal structure