2-Amino­pyrimidinium hydrogen sulfate

In the crystal structure of the title compound, C₄H₆N₃⁺·HSO₄⁻, hydrogen sulfate anions self-assemble through O—H⋯O hydrogen bonds, forming chains along the b axis, while the cations form centrosymmetric pairs via N—H⋯N hydrogen bonds. The 2-amino­pyrimidinium pairs are linked to the sulfate anions via N—H⋯O hydrogen bonds, forming a two-dimensional network parallel to (10). In addition, weak inter­molecular C—H⋯O contacts generate a three-dimensional network.

Related literature

For the biological properties of pyrimidines, see: Rabie et al. (2007); Rival et al. (1991). For applications of amino­pyrimidines, see: Rospenk & Koll (2007). For amino­pyrimidine salts, see: Hemamalini et al. (2005); Childs et al. (2007); Lee et al. (2003); Ye et al. (2002). For sulfate salts with organic cations, see: Xu et al. (2009a,b).

Experimental

Crystal data

• C₄H₆N₃⁺·HSO₄⁻

• M_r = 193.19

• Monoclinic, P 2₁ /c

• a = 8.388 (2) Å

• b = 5.208 (3) Å

• c = 18.468 (4) Å

• β = 112.84 (2)°

• V = 743.6 (5) ų

• Z = 4

• Ag Kα radiation

• λ = 0.56087 Å

• μ = 0.22 mm⁻¹

• T = 293 K

• 0.25 × 0.21 × 0.15 mm

Data collection

• Enraf–Nonius CAD-4 diffractometer

• 3738 measured reflections

• 3647 independent reflections

• 2520 reflections with I > 2σ(I)

• R_int = 0.015

• 2 standard reflections every 120 min intensity decay: 1%

Refinement

• R[F² > 2σ(F²)] = 0.056

• wR(F²) = 0.159

• S = 1.07

• 3647 reflections

• 110 parameters

• H-atom parameters constrained

• Δρ_max = 0.82 e Å⁻³

• Δρ_min = −0.71 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O4^i	0.82	1.79	2.6100 (19)	174
N1—H1B⋯O1^ii	0.86	2.38	3.140 (2)	148
N1—H1B⋯O4	0.86	2.58	3.155 (2)	125
N1—H1A⋯N3^iii	0.86	2.16	3.017 (2)	172
N2—H2⋯O3	0.86	1.91	2.756 (2)	168
C2—H2A⋯O3^iv	0.93	2.40	3.294 (2)	160
C3—H3⋯O2^v	0.93	2.51	3.262 (3)	138
C4—H4⋯O4^vi	0.93	2.53	3.316 (2)	142
Symmetry codes: (i) ; (ii) x, y+1, z; (iii) -x+2, -y+1, -z+1; (iv) ; (v) ; (vi) -x+2, -y, -z+1.

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS86 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996) and DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999).

Supporting information

S1. Comment

Substantial attention has recently been focused on pyrimidine and its derivatives for their interesting properties as fungicides, vermicides, insecticides (Rabie et al., 2007), antifungal agents and antiviral agents (Rival et al., 1991). In particular, aminopyrimidines have been recognized as interesting nucleic bases, like cytosine, adenine and guanine which are responsible for molecular recognition and replication of DNA, through the formation and breakage of N—H···N hydrogen bonds (Rospenk & Koll, 2007). In continuation of our research on materials which could have interesting applications we report herein the synthesis and crystal structure of the title compound (I).

The asymmetric unit of the title compound (Fig. 1) consists of one hydrogen sulfate anion and one protonated 2-aminopyrimidine. The crystal packing of (I) is characterized by infinite chains built by HSO₄^- anions extending along the b-direction. These chains are interconnected by cationic moieties via intermolecular N—H···O and C—H···O hydrogen bonds (Table 1) resulting in three-dimensional supra-molecular structure (Fig. 2).

As can be seen in table 1, the O1—H1···O4ⁱ hydrogen bond links two adjacent hydrogen sulfate anions generating corrugated chains stacked along c axis (Fig. 2). In the sulfate anion, the S—O bond [1.569 (2) Å] involving the O atom bearing the acid H atom is longer than the other three S—O bonds, which range from 1.429 (1) to 1.459 (1) Å because of the bond multiplicity and the electronic mesomerism as reported previously in the hydrogen sulfate ion (Xu et al., 2009a,b).

With regard to the organic framework, the neighbouring cations of 2-aminopyrimidine linked by the hydrogen bonds N1–H1A···N3 (2 - x, 1 - y, 1 - z) and N3···H1A–N1 (2 - x, 1 - y, 1 - z) form the cyclic dimer of [C₄N₂H₄NH₂]²⁺ ₂. The cationic arrangement in crystal structure of 2-amino-4,6-dimethylpyrimidinium hydrogen sulfate (Hemamalini et al., 2005) is closely related to that seen in the title compound. The dimers of the 2-aminopyrimidinium cations with planar rings (r.m.s. deviation = 0.008 Å) are connected to HSO₄^- chains by hydrogen bonds N1–H1B···O4, N1–H1B···O1 (x, y + 1, z) and N2–H2···O3 to form a two-dimensional network (Fig. 2) which is linked into a three-dimensional network through weak intermolecular hydrogen bonds. These observations are similar to that of other 2-aminopyrimidinium salts (Childs et al., 2007; Lee et al., 2003; Ye et al., 2002).

Related literature

For the biological properties of pyrimidines, see: Rabie et al. (2007); Rival et al. (1991). For applications of aminopyrimidines, see: Rospenk & Koll (2007). For aminopyrimidine salts, see: Hemamalini et al. (2005); Childs et al. (2007); Lee et al. (2003); Ye et al. (2002). For sulfate salts with organic cations, see: Xu et al. (2009a,b).

S2. Experimental

To a solution of 2-aminopyrimidine (0.19 g, 2 mmol) dissolved in a mixture of water/ethanol (10/5 ml) was added dropwise 2 mmol (0.15 ml) of commercial H₂SO₄ (98%, Aldrich). The reaction mixture was stirred and left under slowly evaporation at room temperature until formation of large colorless single crystals of the title compound.

S3. Refinement

All H atoms attached to C, N and O atoms were fixed geometrically and treated as riding with C—H = 0.93 Å, N—H= 0.86 Å and O—H = 0.82 Å with U_iso(H) = 1.2 U_eq(C, N) or 1.5 U_eq(O)

Computing details

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS86 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996) and DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999).

Figures

	Fig. 1. The asymmetric unit of (I). Displacement ellipsoids are drawn at the 30% probability level. H atoms are represented as spheres of arbitrary radii. Hydrogen bonds are represented as dashed lines.
	Fig. 2. Projection of (I) along the b axis. The H-atoms not involved in H-bonding are omitted. H bonds are shown as dashed lines.

2-Aminopyrimidinium hydrogen sulfate

Crystal data

C4H6N3^+·HSO4^−	F(000) = 400
Mr = 193.19	Dx = 1.726 Mg m^−3
Monoclinic, P21/c	Ag Kα radiation, λ = 0.56087 Å
Hall symbol: -P 2ybc	Cell parameters from 25 reflections
a = 8.388 (2) Å	θ = 9–11°
b = 5.208 (3) Å	µ = 0.22 mm^−1
c = 18.468 (4) Å	T = 293 K
β = 112.84 (2)°	Prism, colorless
V = 743.6 (5) Å^3	0.25 × 0.21 × 0.15 mm
Z = 4

Data collection

Enraf–Nonius CAD-4 diffractometer	Rint = 0.015
Radiation source: fine-focus sealed tube	θmax = 28.0°, θmin = 2.1°
Graphite monochromator	h = −14→13
non–profiled ω scans	k = −8→0
3738 measured reflections	l = −30→13
3647 independent reflections	2 standard reflections every 120 min
2520 reflections with I > 2σ(I)	intensity decay: 1%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.056	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.159	H-atom parameters constrained
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0919P)^2 + 0.0037P] where P = (Fo^2 + 2Fc^2)/3
3647 reflections	(Δ/σ)max < 0.001
110 parameters	Δρmax = 0.82 e Å^−3
0 restraints	Δρmin = −0.71 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) 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
S	0.67465 (5)	−0.13645 (8)	0.21545 (2)	0.02768 (11)
O1	0.66596 (17)	−0.4361 (3)	0.22175 (9)	0.0400 (3)
H1	0.5717	−0.4774	0.2218	0.060*
O2	0.5491 (2)	−0.0595 (3)	0.14085 (8)	0.0515 (4)
O3	0.85241 (16)	−0.0898 (3)	0.22478 (7)	0.0365 (3)
O4	0.64241 (17)	−0.0315 (3)	0.28174 (8)	0.0408 (3)
N1	0.9071 (2)	0.3742 (3)	0.39016 (9)	0.0430 (4)
H1A	0.8905	0.4952	0.4181	0.052*
H1B	0.8390	0.3583	0.3416	0.052*
N2	1.06403 (19)	0.0245 (3)	0.37781 (8)	0.0319 (3)
H2	0.9966	0.0117	0.3291	0.038*
N3	1.1419 (2)	0.2419 (3)	0.49787 (8)	0.0358 (3)
C1	1.0366 (2)	0.2136 (3)	0.42160 (9)	0.0295 (3)
C2	1.1941 (2)	−0.1444 (3)	0.40855 (11)	0.0376 (3)
H2A	1.2105	−0.2737	0.3774	0.045*
C3	1.3011 (3)	−0.1248 (4)	0.48528 (12)	0.0429 (4)
H3	1.3912	−0.2404	0.5085	0.051*
C4	1.2703 (3)	0.0753 (4)	0.52752 (10)	0.0418 (4)
H4	1.3442	0.0939	0.5799	0.050*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S	0.03166 (18)	0.02383 (17)	0.02574 (16)	−0.00177 (13)	0.00914 (13)	−0.00139 (13)
O1	0.0418 (7)	0.0245 (5)	0.0581 (8)	−0.0021 (5)	0.0240 (6)	−0.0020 (5)
O2	0.0539 (9)	0.0493 (9)	0.0337 (6)	−0.0035 (7)	−0.0023 (6)	0.0068 (6)
O3	0.0380 (6)	0.0388 (7)	0.0365 (6)	−0.0084 (5)	0.0186 (5)	−0.0057 (5)
O4	0.0423 (7)	0.0420 (7)	0.0409 (6)	0.0016 (5)	0.0192 (5)	−0.0115 (5)
N1	0.0456 (8)	0.0428 (9)	0.0325 (7)	0.0091 (7)	0.0062 (6)	−0.0061 (6)
N2	0.0408 (7)	0.0292 (6)	0.0263 (5)	−0.0040 (5)	0.0135 (5)	−0.0039 (5)
N3	0.0420 (7)	0.0361 (8)	0.0250 (6)	−0.0001 (6)	0.0084 (5)	−0.0043 (5)
C1	0.0361 (7)	0.0266 (6)	0.0255 (6)	−0.0042 (6)	0.0116 (5)	−0.0025 (5)
C2	0.0461 (9)	0.0287 (7)	0.0438 (9)	−0.0005 (7)	0.0238 (8)	−0.0030 (7)
C3	0.0450 (9)	0.0396 (10)	0.0436 (9)	0.0093 (8)	0.0168 (8)	0.0075 (8)
C4	0.0439 (9)	0.0468 (10)	0.0289 (7)	0.0016 (8)	0.0078 (7)	0.0022 (7)

Geometric parameters (Å, º)

S—O2	1.4288 (14)	N2—C1	1.350 (2)
S—O3	1.4535 (13)	N2—H2	0.8600
S—O4	1.4588 (13)	N3—C4	1.324 (3)
S—O1	1.5690 (17)	N3—C1	1.349 (2)
O1—H1	0.8200	C2—C3	1.355 (3)
N1—C1	1.314 (2)	C2—H2A	0.9300
N1—H1A	0.8600	C3—C4	1.385 (3)
N1—H1B	0.8600	C3—H3	0.9300
N2—C2	1.343 (2)	C4—H4	0.9300
O2—S—O3	113.94 (9)	C4—N3—C1	117.25 (16)
O2—S—O4	113.37 (10)	N1—C1—N3	119.05 (16)
O3—S—O4	110.72 (8)	N1—C1—N2	120.26 (15)
O2—S—O1	108.21 (9)	N3—C1—N2	120.69 (16)
O3—S—O1	103.46 (8)	N2—C2—C3	119.50 (17)
O4—S—O1	106.34 (9)	N2—C2—H2A	120.3
S—O1—H1	109.5	C3—C2—H2A	120.3
C1—N1—H1A	120.0	C2—C3—C4	116.90 (18)
C1—N1—H1B	120.0	C2—C3—H3	121.5
H1A—N1—H1B	120.0	C4—C3—H3	121.5
C2—N2—C1	121.60 (15)	N3—C4—C3	124.04 (17)
C2—N2—H2	119.2	N3—C4—H4	118.0
C1—N2—H2	119.2	C3—C4—H4	118.0

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O4^i	0.82	1.79	2.6100 (19)	174
N1—H1B···O1^ii	0.86	2.38	3.140 (2)	148
N1—H1B···O4	0.86	2.58	3.155 (2)	125
N1—H1A···N3^iii	0.86	2.16	3.017 (2)	172
N2—H2···O3	0.86	1.91	2.756 (2)	168
C2—H2A···O3^iv	0.93	2.40	3.294 (2)	160
C3—H3···O2^v	0.93	2.51	3.262 (3)	138
C4—H4···O4^vi	0.93	2.53	3.316 (2)	142

Symmetry codes: (i) −x+1, y−1/2, −z+1/2; (ii) x, y+1, z; (iii) −x+2, −y+1, −z+1; (iv) −x+2, y−1/2, −z+1/2; (v) x+1, −y−1/2, z+1/2; (vi) −x+2, −y, −z+1.