Crystal structure and Hirshfeld surface analysis of 2-(4-amino-6-phenyl-1,2,5,6-tetrahydro-1,3,5-triazin-2-ylidene)malononitrile dimethylformamide hemisolvate

In the crystal, molecules are connected into parallel layers via N—H⋯N, N—H⋯O and C—H⋯N hydrogen bonds involving the solvent dimethylformamide molecule, and C—H⋯π interactions, into layers parallel to (001). van der Waals interactions between the layers ensure the stability of the molecular packing.


Chemical context
The synthesis, design, and fabrication of novel biological and therapeutic agents remain some of the main objectives of medicinal and organic chemistry (Khalilov et al., 2021;Naghiyev et al., 2020;Safavora et al., 2019;Yadigarov et al., 2009). The crucial role of triazines is well recognized in the field of synthetic organic chemistry as well as in medicinal chemistry because these N-heterocyclic compounds are structurally similar to adenine and purine (Ganai et al., 2021;Kopylovich et al., 2014;Gurbanov et al., 2020a,b). Moreover, triazines play an important role in photo-triggered structural switching, in the printing market, as ionophores, in the design of functional materials attributed to smart hydrogen bonding, in liquid crystals, self-assembled layers, semiconductors, as analytical reagents for the detection of metal ions, indicators, photoluminescent materials, catalysts, spin-coating films, and optical recording media (Blotny, 2006;Liu et al., 2019). Depending on the attached non-covalent bond donor or acceptor substituents, the functional properties of N-heterocyclic compounds and their metal complexes can be improved (Ma et al., 2020(Ma et al., , 2021Mahmudov et al., 2020Mahmudov et al., , 2021Mahmudov et al., , 2022. Substituted triazine derivatives can be synthesized by several different routes. The most common protocols are nucleophilic aromatic substitution of cyanuric chloride, cycloaddition reactions to form the triazine ring, and cyclotrimerization of organic cyanamides and nitriles. Notably, the direct multicomponent reaction is both effective and easy, and can yield the desired compounds in a single-step reaction. Herein, we have synthesized 2-(4-amino-6-phenyl-5,6-dihydro-1,3,5triazin-2(1H)-ylidene)malononitrile by a one-pot multicomponent reaction of (E)-1-[amino(1H-pyrazol-1-yl)methylene]guanidinium chloride with benzaldehyde in the presence of malononitrile in methanol.

Structural commentary
The title compound ( Fig. 1) contains the two independent molecules (molecule I with N1 and molecule II with N7) and one dimethylformamide solvent molecule in the asymmetric unit. The triazine ring (N1-N3/C1-C3) in I adopts a distorted envelope conformation with puckering parameters (Cremer & Pople, 1975) Q(2) = 0.2149 (17) Å and '(2) = 246.1 (4) , while the triazine ring (N7-N9/C13-C15) in II has an envelope conformation [Q(2) = 0.2242 (17) Å , '(2) = 238.4 (4) ]. Fig. 2 shows the overlay of molecules I and II in the asymmetric unit, with an r.m.s. deviation of 0.170 Å . The phenyl ring of molecule I is disordered over two sets of sites with an occupancy ratio of 0.67 (3):0.33 (3) (major component C4-C9 and minor component C4A-C9A). These disordered phenyl rings are at a dihedral angle of 6.0 (13) to each other and the major and minor disorder components make dihedral angles of 86.9 (5) and 87.5 (12) , respectively, with the mean plane of the triazine ring of molecule I. The phenyl ring (C16-C21) in II makes a dihedral angle of 86.65 (9) with the mean plane of the triazine ring. There is one stereogenic center in both racemic molecules and the chirality about atoms C1 in I and C13 in II is S in the chosen asymmetric unit. Molecules I and II have normal geometric parameters.

Supramolecular features and Hirshfeld surface analysis
In the crystal, molecules I and II are linked by intermolecular N-HÁ Á ÁN, N-HÁ Á ÁO and C-HÁ Á ÁN hydrogen bonds (Table 1)  Least-squares overlay image (OLEX2; Dolomanov et al., 2009) of the two independent molecules (I and II) in the asymmetric unit of the title compound. Only the major component of disorder for molecule I is shown. Color code: carbon (gray), hydrogen (white) and nitrogen (blue).

Figure 1
The molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level. Only the major disordered fragments are shown for clarity. Table 1 Hydrogen-bond geometry (Å , ).
Cg2 and Cg5 are the centroids of the major component of the C4-C9 phenyl ring of molecule I and the C16-C21 phenyl ring of molecule II, respectively. Hirshfeld surfaces for both molecules were calculated using Crystal Explorer17 (Turner et al., 2017). The d norm mappings for molecules I and II were performed in the ranges À0.4528 to +1.2207 a.u. and À0.4546 to +1.3342 a.u., respectively. The locations of the N-HÁ Á ÁN, N-HÁ Á ÁO and C-HÁ Á ÁN interactions are shown by intense red circles on the d norm surfaces (Fig. 7a,b for I and Fig. 7c,d for II).    View down the c axis of the N-HÁ Á ÁN, N-HÁ Á ÁO and C-HÁ Á ÁN hydrogen bonds (dashed lines) in the title compound. The minor disordered components have been omitted for clarity.

Figure 5
A partial view down the a axis of the C-HÁ Á Á interactions (dashed lines) in the title compound. The minor disordered components and hydrogen atoms not involved in hydrogen bonding have been omitted for clarity.

Figure 6
A partial view down the c axis of the C-HÁ Á Á interactions (dashed lines) in the title compound. The minor disordered components and hydrogen atoms not involved in hydrogen bonding have been omitted for clarity.
In the crystal of (B), the dihydrotriazine nucleus is protonated at N5, where positive-charge delocalization is maximized. Except for one H atom on N4, all of the N-bound H atoms are involved in either HÁ Á ÁN or HÁ Á ÁCI interactions.   Front and back views of the three-dimensional Hirshfeld surfaces of molecules I (a,b) and II (c,d) of the title compound. Table 2 Summary of short interatomic contacts (Å ) in the title compound.