[(Amino)(5-amino-4-amino­carbonyl-1H-imidazol-3-ium-4-yl)methyl­ene]oxonium 5-amino-4-amino­carbonyl-1H-imidazolium sulfate hydrogen sulfate

The asymmetric unit of the title compound, C₄H₈N₄O²⁺·C₄H₇N₄O⁺·SO₄²⁻·HSO₄⁻, contains one half of an O—H...O hydrogen-bonded dimer-like unit, viz. a C₄H₈N₄O²⁺·C₄H₇N₄O⁺ unit and one half of an SO₄²⁻·HSO₄⁻ unit. Each of these dimeric units lies on an inversion centre, with the O-bound H atoms disordered across inversion centres. The cations and part of the anions are arranged in layers parallel to the (20) plane through a combination of N—H...O, N—H...S and O—H...S hydrogen bonds

Key indicators

• Single-crystal X-ray study
• T = 223 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.030
• wR factor = 0.075
• Data-to-parameter ratio = 9.2

checkCIF/PLATON results

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Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT088_ALERT_3_C Poor Data / Parameter Ratio ....................       9.24

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

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

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 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

The chemistry of imidazole compounds has been of much interest due to the presence of such heterocycle in a large variety of biologically important molecules. For example, some imidazole derivatives have shown interesting antifungal and antitumour properties (Sandbhor et al., 2004). In living systems, the imidazole ring is an essential metal bingding site, since imidazole units are bound to metal ions in almost all copper- and zinc-metalloproteins and in nickel-containing urease (Materazzi et al., 2004). A component of the title compound, 5-amino-1H-imidazole-4-carboxamide, is useful as an important intermediate in preparing guanine and xanthine,which are themselves useful for the preparation of pharmacueticals (Asai, 1974). Also, it useful as an additive in the fermentation of microorganisms, and used in the treatment of liver function disorders. We report here the crystal structure of the title compound.

The asymmetric unit of the title compound contains one half each of O—H···O hydrogen-bonded C₄H₈N₄O²⁺·C₄H₇N₄O⁺ cationic units, and SO₄^2-·HSO₄^- anionic units. Each of these hydrogen-bonded dimer-like units lie on inversion centres (Fig. 1). The O-bound H atoms of these units are disordered across the inversion centres. The imidazolium ring is planar to within ±0.003 (1) Å. The amino and carboxamide groups are coplanar with the imidazolium ring, with atoms N4 and O1 deviating from the imidazolium plane by 0.018 (3) Å and 0.039 (3) Å, respectively. The C4═ O1 bond length of 1.283 (2) Å is significantly longer compared to the corresponding distance (1.230 (3)–1.255 (4) Å) observed in structures containing oxonium ion (Banerjee et al., 1991, 1999; Adamiak et al., 1979; Dey et al., 2006). The geometric parameters of the sulfate anion are consistent with the reported data (Hemamalini et al., 2005; Huo et al., 2005). The O—S—O bond angles (Table 1) of the sulfate group, in the range 105.36 (8)–112.17 (8)°, indicate a distorted tetrahedron.

The cationic units and part of the anionic units are arranged in layers parallel to the (1 2 0) plane through a combination of N—H···O, N—H···S and O—H···S hydrogen bonds (Table 2).

Related literature

For the synthesis, see: Asai (1974). For general background, see: Sandbhor et al. (2004); Materazzi et al. (2004). For related structures, see: Banerjee et al. (1991, 1999); Adamiak et al. (1979); Dey et al. (2006); Hemamalini et al. (2005); Huo et al. (2005).

S2. Experimental

The title compound was prepared according to the literature method (Asai, 1974). Crystals suitable for X-ray analysis were obtained by slow evaporation of an ethanol solution at room temperature (m.p. 443–445 K).

S3. Refinement

All H atoms were located in a difference map. Atoms H1O and H4O are disordered across inversion centres and they were refined with site occupancies of 0.50. The O4—H4O distance was restrained to 0.85 (3) Å. Atom H3 was included in the riding model approximation, with C—H = 0.94 Å and U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: CrystalClear (Rigaku, 2001); cell refinement: CrystalClear (Rigaku, 2001); data reduction: CrystalStructure (Rigaku/MSC, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1998); software used to prepare material for publication: SHELXTL (Bruker, 1998).

Figures

Fig. 1. The asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 20% probability level. Unlabelled atoms are related to other labelled atoms by the symmetry operation (2 - x, 1 - y, 1 - z) in cationic units and (-x, 1 - y, -z) in anionic units. Hydrogen bonds are shown as dashed lines.

[(Amino)(5-amino-4-aminocarbonyl-1H-imidazol-3-ium-4-yl)methylene]oxonium 5-amino-4-aminocarbonyl-1H-imidazolium sulfate hydrogen sulfate

Crystal data

C4H8N4O^2+·C4H7N4O^+·SO4^2^−·HSO4^−	Z = 1
Mr = 448.41	F(000) = 232
Triclinic, P1	Dx = 1.832 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71070 Å
a = 6.0731 (16) Å	Cell parameters from 3859 reflections
b = 7.929 (3) Å	θ = 3.4–25.3°
c = 9.257 (3) Å	µ = 0.41 mm^−1
α = 113.841 (6)°	T = 223 K
β = 92.660 (5)°	Block, colourless
γ = 92.220 (5)°	0.50 × 0.45 × 0.23 mm
V = 406.5 (2) Å^3

Data collection

Rigaku Mercury diffractometer	1469 independent reflections
Radiation source: fine-focus sealed tube	1376 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.017
Detector resolution: 7.31 pixels mm^-1	θmax = 25.3°, θmin = 3.4°
ω scans	h = −7→7
Absorption correction: multi-scan (Jacobson, 1998)	k = −9→8
Tmin = 0.823, Tmax = 0.913	l = −11→11
3859 measured reflections

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)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.075	H atoms treated by a mixture of independent and constrained refinement
S = 1.10	w = 1/[σ^2(Fo^2) + (0.0351P)^2 + 0.2509P] where P = (Fo^2 + 2Fc^2)/3
1469 reflections	(Δ/σ)max = 0.001
159 parameters	Δρmax = 0.25 e Å^−3
1 restraint	Δρmin = −0.40 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	Occ. (<1)
O1	0.8662 (2)	0.59705 (19)	0.58585 (16)	0.0255 (3)
H1O	0.959 (10)	0.536 (8)	0.525 (8)	0.047 (17)*	0.50
N1	0.3241 (3)	0.8526 (2)	0.82081 (19)	0.0223 (4)
H1	0.256 (4)	0.864 (4)	0.902 (3)	0.048 (8)*
N2	0.3694 (2)	0.8362 (2)	0.58551 (19)	0.0195 (3)
H2	0.335 (4)	0.848 (3)	0.499 (3)	0.031 (6)*
N3	0.7272 (3)	0.6588 (2)	0.38140 (19)	0.0222 (4)
H3A	0.617 (4)	0.695 (3)	0.337 (3)	0.036 (6)*
H3B	0.841 (4)	0.616 (3)	0.328 (3)	0.031 (6)*
N4	0.6298 (3)	0.7035 (2)	0.8699 (2)	0.0266 (4)
H4A	0.743 (4)	0.642 (3)	0.831 (3)	0.037 (7)*
H4B	0.574 (4)	0.709 (3)	0.957 (3)	0.037 (6)*
C1	0.5441 (3)	0.7481 (2)	0.6234 (2)	0.0175 (4)
C2	0.5134 (3)	0.7603 (2)	0.7755 (2)	0.0180 (4)
C3	0.2418 (3)	0.8952 (3)	0.7039 (2)	0.0224 (4)
H3	0.1126	0.9577	0.7065	0.027*
C4	0.7185 (3)	0.6652 (2)	0.5253 (2)	0.0185 (4)
S1	0.20015 (7)	0.76780 (6)	0.17903 (5)	0.01807 (16)
O2	0.4304 (2)	0.72426 (19)	0.15779 (16)	0.0276 (3)
O3	0.1683 (2)	0.88383 (18)	0.34502 (14)	0.0238 (3)
O4	0.0598 (2)	0.58928 (18)	0.14092 (16)	0.0250 (3)
H4O	0.037 (11)	0.528 (9)	0.045 (4)	0.057 (18)*	0.50
O5	0.1189 (2)	0.85258 (19)	0.07560 (15)	0.0265 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0224 (7)	0.0334 (8)	0.0223 (7)	0.0122 (6)	0.0052 (6)	0.0118 (6)
N1	0.0227 (8)	0.0243 (8)	0.0206 (8)	0.0060 (6)	0.0085 (7)	0.0088 (7)
N2	0.0203 (8)	0.0213 (8)	0.0186 (8)	0.0042 (6)	0.0014 (6)	0.0096 (6)
N3	0.0194 (8)	0.0293 (9)	0.0204 (8)	0.0057 (7)	0.0068 (7)	0.0119 (7)
N4	0.0301 (9)	0.0341 (10)	0.0205 (9)	0.0121 (8)	0.0068 (7)	0.0148 (8)
C1	0.0171 (9)	0.0183 (9)	0.0184 (9)	0.0026 (7)	0.0017 (7)	0.0087 (7)
C2	0.0187 (8)	0.0158 (8)	0.0190 (9)	0.0008 (7)	0.0025 (7)	0.0065 (7)
C3	0.0205 (9)	0.0217 (9)	0.0245 (10)	0.0055 (7)	0.0042 (8)	0.0082 (8)
C4	0.0179 (9)	0.0170 (9)	0.0196 (9)	−0.0010 (7)	0.0015 (7)	0.0067 (7)
S1	0.0193 (3)	0.0215 (3)	0.0153 (2)	0.00434 (18)	0.00328 (17)	0.00899 (19)
O2	0.0208 (7)	0.0379 (8)	0.0298 (8)	0.0085 (6)	0.0068 (6)	0.0185 (6)
O3	0.0313 (7)	0.0239 (7)	0.0155 (6)	0.0060 (6)	0.0030 (5)	0.0066 (5)
O4	0.0301 (7)	0.0245 (7)	0.0190 (7)	−0.0029 (6)	0.0026 (6)	0.0077 (6)
O5	0.0293 (7)	0.0357 (8)	0.0234 (7)	0.0101 (6)	0.0068 (6)	0.0199 (6)

Geometric parameters (Å, º)

O1—C4	1.283 (2)	N4—C2	1.324 (2)
O1—H1O	0.84 (5)	N4—H4A	0.87 (3)
N1—C3	1.339 (3)	N4—H4B	0.87 (3)
N1—C2	1.377 (2)	C1—C2	1.393 (2)
N1—H1	0.85 (3)	C1—C4	1.429 (2)
N2—C3	1.309 (2)	C3—H3	0.94
N2—C1	1.399 (2)	S1—O5	1.4540 (13)
N2—H2	0.86 (2)	S1—O2	1.4568 (14)
N3—C4	1.316 (2)	S1—O3	1.4641 (13)
N3—H3A	0.88 (3)	S1—O4	1.5263 (15)
N3—H3B	0.86 (3)	O4—H4O	0.83 (3)
C4—O1—H1O	116 (5)	N4—C2—N1	121.98 (17)
C3—N1—C2	109.38 (16)	N4—C2—C1	131.95 (17)
C3—N1—H1	123.9 (18)	N1—C2—C1	106.07 (15)
C2—N1—H1	125.9 (18)	N2—C3—N1	109.33 (16)
C3—N2—C1	109.21 (16)	N2—C3—H3	125.3
C3—N2—H2	120.8 (16)	N1—C3—H3	125.3
C1—N2—H2	129.8 (16)	O1—C4—N3	121.99 (17)
C4—N3—H3A	121.1 (16)	O1—C4—C1	115.94 (16)
C4—N3—H3B	119.6 (15)	N3—C4—C1	122.07 (17)
H3A—N3—H3B	119 (2)	O5—S1—O2	112.17 (8)
C2—N4—H4A	116.3 (16)	O5—S1—O3	111.19 (8)
C2—N4—H4B	118.8 (16)	O2—S1—O3	110.78 (8)
H4A—N4—H4B	124 (2)	O5—S1—O4	108.28 (8)
C2—C1—N2	106.00 (15)	O2—S1—O4	108.77 (8)
C2—C1—C4	127.66 (16)	O3—S1—O4	105.36 (8)
N2—C1—C4	126.34 (16)	S1—O4—H4O	112 (5)
C3—N2—C1—C2	−0.6 (2)	C4—C1—C2—N1	179.67 (17)
C3—N2—C1—C4	−179.96 (17)	C1—N2—C3—N1	0.7 (2)
C3—N1—C2—N4	179.34 (17)	C2—N1—C3—N2	−0.4 (2)
C3—N1—C2—C1	0.0 (2)	C2—C1—C4—O1	−1.4 (3)
N2—C1—C2—N4	−178.85 (19)	N2—C1—C4—O1	177.80 (16)
C4—C1—C2—N4	0.5 (3)	C2—C1—C4—N3	178.53 (17)
N2—C1—C2—N1	0.35 (19)	N2—C1—C4—N3	−2.3 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O5^i	0.85 (3)	1.87 (3)	2.718 (2)	171 (3)
N2—H2···O3	0.86 (2)	1.83 (2)	2.656 (2)	160 (2)
N2—H2···S1	0.86 (2)	2.84 (2)	3.668 (2)	162 (2)
N3—H3B···O4^ii	0.86 (3)	2.18 (3)	2.975 (2)	152 (2)
N3—H3A···O2	0.88 (3)	2.06 (3)	2.898 (2)	157 (2)
N4—H4B···O2^i	0.87 (3)	2.05 (3)	2.925 (2)	178 (2)
N4—H4A···O4^iii	0.87 (3)	2.32 (3)	3.020 (2)	138 (2)
N4—H4A···O1	0.87 (3)	2.31 (3)	2.888 (2)	124 (2)
O1—H1O···O1^iv	0.84 (5)	1.61 (5)	2.448 (3)	174 (7)
O4—H4O···O4^v	0.83 (3)	1.65 (3)	2.469 (3)	169 (7)
O4—H4O···S1^v	0.83 (3)	2.72 (5)	3.424 (2)	144 (6)

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