2-Amino-4-phenyl-4H,10H-1,3,5-triazino[1,2-a]benzimidazol-3-ium chloride

Shaaban K Mohamed; Mahmoud A A El-Remaily; Ahmed M Soliman; Hossam Abdel-Ghany; Seik Weng Ng

doi:10.1107/S1600536811013766

. 2011 Apr 16;67(Pt 5):o1154. doi: 10.1107/S1600536811013766

2-Amino-4-phenyl-4H,10H-1,3,5-triazino[1,2-a]benzimidazol-3-ium chloride

Shaaban K Mohamed ^a, Mahmoud A A El-Remaily ^b, Ahmed M Soliman ^b, Hossam Abdel-Ghany ^b, Seik Weng Ng ^c,^*

PMCID: PMC3089182 PMID: 21754462

Abstract

2-Guanidinobenzimidazole condenses with benzaldehyde in the presence of hydrochloric acid to form 2-amino-3,4-dihydro-4-phenyl-1,3,5-triazino[1,2-a]benzimidazole, which was isolated as its hydrochloride, C₁₅H₁₄N₅ ⁺·Cl⁻. The positive charge of the cation is formally placed on the double-bonded N atom of the dihydrotriazine ring. The six-membered dihydrotriazine that is fused with the benzimidazole ring system is relatively flat (r.m.s. deviation = 0.106 Å), with the methine C atom deviating most [0.164 (1) Å] from the mean-square plane. The phenyl ring connected to the methine C atom is disordered over two positions in a 0.558 (1):0.442 (1) ratio; the two orientations are aligned at 85.1 (1) and 89.6 (1)° with respect to the dihydrotriazine ring. In the crystal, adjacent cations and anions are linked by N—H⋯N and N—H⋯Cl hydrogen bonds, generating a double chain running along the b axis.

Related literature

For the synthesis, see: Dolzhenko & Chui (2006 ▶); Martin et al. (1981 ▶); Nagarajan et al. (1970 ▶).

Experimental

Crystal data

C₁₅H₁₄N₅ ⁺·Cl⁻
M _r = 299.76
Triclinic,
a = 8.6454 (5) Å
b = 9.0440 (4) Å
c = 9.7182 (6) Å
α = 83.306 (4)°
β = 70.956 (5)°
γ = 81.523 (4)°
V = 708.51 (7) Å³
Z = 2
Cu Kα radiation
μ = 2.39 mm⁻¹
T = 100 K
0.20 × 0.20 × 0.02 mm

Data collection

Agilent SuperNova Dual diffractometer with an Atlas detector
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010 ▶) T _min = 0.647, T _max = 0.954
7924 measured reflections
2818 independent reflections
2667 reflections with I > 2σ(I)
R _int = 0.017

Refinement

R[F ² > 2σ(F ²)] = 0.040
wR(F ²) = 0.106
S = 1.01
2818 reflections
237 parameters
6 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.33 e Å⁻³
Δρ_min = −0.29 e Å⁻³

Data collection: CrysAlis PRO (Agilent, 2010 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: X-SEED (Barbour, 2001 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811013766/bt5515sup1.cif

e-67-o1154-sup1.cif^{(20.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811013766/bt5515Isup2.hkl

e-67-o1154-Isup2.hkl^{(138.3KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯Cl1	0.88 (1)	2.23 (1)	3.1033 (16)	172 (2)
N4—H4⋯Cl1ⁱ	0.88 (1)	2.25 (1)	3.1060 (14)	165 (2)
N5—H3⋯N3ⁱⁱ	0.89 (1)	2.08 (1)	2.9643 (19)	176 (2)
N5—H2⋯Cl1ⁱⁱ	0.88 (1)	2.66 (2)	3.3147 (14)	132 (2)

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

We thank Manchester Metropolitan University, Sohag University and the University of Malaya for supporting this study.

supplementary crystallographic information

Comment

2-Guanidinobenzimidazole and aromatic aldehydes readily condense to form 2-amino-[1,3,5]triazino[1,2-a]benzimidazoles (Nagarajan et al., 1970; Martin et al., 1981); such compounds exhibit dihydrofolate reductase inhibitory activity (Dolzhenko & Chui, 2006). We added acetylacetone in the synthesis as the resulting compound possesses an amino subsitutent that is capable of further condensation, but the hydrochloric acid we used in the synthesis protonated the compound. The positive charge of the salt (Scheme I) is formally placed on the double-bonded N atom of the dihydrotriazine ring. The six-memebered dihydrotriazine that is fused with the benzimidazole ring-system is relatively flat, with the methine C deviating most from the mean-square plane. The phenyl ring that is connected to the methine C atom is disordered over two positions; the two orientations are aligned at nearly 90 ° with respect to the dihydrotriazine ring (Fig. 1). Adjacent cations and anions are linked by N–H···N and N–H···Cl hydrogen bonds to generate a linear chain motif (Table 1).

Experimental

2-Guanidinobenzimidazole (1H-benzo[d]imidazol-2-yliminomethanediamine) (10 mmol), benzaldehyde (10 mmol) and excess of cyclohexanone (approx. 10 ml) along with few drops of concentrated hydrochloric acid was heated in N,N-dimethylformamide (50 ml) for 30 minutes. The product was collected and recrystallized from ethanol; m.p. 623 K.