2,6-Diamino­pyrimidin-4(3H)-one–4-nitro­benzoic acid (1/1)

In the title compound, C₄H₆N₄O·C₇H₅NO₄, there are two types of base-pairing motifs, one involving a pair of N—H...N hydrogen bonds and the other involving a pair of N—H...O hydrogen bonds. These paired mol­ecules are further linked by N—H...O hydrogen bonds to generate DADA and DDAA (D = donor and A = acceptor) arrays leading to a supra­molecular sheet.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.048
• wR factor = 0.148
• Data-to-parameter ratio = 12.4

checkCIF/PLATON results

No syntax errors found



Alert level A
ABSTM02_ALERT_3_A  Test not performed as the _exptl_absorpt_correction_type
            has not been identified. See test ABSTY_01.
ABSTY01_ALERT_1_A  The absorption correction should be one of the following
            *  none
            *  analytical
            *  integration
            *  numerical
            *  gaussian
            *  empirical
            *  psi-scan
            *  multi-scan
            *  refdelf
            *  sphere
            *  cylinder

Alert level C
ABSTY02_ALERT_1_C  An _exptl_absorpt_correction_type has been given without
            a literature citation. This should be contained in the
            _exptl_absorpt_process_details field.
            Absorption correction given as Not Given
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         N7
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.96
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       3.08

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

   2 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   5 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   5 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Hydrogen bonds are used extensively as a tool to design the structure of molecular crystals, because of their strength, as well as their directional nature, compared to other intermolecular non-covalent interactions (Lehn, 1995). As part of our ougoing studies of hydrogen bonding in molecular arrays (Thanigaimani et al., 2006), we now report the structure of the title 1:1 adduct. The crystal structure of 4-nitrobenzoic acid (Tavale & Pant, 1971) has been already reported in literature.

The asymmetric unit of (I) contains one 2,6-diamino-4-oxo pyrimidine (DAMPY) molecule and one 4-nitrobenzoic (4-NBA) acid molecule (Fig. 1). At the N3 position of the DAMPY ring, there is an increase in internal angle [121.93 (17)°] as compared with 116.75 (16)° at N1. This is due to the presence of a hydrogen atom covalently bonded to the ring nitrogen, N3. In the crystal, the DAMPY molecules form two types of pairing. Two inversion related DAMPY are paired via N—H···N hydrogen bonds involving the 2-amino group and the N1 atom, generating a R₂²(8) motif (Bernstein et al., 1995). In addition to the base pairing, a hydrogen bonded acceptor (O3) bridges the 2-amino and 6-amino group on both side of the pairing, leading to a complementary linear DADA (D = donor in hydrogen bonds; A = acceptor in hydrogen bonds) array of quadruple hydrogen bonds. The resultant rings have the graph-set notation R²₃(8), R²₂(8) and R²₃(8) (Fig 2). This type of DADA array has been observed in trimethoprim (TMP) sulfonate salts (Baskar Raj et al., 2003) and TMP-salicylate methanol solvate (Panneerselvam et al., 2002). The two DAMPY molecules are also paired via a pair of N—H···O hydrogen bonds and the paired molecules are further bridged by the carboxyl group on either side, forming a DDAA array [graph set notation = (R²₃(10), R²₂(8) and R²₃(10)]. In general, either one of the motifs (DADA or DDAA array) has been identified in diaminopyrimidine-carboxylate salts. In rare cases, the presence of both DADA and DDAA arrangement in a single-crystal structure has been reported (Stanley et al., 2005). Interestingly, in the present study also both DADA and DDAA array motifs are arranged in an alternate manner (Fig. 3). These arrays are linked by N—H···O and O—H···O hydrogen bonds to form a supramolecular sheet with alternating R⁴₄(30) and R⁴₄(22) rings. The hydrogen bonds are listed in Table 1.

Related literature

For related literature, see: Baskar Raj et al. (2003); Bernstein et al. (1995); Lehn (1995); Panneerselvam et al. (2002); Stanley et al. (2005); Tavale & Pant (1971); Thanigaimani et al. (2006).

S2. Experimental

Hot ethanol solutions of 2,6-diamino-4-oxopyrimidine (31 mg) and 4-nitrobenzoic acid (42 mg) were mixed in 1:1 molar ratio and warmed over a water bath for half an hour and kept at room temperature for crystallization. Yellow prisms of (I) were obtained after a week via slow evaporation.

S3. Refinement

All hydrogen atoms were placed in idealized locations (C—H = 0.93 Å, N—H = 0.86 Å, O—H = 0.82 Å) and refined as riding with U_iso(H) = 1.2U_eq(carrier).

Computing details

Data collection: XSCANS (Siemens, 1994); cell refinement: XSCANS (Siemens, 1994); data reduction: XSCANS (Siemens, 1994); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: PLATON (Spek, 2003).

Figures

	Fig. 1. View of the molecular structure of (I) showing 30% probability displacement ellipsoids for the non-hydrogen atoms.
	Fig. 2. DADA and DDAA arrays in compound (I). Symmetry Codes: (i) -x + 1, -y + 1, -z + 1; (ii) -x, -y, -z + 1; (iii) x + 1, y + 1, z.
	Fig. 3. A View of supramolecular sheet in compound (I).

2,6-Diaminopyrimidin-4(3H)-one–4-nitrobenzoic acid (1/1)

Crystal data

C4H6N4O·C7H5NO4	Z = 2
Mr = 293.25	F(000) = 304
Triclinic, P1	Dx = 1.557 Mg m^−3
Hall symbol: -P 1	Cu Kα radiation, λ = 1.54178 Å
a = 7.295 (3) Å	Cell parameters from 45 reflections
b = 9.781 (2) Å	θ = 4.8–70.1°
c = 10.104 (3) Å	µ = 1.08 mm^−1
α = 102.27 (3)°	T = 293 K
β = 107.76 (2)°	Prism, yellow
γ = 105.76 (3)°	0.26 × 0.14 × 0.13 mm
V = 625.5 (4) Å^3

Data collection

Siemens AED single-crystal diffractometer	Rint = 0.000
Radiation source: fine-focus sealed tube	θmax = 70.1°, θmin = 4.9°
Graphite monochromator	h = −8→8
ω/2θ scans	k = −11→10
2381 measured reflections	l = −6→12
2381 independent reflections	1 standard reflections every 100 reflections
2115 reflections with I > 2σ(I)	intensity decay: none

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.048	H-atom parameters constrained
wR(F^2) = 0.148	w = 1/[σ^2(Fo^2) + (0.0884P)^2 + 0.1718P] where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max < 0.001
2381 reflections	Δρmax = 0.26 e Å^−3
192 parameters	Δρmin = −0.26 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001Fc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0069 (16)

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All e.s.d.'s are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement on F² for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F²> σ(F²) is used only for calculating -R-factor-obs etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O2	0.2091 (2)	0.28643 (17)	0.68916 (14)	0.0582 (5)
O3	−0.0884 (2)	0.25985 (18)	0.51990 (14)	0.0643 (5)
O4	0.1804 (3)	−0.1464 (2)	0.00742 (17)	0.0831 (7)
O5	0.4695 (3)	−0.1014 (3)	0.1759 (2)	0.1094 (9)
N7	0.3027 (3)	−0.08897 (19)	0.13449 (18)	0.0583 (6)
C7	0.1363 (3)	0.15405 (18)	0.44513 (18)	0.0410 (5)
C8	0.3350 (3)	0.1534 (2)	0.4841 (2)	0.0495 (5)
C9	0.3921 (3)	0.0758 (2)	0.3817 (2)	0.0530 (6)
C10	0.2446 (3)	−0.0024 (2)	0.24225 (19)	0.0465 (5)
C11	0.0462 (3)	−0.0038 (2)	0.2001 (2)	0.0533 (6)
C12	−0.0072 (3)	0.0765 (2)	0.3035 (2)	0.0503 (6)
C13	0.0740 (3)	0.23944 (19)	0.55510 (18)	0.0425 (5)
O1	0.1138 (2)	0.40516 (16)	−0.10381 (12)	0.0554 (4)
N1	0.4530 (2)	0.40898 (17)	0.30142 (14)	0.0443 (5)
N2	0.2528 (2)	0.51813 (19)	0.38755 (15)	0.0517 (5)
N3	0.1934 (2)	0.46264 (16)	0.14123 (14)	0.0441 (5)
N6	0.6491 (3)	0.2979 (2)	0.21274 (17)	0.0605 (6)
C2	0.3024 (3)	0.46214 (19)	0.27595 (17)	0.0408 (5)
C4	0.2278 (3)	0.4014 (2)	0.01796 (17)	0.0439 (5)
C5	0.3826 (3)	0.3424 (2)	0.04147 (18)	0.0468 (5)
C6	0.4933 (3)	0.3499 (2)	0.18368 (18)	0.0438 (5)
H2	0.16380	0.32640	0.74510	0.0870*
H8	0.43080	0.20550	0.57950	0.0590*
H9	0.52620	0.07650	0.40650	0.0640*
H11	−0.04970	−0.05720	0.10490	0.0640*
H12	−0.14010	0.07830	0.27730	0.0600*
H2A	0.31890	0.51910	0.47450	0.0620*
H2B	0.15480	0.55310	0.37220	0.0620*
H3	0.10000	0.50200	0.13160	0.0530*
H5	0.41230	0.29830	−0.03660	0.0560*
H6A	0.71580	0.30340	0.30130	0.0730*
H6B	0.68200	0.25920	0.14280	0.0730*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O2	0.0645 (8)	0.0846 (10)	0.0354 (7)	0.0463 (7)	0.0206 (6)	0.0113 (6)
O3	0.0624 (8)	0.0930 (11)	0.0450 (7)	0.0524 (8)	0.0199 (6)	0.0063 (7)
O4	0.0936 (12)	0.1154 (14)	0.0470 (9)	0.0599 (11)	0.0315 (8)	0.0041 (9)
O5	0.0892 (13)	0.158 (2)	0.0816 (13)	0.0853 (14)	0.0293 (10)	−0.0076 (12)
N7	0.0675 (11)	0.0693 (11)	0.0515 (10)	0.0401 (9)	0.0321 (8)	0.0120 (8)
C7	0.0483 (9)	0.0467 (8)	0.0373 (8)	0.0259 (7)	0.0211 (7)	0.0137 (7)
C8	0.0484 (9)	0.0610 (10)	0.0392 (9)	0.0271 (8)	0.0163 (7)	0.0078 (8)
C9	0.0490 (10)	0.0684 (11)	0.0494 (10)	0.0338 (9)	0.0224 (8)	0.0128 (9)
C10	0.0571 (10)	0.0515 (9)	0.0426 (9)	0.0298 (8)	0.0277 (8)	0.0123 (8)
C11	0.0523 (10)	0.0661 (11)	0.0386 (9)	0.0294 (9)	0.0156 (8)	0.0036 (8)
C12	0.0478 (9)	0.0655 (11)	0.0408 (9)	0.0320 (8)	0.0174 (7)	0.0078 (8)
C13	0.0505 (9)	0.0499 (9)	0.0359 (8)	0.0274 (7)	0.0204 (7)	0.0133 (7)
O1	0.0672 (8)	0.0866 (9)	0.0281 (6)	0.0536 (7)	0.0179 (5)	0.0158 (6)
N1	0.0562 (8)	0.0594 (9)	0.0301 (7)	0.0375 (7)	0.0193 (6)	0.0138 (6)
N2	0.0645 (9)	0.0764 (10)	0.0299 (7)	0.0496 (8)	0.0201 (6)	0.0132 (7)
N3	0.0525 (8)	0.0601 (9)	0.0300 (7)	0.0376 (7)	0.0167 (6)	0.0108 (6)
N6	0.0779 (11)	0.0956 (13)	0.0378 (8)	0.0662 (10)	0.0287 (8)	0.0242 (8)
C2	0.0500 (9)	0.0490 (9)	0.0303 (8)	0.0283 (7)	0.0168 (6)	0.0108 (6)
C4	0.0524 (9)	0.0578 (10)	0.0288 (8)	0.0317 (8)	0.0169 (7)	0.0108 (7)
C5	0.0576 (10)	0.0639 (10)	0.0319 (8)	0.0383 (8)	0.0221 (7)	0.0125 (7)
C6	0.0535 (9)	0.0538 (9)	0.0360 (8)	0.0330 (8)	0.0214 (7)	0.0139 (7)

Geometric parameters (Å, º)

O2—C13	1.301 (2)	N6—H6B	0.8599
O3—C13	1.213 (3)	N6—H6A	0.8603
O4—N7	1.218 (2)	C7—C12	1.383 (3)
O5—N7	1.209 (3)	C7—C13	1.503 (3)
O2—H2	0.8196	C7—C8	1.383 (3)
O1—C4	1.272 (2)	C8—C9	1.386 (3)
N7—C10	1.472 (3)	C9—C10	1.378 (3)
N1—C6	1.360 (2)	C10—C11	1.374 (3)
N1—C2	1.318 (3)	C11—C12	1.388 (3)
N2—C2	1.340 (2)	C8—H8	0.9295
N3—C2	1.353 (2)	C9—H9	0.9305
N3—C4	1.389 (2)	C11—H11	0.9300
N6—C6	1.346 (3)	C12—H12	0.9301
N2—H2A	0.8602	C4—C5	1.383 (3)
N2—H2B	0.8602	C5—C6	1.392 (2)
N3—H3	0.8602	C5—H5	0.9304
C13—O2—H2	109.45	O3—C13—C7	122.20 (16)
O4—N7—O5	122.5 (2)	O2—C13—C7	113.48 (19)
O5—N7—C10	118.68 (18)	O2—C13—O3	124.31 (18)
O4—N7—C10	118.8 (2)	C9—C8—H8	119.84
C2—N1—C6	116.75 (15)	C7—C8—H8	119.76
C2—N3—C4	121.93 (17)	C10—C9—H9	121.00
H2A—N2—H2B	119.99	C8—C9—H9	120.92
C2—N2—H2B	119.97	C10—C11—H11	120.89
C2—N2—H2A	120.04	C12—C11—H11	120.94
C4—N3—H3	119.02	C11—C12—H12	119.80
C2—N3—H3	119.06	C7—C12—H12	119.87
C6—N6—H6B	120.00	N1—C2—N2	119.17 (15)
C6—N6—H6A	119.99	N1—C2—N3	123.04 (17)
H6A—N6—H6B	120.01	N2—C2—N3	117.79 (19)
C8—C7—C13	120.69 (16)	O1—C4—C5	127.16 (18)
C8—C7—C12	120.09 (19)	N3—C4—C5	116.08 (15)
C12—C7—C13	119.2 (2)	O1—C4—N3	116.75 (19)
C7—C8—C9	120.40 (18)	C4—C5—C6	119.02 (18)
C8—C9—C10	118.1 (2)	N1—C6—C5	123.1 (2)
N7—C10—C9	118.3 (2)	N6—C6—C5	121.25 (18)
C9—C10—C11	122.9 (2)	N1—C6—N6	115.62 (16)
N7—C10—C11	118.82 (17)	C4—C5—H5	120.52
C10—C11—C12	118.18 (18)	C6—C5—H5	120.46
C7—C12—C11	120.3 (2)
O5—N7—C10—C9	7.7 (3)	C13—C7—C8—C9	−179.27 (18)
O4—N7—C10—C9	−172.9 (2)	C8—C7—C12—C11	0.8 (3)
O4—N7—C10—C11	7.5 (3)	C13—C7—C12—C11	−179.69 (18)
O5—N7—C10—C11	−171.8 (2)	C8—C7—C13—O2	−11.3 (3)
C2—N1—C6—C5	−0.8 (3)	C12—C7—C8—C9	0.3 (3)
C6—N1—C2—N2	178.30 (18)	C7—C8—C9—C10	−1.4 (3)
C2—N1—C6—N6	179.30 (18)	C8—C9—C10—N7	−178.05 (18)
C6—N1—C2—N3	−1.4 (3)	C8—C9—C10—C11	1.5 (3)
C4—N3—C2—N1	2.5 (3)	N7—C10—C11—C12	179.05 (18)
C4—N3—C2—N2	−177.28 (18)	C9—C10—C11—C12	−0.5 (3)
C2—N3—C4—O1	178.64 (18)	C10—C11—C12—C7	−0.7 (3)
C2—N3—C4—C5	−1.2 (3)	O1—C4—C5—C6	179.3 (2)
C8—C7—C13—O3	169.4 (2)	N3—C4—C5—C6	−0.9 (3)
C12—C7—C13—O2	169.13 (18)	C4—C5—C6—N6	−178.1 (2)
C12—C7—C13—O3	−10.1 (3)	C4—C5—C6—N1	1.9 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O1^i	0.82	1.75	2.550 (2)	166
N2—H2A···N1^ii	0.86	2.19	3.015 (2)	162
N2—H2B···O3^iii	0.86	2.17	2.875 (3)	138
N3—H3···O1^iv	0.86	1.99	2.846 (3)	178
N6—H6A···O3^v	0.86	2.43	3.270 (3)	165
N6—H6B···O4^vi	0.86	2.31	3.159 (3)	168

Symmetry codes: (i) x, y, z+1; (ii) −x+1, −y+1, −z+1; (iii) −x, −y+1, −z+1; (iv) −x, −y+1, −z; (v) x+1, y, z; (vi) −x+1, −y, −z.