Received 14 November 2012
The title compound, C4H6N3O+·C5H3N2O4-·2H2O or Cyt+·Or-·2H2O, was synthesized by a reaction between cytosine (4-amino-2-hydroxypyrimidine, Cyt) and orotic acid (2,4-dihydroxy-6-carboxypyrimidine, Or) in aqueous solution. The two ions are joined by two N+-HO- (±)-(CAHB) hydrogen bonds, forming a dimer with graph-set motif R22(8). In the crystal, the ion pairs of the asymmetric unit are joined by four N-HO interactions to adjacent dimers, forming hydrogen-bonded rings with R22(8) graph-set motif in a two-dimensional network. The formation of the three-dimensional array is facilitated by water molecules, which act as bridges between structural sub-units linked in R32(8) and R32(7) hydrogen-bonded rings. The orotate anion is essentially planar, as the dihedral angle between the planes defined by the carboxylate group and the uracil fragment is 4.0 (4)°.
For the supramolecular association in proton-transfer adducts containing molecules of biological interest, see: Portalone & Colapietro (2007, 2009); Portalone (2010, 2011); Portalone & Irrera (2011). For the crystal structure of neutral cytosine, see: McClure & Craven (1973). For the crystal structures of orotic acid and its salts, see: Lutz (2001); Portalone (2008); Solbakk (1971). For computation of ring patterns formed by hydrogen bonds in crystal structures, see: Bernstein et al. (1995).
Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis RED (Oxford Diffraction, 2006); data reduction: CrysAlis RED; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: WinGX (Farrugia, 2012); software used to prepare material for publication: WinGX (Farrugia, 2012).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: RZ5024 ).
Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115-119.
Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.
Lutz, M. (2001). Acta Cryst. E57, m103-m105.
McClure, R. J. & Craven, B. M. (1973). Acta Cryst. B29, 1234-1238.
Oxford Diffraction (2006). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.
Portalone, G. (2008). Acta Cryst. E64, o656.
Portalone, G. (2010). Acta Cryst. C66, o295-o301.
Portalone, G. (2011). Chem. Centr. J. 5, 51.
Portalone, G. & Colapietro, M. (2007). J. Chem. Crystallogr. 37, 141-145.
Portalone, G. & Colapietro, M. (2009). J. Chem. Crystallogr. 39, 193-200.
Portalone, G. & Irrera, S. (2011). J. Mol. Struct. 991, 92-96.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.
Solbakk, J. (1971). Acta Chem. Scand. 25, 3006-3018.