Received 27 July 2006
aInstituto de Tecnologia em Fármacos, Far-Manguinhos, FIOCRUZ, 21041-250, Rio de Janeiro, RJ, Brazil,bInstituto de Química, Departamento de Química Inorgânica, Universidade Federal do Rio de Janeiro, CP 68563, 21945-970 Rio de Janeiro, RJ, Brazil,cDepartment of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen AB24 3UE, Scotland, and dSchool of Chemistry, University of St Andrews, Fife KY16 9ST, Scotland
Correspondence e-mail: email@example.com
Molecules of the title compound, C5H6N4O, are linked into a three-dimensional framework structure by a combination of N-HO, N-HN and C-HO hydrogen bonds.
As part of our general study of the supramolecular structures of amine and hydrazine derivatives, we report here the molecular and supramolecular structure of the title compound, (I). Within the hydrazino fragment, the coordination at C7 and N2 is planar within experimental uncertainty, while the coordination at N3 is markedly pyramidal (Fig. 1). Apart from the H atoms bonded to atom N3, the molecule is effectively planar, as shown by the key torsion angles (Table 1); the bond distances and angles show no unexpected features.
The molecules are linked by hydrogen bonds (Table 2) into a three-dimensional framework of some complexity, whose formation can, nonetheless, be readily analysed in terms of two simple substructures. In the first of these substructures, atom N3 in the molecule at (x, y, z) acts as hydrogen-bond donor, via H31 and H32, respectively, to atoms O1 in the molecules at (1 - x, 1 - y, 1 - z) and (-x, 1 - y, 1 - z), so generating by inversion a chain of edge-fused R22(10) (Bernstein et al., 1995) rings running along (x, , ) (Fig. 2). The rings containing H31 are centred at (n + , , ), where n = zero or an integer) and those containing H32 are centred at (n, , ) (n = zero or integer).
In the second substructure, atom N2 in the molecule at (x, y, z), which lies in the chain of rings along (x, , ), acts as hydrogen-bond donor to atom N4 in the molecule at (1 - x, - y, + z), which lies in the chain along (x, 0, 1); at the same time, atom C3 at (1 - x, - y, + z) acts as donor to atom N1 in the molecule at (x, y, z), so forming an R22(8) motif (Fig. 3). Propagation of this motif by the symmetry operations of the space group then links the chain of rings along (x, , ) directly to the four chains along (x, 0, 0), (x, 0, 1), (x, 1, 0) and (x, 1, 1), thence linking all of the  chains into a single three-dimensional framework structure (Fig. 4).
| || Figure 1 |
The molecular structure of compound (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.
| || Figure 2 |
A stereoview of part of the crystal structure of compound (I), showing the formation of a chain of edge-fused rings along (x, , ). For the sake of clarity, H atoms not involved in the motifs shown have been omitted.
| || Figure 3 |
Part of the crystal structure of compound (I), showing the concerted action of the N-HN and C-HN hydrogen bonds. For the sake of clarity, H atoms not involved in the motif shown have been omitted. Atoms marked with an asterisk (*) or a hash (#) are at the symmetry positions (1 + x, - y, + z) and (-1 + x, - y, - + z), respectively.
| || Figure 4 |
A projection down  of part of the crystal structure of compound (I), showing the linking of the chain of rings along (x, , ) to four adjacent chains. For the sake of clarity, H atoms not involved in the motifs shown have been omitted.
A solution of methyl pyrazinecarboxylate and a fivefold molar excess of hydrazine hydrate was held at 353 K for 12 h. The solvent was removed under reduced pressure and the residue was purified by washing successively with cold ethanol and with diethyl ether to give crystalline (I) (yield 87%, m.p. 431-432 K). NMR (DMSO-d6): (H) 10.14 (1H, s, NH), 9.13 (1H, d, J = 1.2 Hz, H3), 8.84 (1H, d, J = 2.8 Hz, H6), 8.70 (1H, dd, J = 1.2 and 2.8 Hz, H5), 4.70 (2H, s, NH2); (C) 161.4, 147.2, 144.8, 143.4, 143.1. IR (KBr disk, cm-1) 3306-3238 (NH), 1648 (CO).
All H atoms were located in difference maps, and then treated as riding atoms, with C-H = 0.95 Å and N-H = 0.92 (NH2) or 0.96 Å (NH), with Uiso(H) = 1.2Ueq(C,N).
Data collection: COLLECT (Hooft, 1999); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: OSCAIL (McArdle, 2003) and SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: OSCAIL and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).
X-Ray data were collected at the EPSRC National X-ray Crystallography Service, University of Southampton, England; the authors thank the staff of the Service for all their help and advice. JLW thanks CNPq and FAPERJ for financial support.
Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.
Ferguson, G. (1999). PRPKAPPA. University of Guelph, Canada.
Hooft, R. W. W. (1999). COLLECT. Nonius BV, Delft, The Netherlands.
McArdle, P. (2003). OSCAIL for Windows. Version 10. Crystallography Centre, Chemistry Department, NUI Galway, Ireland.
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.
Sheldrick, G. M. (2003). SADABS. Version 2.10. University of Göttingen, Germany.
Spek, A. L. (2003). J. Appl. Cryst. 36, 7-13.