2-Amino­benzimidazolium hydrogen sulfate

Abstract

In the title salt, C₇H₈N₃ ⁺·HSO₄ ⁻, the benzimdazole ring system is planar [mean deviation 0.0086 (1) Å]. In the crystal, N—H⋯O and O—H⋯O hydrogen-bond inter­actions give rise to a layer motif.

Related literature

For related compounds, see: El-Medania et al. (2003 ▶); Yeşilel et al. (2008 ▶).

Experimental

Crystal data

• C₇H₈N₃ ⁺·HSO₄ ⁻

• M _r = 231.23

• Monoclinic,

• a = 10.855 (6) Å

• b = 13.049 (7) Å

• c = 7.082 (4) Å

• β = 99.025 (7)°

• V = 990.7 (9) ų

• Z = 4

• Mo Kα radiation

• μ = 0.33 mm⁻¹

• T = 291 (2) K

• 0.16 × 0.12 × 0.10 mm

Data collection

• Bruker SMART diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2000 ▶) T _min = 0.950, T _max = 0.968

• 5083 measured reflections

• 1841 independent reflections

• 1408 reflections with I > 2σ(I)

• R _int = 0.057

Refinement

• R[F ² > 2σ(F ²)] = 0.038

• wR(F ²) = 0.103

• S = 0.96

• 1841 reflections

• 136 parameters

• H-atom parameters constrained

• Δρ_max = 0.23 e Å⁻³

• Δρ_min = −0.35 e Å⁻³

Data collection: SMART (Bruker, 2000 ▶); cell refinement: SAINT (Bruker, 2000 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

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—H1A⋯O4i	0.86	2.00	2.848 (3)	167
O1—H1B⋯O2ii	0.82	1.80	2.619 (2)	176
N2—H2A⋯O3	0.86	1.94	2.795 (2)	177
N3—H3A⋯O3i	0.86	2.09	2.899 (3)	157
N3—H3B⋯O2	0.86	2.17	2.987 (2)	158

Symmetry codes: (i) ; (ii) .

supplementary crystallographic information

Comment

Several ion-pair adducts of 2-aminobenzimidazole with different organic acids such as picric acid (El-Medania et al., 2003) and squaric acid (YeŞilel et al., 2008) have been reported. Herein, we present a hydrogen sulfate of 2-aminobenzimidazole.

The atom-numbering scheme of the title compound is shown in Fig. 1, while selected bond distances and bond angles are given in Table 1. The benzimidazole skeleton of the title compound is planar and the proton is delocalized within the imidazole ring although it is added to one of the nitrogen atoms. With regard to the hydrogen sulfate anion, the hydrogen atom is added to the O1 atom of SO₄ group due to the obviously longer O1–S1 bond length. In the crystal packing, typical π-π stacking can be found between neighbouring aromatic rings with the centroid-to-centroid separation of 3.452 (2) Å. Furthermore, N—H···O and O—H···O hydrogen bonding interactions are found between adjacent molecules to form a three-dimensional network (Fig. 2).

Experimental

The treatment of 2-aminobenzimidazole dissolved in methanol with an excess of hydrochloric acid yields the title compound. Single crystal suitable for X-ray diffraction measurement was obtained after 3 days' slow evaporation of the mother liquid at room temperature in air. Anal. Calcd. For C~7~H~9Ñ~3Õ~4~S: C, 36.36; H, 3.92; O, 27.68%. Found: C, 36.17; H, 4.03; N, 27.74%. Main FT—IR absorptions (KBr pellets, cm^-1): 3385 (s), 3194 (m), 1687 (s), 1476 (m), 1286 (m), 1206(s), 1175 (vs), 1070 (m), 1026 (m), 888 (s), and 577 (w).

Refinement

The non-hydrogen atoms were refined anisotropically, whereas the H atoms bonded with carbon, nitrogen and oxygen atoms were placed in geometrically idealized positions (C—H = 0.93 Å, N—H = 0.86 Å and O—H = 0.82 Å) and refined as riding atoms, with U_iso(H) = 1.2U_eq(C) and 1.2U~eq~(N) and Uĩso~(H) = 1.5U~eq~(O).

Figures

Fig. 1.

An ORTEP drawing of the title compound with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.

Fig. 2.

A perspective view of the packing structure of the title compound. Symmetry codes: (i) -x + 1, y - 1/2, -z + 1/2; (ii) x, -y + 3/2, z + 1/2.

Crystal data

C7H8N3+·HSO4−	F(000) = 480
Mr = 231.23	Dx = 1.550 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1841 reflections
a = 10.855 (6) Å	θ = 1.0–1.0°
b = 13.049 (7) Å	µ = 0.33 mm−1
c = 7.082 (4) Å	T = 291 K
β = 99.025 (7)°	Block, colourless
V = 990.7 (9) Å3	0.16 × 0.12 × 0.10 mm
Z = 4

Data collection

Bruker SMART diffractometer	1841 independent reflections
Radiation source: fine-focus sealed tube	1408 reflections with I > 2σ(I)
graphite	Rint = 0.057
φ and ω scans	θmax = 25.5°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −13→13
Tmin = 0.950, Tmax = 0.968	k = −11→15
5083 measured reflections	l = −8→8

Refinement

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.038	H-atom parameters constrained
wR(F2) = 0.103	w = 1/[σ2(Fo2) + (0.0593P)2] where P = (Fo2 + 2Fc2)/3
S = 0.96	(Δ/σ)max = 0.001
1841 reflections	Δρmax = 0.23 e Å−3
136 parameters	Δρmin = −0.35 e Å−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008)
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0

Special details

Experimental. The structure was solved by direct methods (Bruker, 2000) and successive difference Fourier syntheses.

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
C1	0.61393 (19)	0.67017 (16)	0.3926 (3)	0.0400 (5)
C2	0.80252 (18)	0.71967 (16)	0.5357 (3)	0.0387 (5)
C3	0.9247 (2)	0.72581 (18)	0.6229 (3)	0.0483 (6)
H3	0.9725	0.6674	0.6557	0.058*
C4	0.9730 (2)	0.82273 (19)	0.6594 (3)	0.0533 (6)
H4	1.0555	0.8296	0.7178	0.064*
C5	0.9026 (2)	0.91056 (19)	0.6120 (3)	0.0563 (6)
H5	0.9382	0.9746	0.6407	0.068*
C6	0.7787 (2)	0.90386 (17)	0.5216 (3)	0.0497 (6)
H6	0.7310	0.9620	0.4866	0.060*
C7	0.73133 (18)	0.80702 (16)	0.4872 (3)	0.0385 (5)
N1	0.72523 (15)	0.63593 (13)	0.4769 (2)	0.0410 (4)
H1A	0.7460	0.5725	0.4925	0.049*
N2	0.61415 (15)	0.77282 (13)	0.3989 (2)	0.0429 (5)
H2A	0.5521	0.8116	0.3555	0.051*
N3	0.51968 (16)	0.61327 (14)	0.3154 (3)	0.0534 (5)
H3A	0.5265	0.5476	0.3163	0.064*
H3B	0.4511	0.6416	0.2639	0.064*
O1	0.21109 (12)	0.84704 (11)	0.3128 (2)	0.0508 (4)
H1B	0.2450	0.8155	0.4069	0.076*
O2	0.32882 (14)	0.75437 (11)	0.1058 (2)	0.0533 (5)
O3	0.41587 (12)	0.90419 (10)	0.2672 (2)	0.0494 (4)
O4	0.23730 (14)	0.91989 (11)	0.0168 (2)	0.0539 (4)
S1	0.30277 (5)	0.85757 (4)	0.16657 (8)	0.0404 (2)

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
C1	0.0399 (11)	0.0385 (12)	0.0414 (12)	0.0044 (9)	0.0057 (10)	−0.0029 (9)
C2	0.0419 (12)	0.0400 (12)	0.0344 (11)	0.0037 (9)	0.0069 (9)	−0.0013 (9)
C3	0.0444 (12)	0.0581 (15)	0.0420 (13)	0.0089 (11)	0.0057 (10)	0.0033 (11)
C4	0.0416 (13)	0.0658 (17)	0.0518 (15)	−0.0066 (11)	0.0051 (11)	−0.0039 (12)
C5	0.0584 (15)	0.0548 (16)	0.0577 (15)	−0.0130 (12)	0.0151 (12)	−0.0092 (12)
C6	0.0537 (14)	0.0407 (13)	0.0552 (15)	0.0009 (10)	0.0103 (12)	−0.0020 (11)
C7	0.0401 (11)	0.0386 (12)	0.0371 (12)	0.0045 (9)	0.0073 (9)	−0.0016 (9)
N1	0.0438 (10)	0.0322 (10)	0.0453 (11)	0.0091 (7)	0.0017 (8)	−0.0001 (7)
N2	0.0404 (10)	0.0343 (10)	0.0520 (12)	0.0109 (7)	0.0013 (8)	−0.0010 (8)
N3	0.0447 (10)	0.0400 (11)	0.0719 (14)	0.0050 (8)	−0.0019 (10)	−0.0067 (10)
O1	0.0408 (8)	0.0495 (10)	0.0611 (10)	0.0055 (7)	0.0047 (8)	0.0063 (7)
O2	0.0640 (10)	0.0331 (9)	0.0582 (10)	0.0091 (7)	−0.0047 (8)	−0.0073 (7)
O3	0.0387 (8)	0.0372 (9)	0.0669 (10)	−0.0035 (6)	−0.0086 (7)	0.0032 (7)
O4	0.0609 (9)	0.0381 (9)	0.0548 (10)	0.0046 (7)	−0.0153 (8)	0.0072 (7)
S1	0.0402 (3)	0.0288 (3)	0.0484 (4)	0.0019 (2)	−0.0045 (2)	0.0007 (2)

Geometric parameters (Å, °)

C1—N3	1.312 (3)	C6—C7	1.372 (3)
C1—N1	1.338 (2)	C6—H6	0.9300
C1—N2	1.340 (3)	C7—N2	1.400 (2)
C2—C3	1.375 (3)	N1—H1A	0.8600
C2—C7	1.390 (3)	N2—H2A	0.8600
C2—N1	1.401 (3)	N3—H3A	0.8600
C3—C4	1.378 (3)	N3—H3B	0.8600
C3—H3	0.9300	O1—S1	1.5510 (18)
C4—C5	1.389 (3)	O1—H1B	0.8200
C4—H4	0.9300	O2—S1	1.4549 (16)
C5—C6	1.398 (3)	O3—S1	1.4528 (14)
C5—H5	0.9300	O4—S1	1.4336 (15)
N3—C1—N1	126.0 (2)	C6—C7—N2	131.49 (19)
N3—C1—N2	125.21 (19)	C2—C7—N2	106.26 (18)
N1—C1—N2	108.79 (18)	C1—N1—C2	109.21 (17)
C3—C2—C7	121.5 (2)	C1—N1—H1A	125.4
C3—C2—N1	132.04 (19)	C2—N1—H1A	125.4
C7—C2—N1	106.42 (17)	C1—N2—C7	109.28 (16)
C2—C3—C4	116.7 (2)	C1—N2—H2A	125.4
C2—C3—H3	121.7	C7—N2—H2A	125.4
C4—C3—H3	121.7	C1—N3—H3A	120.0
C3—C4—C5	122.2 (2)	C1—N3—H3B	120.0
C3—C4—H4	118.9	H3A—N3—H3B	120.0
C5—C4—H4	118.9	S1—O1—H1B	109.5
C4—C5—C6	120.8 (2)	O4—S1—O3	114.09 (9)
C4—C5—H5	119.6	O4—S1—O2	113.76 (10)
C6—C5—H5	119.6	O3—S1—O2	110.13 (9)
C7—C6—C5	116.5 (2)	O4—S1—O1	104.41 (10)
C7—C6—H6	121.8	O3—S1—O1	106.91 (10)
C5—C6—H6	121.8	O2—S1—O1	106.88 (10)
C6—C7—C2	122.2 (2)

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O4i	0.86	2.00	2.848 (3)	167
O1—H1B···O2ii	0.82	1.80	2.619 (2)	176
N2—H2A···O3	0.86	1.94	2.795 (2)	177
N3—H3A···O3i	0.86	2.09	2.899 (3)	157
N3—H3B···O2	0.86	2.17	2.987 (2)	158

Symmetry codes: (i) −x+1, y−1/2, −z+1/2; (ii) x, −y+3/2, z+1/2.