Crystal structure and Hirshfeld surface analysis of 2,4-diamino-6-phenyl-1,3,5-triazin-1-ium 4-methylbenzenesulfonate

The asymmetric unit consists of a 2,4-diamino-6-phenyl-1,3,5-triazin-1-ium cation and a 4-methylbenzoate anion. The protonated nitrogen and amino group nitrogen atoms are involved in hydrogen bonding with the sulfonate oxygen atoms through a pair of intermolecular N—H⋯O hydrogen bonds. The inversion-related molecules are further linked by four N—H⋯O intermolecular interations to produce a complementary DDAA hydrogen-bonded array. Hirshfeld surface analysis was employed to further examine the intermolecular interactions.

In the title molecular salt, C 9 H 10 N 5 + ÁC 7 H 7 O 3 S À , the asymmetric unit consists of a 2,4-diamino-6-phenyl-1,3,5-triazin-1-ium cation and a 4-methylbenzenesulfonate anion. The cation is protonated at the N atom lying between the amine and phenyl substituents. The protonated N and amino-group N atoms are involved in hydrogen bonding with the sulfonate O atoms through a pair of intermolecular N-HÁ Á ÁO hydrogen bonds, giving rise to a hydrogen-bonded cyclic motif with R 2 2 (8) graph-set notation. The inversion-related molecules are further linked by four N-HÁ Á ÁO intermolecular interactions to produce a complementary DDAA (D = donor, A = acceptor) hydrogen-bonded array, forming R 2 2 (8), R 4 2 (8) and R 2 2 (8) ring motifs. The centrosymmetrically paired cations form R 2 2 (8) ring motifs through base-pairing via N-HÁ Á ÁN hydrogen bonds. In addition, another R 3 3 (10) motif is formed between centrosymetrically paired cations and a sulfonate anion via N-HÁ Á ÁO hydrogen bonds. The crystal structure also features weak S OÁ Á Á andinteractions. Hirshfeld surface and fingerprint plots were employed in order to further study the intermolecular interactions.

Chemical context
Triazine derivatives have been found to possess a wide variety of biological activities such as anticancer (El-Gendy et al., 2001;Abdel-Rahman et al., 1999), antitumour (Menicagli et al., 2004) and anti-inflammatory (El-Massry et al., 1999) activities. In addition, many s-triazine derivatives have been found to exhibit antibacterial (Jyoti et al., 2003) and herbicidal activity. The 1,3,5-triazine moieties are of particular interest because of their potentially large non-linear optical response (Marchewka et al., 2003). Triazine derivatives of melamine and benzoguanamine are used to manufacture resins (Ricciotti et al., 2013). They are used as preservatives in oil-field applications and as disinfectants, industrial deodorants and as a biocide in water treatments. Triazine derivatives have been used appreciably as a valuable constructing unit of subtle architectures consisting of organic and inorganic hybrid frameworks (Mathias et al., 1994;Zerkowski et al., 1994;MacDonald & Whitesides, 1994;Guru Row et al., 1999;Krische & Lehn, 2000;Sherrington & Taskinen, 2001). Herein the crystal structure of 2,4-diamino-6-phenyl-1,3,5-triazine-1ium-4-methylbenzene sulfonate is described. Hirshfeld surface analysis and two-dimensional fingerprint plots were employed to quantify the percentage contributions of the intermolecular interactions present in the molecule.

Supramolecular features
In the crystal, the protonated nitrogen (N5) and amino group nitrogen (N4) atoms are involved in hydrogen bonding with the 4-methylbenzene sulfonate oxygen atoms O2 and O3 through a pair of intermolecular N-HÁ Á ÁO hydrogen bonds, giving rise to a hydrogen-bonded R 2 2 (8) cyclic graph-set motif ( Fig. 1, Table 1). Here the sulfonate oxygen atoms mimic the role of carboxylate oxygen atoms. The inversion-related molecules are further linked by four N-HÁ Á ÁO hydrogen bonds, forming an another R 2 4 (8) ring motif to produce a DDAA array of quadruple hydrogen bonds. This type of conjoined hydrogen-bonded ring motifs can be represented as R 2 2 (8), R 2 4 (8) and R 2 2 (8), repectively (Fig. 2). The inversionrelated triazinium bases are paired by two N-HÁ Á ÁN hydrogen bonds, generating an R 2 2 (8) graph-set motif. In addition, another R 3 3 (10) ring motif is formed between centrosymetrically paired cations and a sulfonate anion via N-HÁ Á ÁO hydrogen bonds. One of the sulfonate oxygen atoms acts as an acceptor of bifurcated hydrogen bonds. Overall, these hydrogen bonds generate chains along (100).

Synthesis and crystallization
The title compound was prepared by mixing a hot methanolic solution (20 ml) of 2,4-diamino-6-phenyl-1,3,5-triazine (0.187 g) and a hot methanolic solution (10 ml) of 4-methylbenzene sulfonic acid (0.172 g) in 1:1 molar ratio. The reaction mixture was warmed over a water bath for a few minutes. The resultant solution was then allowed to cool slowly at room temperature. After a few days, colourless block-shaped crystals were separated out.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The C-and N-bound H atoms were placed in calculated positions and were included in the refinement in the riding-model approximation: C-H = 0.93 Å and N-H = 0.86 Å with U iso (H) set to 1.2-1.5U eq (C) or 1.3U eq (N).
A view of the three-dimensional Hirshfeld surface of the title compound.