title: A triclinic polymorph with Z = 3 of N,N'-bis-(2-pyrid-yl)oxamide.
abstract: The asymmetric unit of the title compound, C(12)H(10)N(4)O(2), contains three half-mol-ecules. Each half-mol-ecule is completed by crystallographic inversion symmetry. The title compound, (I), is a polymorph of the structure, (II), reported by Hsu & Chen [Eur. J. Inorg. Chem. (2004), 1488-1493]. In the original report, the compound crystallized in the tetra-gonal space group P[Formula: see text]2(1)c (Z = 8), whereas the structure reported here is triclinic (P[Formula: see text], Z = 3). In both forms, each oxamide mol-ecule is almost planar (with maximum deviations are 0.266 and 0.166 Å) and the O atoms are trans oriented. The principal difference between the two forms lies in the different hydrogen-bonding patterns. In (I), two N-H⋯O and one N-H⋯N hydrogen bonds link the mol-ecules, forming a two-dimensional network, whereas in (II) there are no classical hydrogen bonds to O atoms and only weak C-H⋯O inter-actions are found along with rings of N-H⋯N bonds.
authors.forename: Wan-Ju
authors.initials: WJ
authors.lastname: Zhang
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.forename: Gui-Ling
authors.initials: GL
authors.lastname: Zhang
authors.forename: Xin
authors.initials: X
authors.lastname: Xiao