2,6-Diamino-4-chloro­pyrimidine–benzoic acid (1/1)

Kaliyaperumal Thanigaimani; Nuridayanti Che Khalib; Suhana Arshad; Ibrahim Abdul Razak

doi:10.1107/S160053681204768X

. 2012 Nov 24;68(Pt 12):o3442–o3443. doi: 10.1107/S160053681204768X

2,6-Diamino-4-chloropyrimidine–benzoic acid (1/1)

Kaliyaperumal Thanigaimani ^a, Nuridayanti Che Khalib ^a, Suhana Arshad ^a, Ibrahim Abdul Razak ^a,^*,^‡

PMCID: PMC3589022 PMID: 23476258

Abstract

The benzoic acid molecule of the title compound, C₄H₅ClN₄·C₇H₆O₂, is approximately planar, with a dihedral angle of 1.28 (9)° between the carboxy group and the benzene ring. In the crystal, two acid and two base molecules are linked through N—H⋯O and O—H⋯N hydrogen bonds, forming a centrosymmetric 2 + 2 unit with R ₂ ²(8) and R ₄ ²(8) motifs. These units are further linked through a pair of N—H⋯N hydrogen bonds into a tape structure along [1-20]. The crystal structure also features weak π–π [centroid–centroid distance = 3.5984 (11) Å] and C—H⋯π interactions.

Related literature

For the biological activity of pyrimidine and aminopyrimidine derivatives, see: Hunt et al. (1980 ▶); Baker & Santi (1965 ▶). For related structures, see: Schwalbe & Williams (1982 ▶); Hu et al. (2002 ▶); Chinnakali et al. (1999 ▶); Skovsgaard & Bond (2009 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For bond-length data, see: Allen et al. (1987 ▶). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986 ▶). graphic file with name e-68-o3442-scheme1.jpg

Experimental

Crystal data

C₄H₅ClN₄·C₇H₆O₂
M _r = 266.69
Monoclinic,
a = 8.7817 (17) Å
b = 5.7032 (12) Å
c = 24.026 (4) Å
β = 95.493 (4)°
V = 1197.8 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.32 mm⁻¹
T = 100 K
0.36 × 0.30 × 0.16 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.895, T _max = 0.951
7539 measured reflections
2097 independent reflections
1891 reflections with I > 2σ(I)
R _int = 0.052

Refinement

R[F ² > 2σ(F ²)] = 0.036
wR(F ²) = 0.101
S = 1.09
2097 reflections
183 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Click here for additional data file.^{(21.6KB, cif)}

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S160053681204768X/is5218sup1.cif

e-68-o3442-sup1.cif^{(21.6KB, cif)}

Click here for additional data file.^{(103.2KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S160053681204768X/is5218Isup2.hkl

e-68-o3442-Isup2.hkl^{(103.2KB, hkl)}

Click here for additional data file.^{(4.6KB, cml)}

Supplementary material file. DOI: 10.1107/S160053681204768X/is5218Isup3.cml

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

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

Cg1 is the centroid of the C5–C10 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1O1⋯N2	0.87 (2)	1.74 (2)	2.5976 (18)	168 (3)
N4—H2N4⋯O2	0.88 (2)	2.03 (2)	2.894 (2)	171.2 (18)
N4—H1N4⋯O2ⁱ	0.88 (2)	2.07 (2)	2.902 (2)	158.2 (19)
N3—H1N3⋯N1ⁱⁱ	0.85 (2)	2.18 (2)	3.020 (2)	171 (2)
C9—H9A⋯Cg1ⁱⁱⁱ	0.95	2.99	3.6557 (19)	128

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

Acknowledgments

The authors thank the Malaysian Government and Universiti Sains Malaysia (USM) for the research facilities and Fundamental Research Grant Scheme (FRGS) No. 203/PFIZIK/6711171 to conduct this work. KT thanks The Academy of Sciences for the Developing World and USM for a TWAS–USM fellowship.

supplementary crystallographic information

Comment

Pyrimidine and aminopyrimidine derivatives are biologically important compounds as they occur in nature as components of nucleic acids. Some aminopyrimidine derivatives are used as antifolate drugs (Hunt et al., 1980; Baker & Santi, 1965). The crystal structures of aminopyrimidine derivatives (Schwalbe & Williams, 1982), aminopyrimidine carboxylates (Hu et al., 2002) and co-crystal structures (Chinnakali et al., 1999; Skovsgaard & Bond, 2009) have ben reported. In the present study, hydrogen-bonding patterns in the 2,6-diamino-4-chloropyrimidine–benzoic acid (1/1) co-crystal are investigated.

The asymmetric unit (Fig. 1) contains one 2,6-diamino-4-chloropyrimidine molecule and one benzoic acid molecule. The 2,6-diamino-4-chloropyrimidine molecule is essentially planar, with a maximum deviation of 0.009 (2) Å for atom C4. The carboxyl group of the benzoic acid molecule is twisted slightly from the ring with a dihedral angle between C5–C10 ring and O1/O2/C10/C11 plane being 1.28 (9)°. The bond lengths (Allen et al., 1987) and angles are normal.

In the crystal packing (Fig. 2), the 2,6-diamino-4-chloropyrimidine molecules interact with the carboxylic group of the respective benzoic acid molecules through N4—H2N4···O2 and O1—H1O1···N2 hydrogen bonds, forming a cyclic hydrogen-bonded motif of R₂²(8) (Bernstein et al., 1995). These motifs are centrosymmetrically paired via N4—H1N4···O2ⁱ hydrogen bonds, resulting in a DADA array (Where D is a hydrogen-bond donor and A is a hydrogen-bond acceptor) of quadruple hydrogen bonds (symmetry code in Table 1); this can be represented by the graph-set notations of R₂²(8) and R₄²(8). The quadruple hydrogen-bonding motifs are further extended through a couple of N3—H1N3···N1ⁱⁱ hydrogen bonds (symmetry code in Table 1), leading to the formation of hydrogen-bonded supramolecular tape. The crystal structure is further stabilized by π–π interactions between the pyrimidine (Cg2; N1/N2/C1–C4) rings [Cg2···Cg2 = 3.5984 (11) Å; -x, 1 - y, 1 - z] and C—H···π interactions (Table 1) involving the centroid of the C5–C10 (centroid Cg1) ring.

Experimental

A hot methanol solutions (20 ml) of 2,6-diamino-4-chloropyrimidine (36 mg, Aldrich) and benzoic acid (30 mg, Merck) were mixed and warmed over a heating magnetic stirrer hotplate for a few minutes. The resulting solution was allowed to cool slowly at room temperature and crystals of the title compound (I) appeared after a few days.