Bis(2-amino­benzimidazolium) sulfate monohydrate

The components of the title mol­ecular salt are linked by N—H⋯O and O—H⋯O hydrogen bonds.

Abstract

In the title hydrated mol­ecular salt, 2C₇H₈N₃ ⁺·SO₄ ²⁻·H₂O, the components are linked by numerous N—H⋯O and O—H⋯O hydrogen bonds.

Structure description

2-Amino­benzimidazole has been used for the synthesis of a series of sulfur heterocycles such as 9H-3-thia-1,4a,9-tri­aza-fluorene-2,4-di­thione (1): its potassium thiol­ate salt was used to prepare metal coordination compounds (Peña-Hueso et al., 2008 ▸), and is the precursor of the title compound. When compound 1 is dissolved in dimethyl sulfoxide and strong acids are added, instead of producing the protonated derivative, the thia­diazine ring breaks down, producing 2-amino­benzimidazolium sulfate (2): its crystal structural features are the subject of the present paper.

Compound 2 is formed by the transfer of two protons from sulfuric acid to the heterocycle: the crystal has two 2-amino­benzimidazolium cations, one sulfate anion and one water mol­ecule in its asymmetric unit (Fig. 1 ▸). There is a small asymmetry in the S—O bond lengths of the SO₄ ^2– ion from 1.4596 (16) to 1.4723 (15) Å, probably caused by the hydrogen bonds around the anion (Gagné & Hawthorne, 2018 ▸). Two benzimidazolium cations are stacked in a head-to-tail way, with a distance between C9 of one mol­ecule and C18 of another of 3.441 (3) Å.

Figure 1.

The mol­ecular structure of 2 showing displacement ellipsoids drawn at the 50% probability level

The sulfate ion accepts seven N—H⋯O hydrogen bonds from four adjacent benzimidazolium cations and one O—H⋯O link from a water mol­ecule (Table 1 ▸, Fig. 2 ▸). The water mol­ecule accepts one N—H⋯O hydrogen bond and forms two O—H⋯O links to two SO₄ ^2– ions (Fig. 3 ▸). In the extended structure, the benzimidazolium cations form parallel ribbons propagating in the [010] direction (Fig. 4 ▸).

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O25i	0.81 (4)	2.25 (3)	2.946 (3)	144 (3)
N3—H3⋯O22ii	0.83 (3)	1.93 (3)	2.749 (3)	172 (3)
N11—H11⋯O23	0.85 (4)	1.96 (4)	2.786 (4)	166 (3)
N13—H13⋯O24iii	0.83 (4)	1.91 (4)	2.720 (3)	165 (3)
N10—H101⋯O23i	0.87 (4)	2.03 (4)	2.894 (5)	169 (3)
N10—H102⋯O25ii	0.89 (3)	2.00 (3)	2.890 (3)	175 (3)
N20—H201⋯O26iii	0.84 (3)	2.04 (3)	2.853 (4)	165 (3)
N20—H202⋯O22iii	0.93 (4)	2.09 (4)	2.973 (4)	157 (3)
O26—H261⋯O24iv	0.80 (7)	2.22 (7)	2.983 (4)	160 (7)
O26—H262⋯O24v	0.80 (7)	2.14 (7)	2.860 (4)	150 (6)
C17—H17⋯O22	0.95	2.56	3.272 (3)	132

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) ; (v) .

Figure 2.

Hydrogen-bond environment around the sulfate anion.

Figure 3.

Network of hydrogen bonds (dashed lines) involving the water mol­ecules and sulfate ions.

Figure 4.

The unit-cell packing showing [010] ribbons of cations linked by sulfate anions.

The first crystal structure of a 2-amino­benzimidazolium salt was reported with the nitrate anion (Bats et al., 1999 ▸) and a related structure with hydrogen sulfate as the counter-ion is also known (You et al., 2009 ▸).

Synthesis and crystallization

The decomposition of 9H-3-thia-1,4a,9-tri­aza-fluorene-2,4-di­thione with dilute aqueous H₂SO₄ in DMSO afforded the title compound 2, m.p. 287–289°C. IR (KBr), ν (cm⁻¹): 3285 (N—H), 1682 (C=N), 1520 (C=C), 1478 (C—N). NMR (DMSO-d ₆, p.p.m.) δ ¹H: 7.27 (H4, H7); 7.09 (H5, H6); 13.18 (N1—H, N3—H); 8.70 (NH₂). δ ¹³C: 152.1 (C2); 111.8 (C4, C7); 123.4 (C5, C6); 130.4 (C8, C9). δ ¹⁵N: −257.1 (N1, N3); −312.9 (N10). Analysis calculated (%) for C₁₆H₁₆N₆SO₅: C, 43.97; H, 4.74; N, 21.98. Found: C, 43.50; H, 4.80; N, 21.80. The chemical shifts of C2 (152.1 p.p.m.), C8 and C9 (130.4 p.p.m.) in the ¹³C NMR spectrum indicate that the endocyclic nitro­gen atoms are protonated, in agreement with the crystal structure.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸.

Table 2. Experimental details.

Crystal data
Chemical formula	2C7H8N3 +·SO4 2−·H2O
M r	382.4
Crystal system, space group	Monoclinic, P21/c
Temperature (K)	293
a, b, c (Å)	12.1115 (2), 10.6282 (2), 17.4772 (3)
β (°)	127.723 (1)
V (Å3)	1779.48 (6)
Z	4
Radiation type	Mo Kα
μ (mm−1)	0.22
Crystal size (mm)	0.25 × 0.25 × 0.17
Data collection
Diffractometer	Nonius KappaCCD
No. of measured, independent and observed [I > 3.0σ(I)] reflections	9132, 4563, 2429
R int	0.04
(sin θ/λ)max (Å−1)	0.675
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.041, 0.050, 1.03
No. of reflections	2429
No. of parameters	265
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)	0.25, −0.31

Computer programs: COLLECT (Nonius, 2001 ▸), DENZO/SCALEPACK (Otwinowski & Minor, 1997 ▸), SHELXS97 (Sheldrick, 2008 ▸), CRYSTALS (Betteridge et al., 2003 ▸) and CAMERON (Watkin et al., 1996 ▸).

Supplementary Material

CCDC reference: 1810894

Additional supporting information: crystallographic information; 3D view; checkCIF report

full crystallographic data

Crystal data

2C7H8N3+·SO42−·H2O	F(000) = 800
Mr = 382.4	Dx = 1.427 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 4784 reflections
a = 12.1115 (2) Å	θ = 1–29°
b = 10.6282 (2) Å	µ = 0.22 mm−1
c = 17.4772 (3) Å	T = 293 K
β = 127.723 (1)°	Prism, colourless
V = 1779.48 (6) Å3	0.25 × 0.25 × 0.17 mm
Z = 4

Data collection

Nonius KappaCCD diffractometer	2429 reflections with I > 3.0σ(I)
Radiation source: Enraf Nonius FR590	Rint = 0.04
Graphite monochromator	θmax = 28.7°, θmin = 2.1°
Detector resolution: 9 pixels mm-1	h = −15→16
φ & ω scans	k = −14→14
9132 measured reflections	l = −23→23
4563 independent reflections

Refinement

Refinement on F	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.041	Hydrogen site location: difference Fourier map
wR(F2) = 0.050	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	Method, part 1, Chebychev polynomial, (Watkin, 1994, Prince, 1982) [weight] = 1.0/[A0*T0(x) + A1*T1(x) ··· + An-1]*Tn-1(x)] where Ai are the Chebychev coefficients listed below and x = F /Fmax Method = Robust Weighting (Prince, 1982) W = [weight] * [1-(deltaF/6*sigmaF)2]2 Ai are: 0.914 0.838 0.564 0.170 0.849E-01
2429 reflections	(Δ/σ)max = 0.0002
265 parameters	Δρmax = 0.25 e Å−3
0 restraints	Δρmin = −0.31 e Å−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.The positions of all NH and OH hydrogen atoms were refined, and all CH were placed at ideal positions.

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

	x	y	z	Uiso*/Ueq
C2	0.5660 (3)	0.1533 (2)	−0.12552 (17)	0.0484
C4	0.5449 (3)	0.1836 (2)	0.0688 (2)	0.0626
C5	0.6271 (4)	0.1200 (3)	0.1556 (2)	0.0725
C6	0.7293 (3)	0.0372 (3)	0.1756 (2)	0.0728
C7	0.7524 (3)	0.0132 (3)	0.1090 (2)	0.0682
C8	0.6705 (3)	0.0761 (2)	0.02241 (18)	0.0503
C9	0.5691 (2)	0.1616 (2)	0.00250 (16)	0.047
C12	0.9604 (2)	0.2887 (2)	0.21087 (16)	0.047
C14	0.8306 (3)	0.3839 (3)	−0.0275 (2)	0.0719
C15	0.7199 (4)	0.4642 (3)	−0.0859 (2)	0.0819
C16	0.6467 (4)	0.5164 (3)	−0.0557 (2)	0.0786
C17	0.6837 (3)	0.4930 (3)	0.03457 (18)	0.0617
C18	0.7951 (2)	0.4131 (2)	0.09334 (16)	0.0479
C19	0.8659 (3)	0.3583 (2)	0.06268 (17)	0.0521
H1	0.700 (3)	0.023 (3)	−0.073 (2)	0.0781*
H3	0.440 (3)	0.256 (3)	−0.122 (2)	0.0603*
H4	0.476	0.2396	0.0553	0.0818*
H5	0.6134	0.1333	0.2013	0.0945*
H6	0.7819	−0.0041	0.2343	0.0851*
H7	0.82	−0.0425	0.1215	0.0843*
H11	0.830 (3)	0.384 (3)	0.220 (2)	0.0595*
H13	1.021 (3)	0.235 (3)	0.136 (2)	0.0682*
H14	0.8797	0.3482	−0.0463	0.0925*
H15	0.6943	0.4849	−0.1462	0.0986*
H16	0.5679	0.568	−0.0992	0.0857*
H17	0.6367	0.5309	0.0569	0.0697*
H101	0.580 (3)	0.137 (3)	−0.227 (2)	0.0811*
H102	0.472 (3)	0.237 (3)	−0.247 (2)	0.0806*
H201	1.041 (3)	0.247 (3)	0.339 (2)	0.07*
H202	1.115 (3)	0.183 (3)	0.301 (2)	0.0698*
H261	0.979 (7)	0.918 (6)	0.069 (5)	0.1811*
H262	0.925 (6)	0.838 (6)	0.005 (5)	0.1804*
N1	0.6657 (2)	0.0745 (2)	−0.05947 (16)	0.0562
N3	0.5078 (2)	0.20819 (19)	−0.08953 (14)	0.0477
N10	0.5301 (3)	0.1737 (2)	−0.21296 (17)	0.0601
N11	0.85749 (19)	0.3685 (2)	0.18649 (14)	0.0479
N13	0.9688 (2)	0.2826 (2)	0.13810 (14)	0.0539
N20	1.0417 (2)	0.2263 (2)	0.29315 (16)	0.0582
O22	0.72767 (16)	0.64914 (16)	0.21275 (11)	0.0506
O23	0.72874 (19)	0.44104 (15)	0.26788 (13)	0.0584
O24	0.8960 (2)	0.5933 (2)	0.37860 (12)	0.0746
O25	0.6554 (2)	0.61476 (17)	0.31313 (14)	0.0657
O26	0.9603 (4)	0.8443 (3)	0.06107 (18)	0.1136
S21	0.75054 (6)	0.57563 (5)	0.29273 (4)	0.0431

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
C2	0.0604 (14)	0.0435 (12)	0.0537 (13)	0.0027 (10)	0.0411 (12)	−0.0021 (10)
C4	0.0850 (19)	0.0550 (15)	0.0668 (16)	0.0109 (13)	0.0563 (16)	0.0013 (12)
C5	0.109 (2)	0.0657 (17)	0.0641 (17)	0.0001 (17)	0.0640 (18)	0.0001 (14)
C6	0.087 (2)	0.0733 (18)	0.0555 (15)	0.0049 (16)	0.0420 (16)	0.0142 (14)
C7	0.0703 (17)	0.0651 (17)	0.0705 (17)	0.0194 (14)	0.0436 (15)	0.0185 (14)
C8	0.0577 (14)	0.0464 (12)	0.0551 (14)	0.0060 (11)	0.0388 (12)	0.0017 (11)
C9	0.0580 (13)	0.0411 (11)	0.0484 (12)	0.0015 (10)	0.0358 (11)	−0.0010 (10)
C12	0.0421 (11)	0.0541 (13)	0.0449 (12)	−0.0005 (10)	0.0266 (11)	−0.0062 (11)
C14	0.086 (2)	0.087 (2)	0.0555 (16)	0.0163 (16)	0.0498 (16)	−0.0027 (14)
C15	0.107 (3)	0.085 (2)	0.0498 (15)	0.0272 (19)	0.0461 (17)	0.0063 (14)
C16	0.090 (2)	0.0757 (19)	0.0485 (15)	0.0291 (17)	0.0315 (15)	−0.0001 (14)
C17	0.0615 (15)	0.0649 (16)	0.0475 (14)	0.0171 (13)	0.0277 (12)	−0.0065 (12)
C18	0.0467 (12)	0.0520 (13)	0.0425 (12)	0.0014 (10)	0.0261 (11)	−0.0085 (10)
C19	0.0542 (14)	0.0561 (14)	0.0480 (13)	0.0051 (11)	0.0322 (12)	−0.0054 (11)
N1	0.0716 (14)	0.0522 (12)	0.0658 (13)	0.0182 (11)	0.0527 (12)	0.0089 (10)
N3	0.0555 (11)	0.0470 (10)	0.0480 (11)	0.0102 (9)	0.0356 (10)	0.0018 (9)
N10	0.0807 (16)	0.0608 (13)	0.0583 (13)	0.0140 (11)	0.0525 (13)	0.0042 (10)
N11	0.0440 (10)	0.0592 (12)	0.0450 (10)	0.0050 (9)	0.0296 (9)	−0.0045 (9)
N13	0.0522 (12)	0.0660 (13)	0.0499 (11)	0.0139 (10)	0.0345 (10)	−0.0004 (10)
N20	0.0551 (12)	0.0685 (14)	0.0502 (12)	0.0098 (11)	0.0318 (11)	0.0020 (11)
O22	0.0481 (9)	0.0669 (10)	0.0421 (8)	0.0040 (7)	0.0302 (8)	0.0120 (7)
O23	0.0752 (12)	0.0507 (9)	0.0791 (12)	−0.0031 (8)	0.0624 (11)	−0.0046 (8)
O24	0.0619 (11)	0.1028 (15)	0.0410 (9)	−0.0251 (11)	0.0223 (9)	0.0111 (9)
O25	0.0948 (14)	0.0562 (10)	0.0907 (13)	0.0093 (9)	0.0796 (12)	0.0092 (9)
O26	0.144 (2)	0.148 (3)	0.0652 (14)	−0.069 (2)	0.0725 (17)	−0.0286 (16)
S21	0.0483 (3)	0.0508 (3)	0.0396 (3)	−0.0046 (3)	0.0317 (3)	0.0008 (2)

Geometric parameters (Å, º)

C2—N1	1.336 (3)	C15—H15	0.925
C2—N3	1.333 (3)	C16—C17	1.374 (4)
C2—N10	1.326 (3)	C16—H16	0.95
C4—C5	1.380 (4)	C17—C18	1.379 (3)
C4—C9	1.377 (3)	C17—H17	0.955
C4—H4	0.931	C18—C19	1.387 (3)
C5—C6	1.379 (4)	C18—N11	1.393 (3)
C5—H5	0.92	C19—N13	1.389 (3)
C6—C7	1.378 (4)	H1—N1	0.80 (3)
C6—H6	0.922	H3—N3	0.83 (3)
C7—C8	1.373 (4)	H11—N11	0.85 (3)
C7—H7	0.921	H13—N13	0.83 (3)
C8—C9	1.390 (3)	H101—N10	0.87 (3)
C8—N1	1.396 (3)	H102—N10	0.89 (3)
C9—N3	1.386 (3)	H201—N20	0.83 (3)
C12—N11	1.343 (3)	H202—N20	0.93 (3)
C12—N13	1.338 (3)	H261—O26	0.81 (6)
C12—N20	1.321 (3)	H262—O26	0.79 (6)
C14—C15	1.376 (4)	O22—S21	1.4723 (15)
C14—C19	1.385 (4)	O23—S21	1.4711 (18)
C14—H14	0.919	O24—S21	1.4680 (19)
C15—C16	1.394 (4)	O25—S21	1.4596 (16)
N1—C2—N3	109.0 (2)	C16—C17—H17	122.5
N1—C2—N10	125.7 (2)	C18—C17—H17	120.8
N3—C2—N10	125.2 (2)	C17—C18—C19	121.7 (2)
C5—C4—C9	117.5 (2)	C17—C18—N11	131.6 (2)
C5—C4—H4	121.5	C19—C18—N11	106.7 (2)
C9—C4—H4	121	C18—C19—C14	121.6 (2)
C4—C5—C6	121.5 (3)	C18—C19—N13	106.5 (2)
C4—C5—H5	119.2	C14—C19—N13	131.8 (2)
C6—C5—H5	119.3	C8—N1—C2	109.08 (19)
C5—C6—C7	121.3 (3)	C8—N1—H1	127 (2)
C5—C6—H6	119.3	C2—N1—H1	122 (2)
C7—C6—H6	119.4	C9—N3—C2	109.2 (2)
C6—C7—C8	117.2 (3)	C9—N3—H3	128.6 (19)
C6—C7—H7	122	C2—N3—H3	121.9 (19)
C8—C7—H7	120.8	H102—N10—C2	117 (2)
C7—C8—C9	121.8 (2)	H102—N10—H101	124 (3)
C7—C8—N1	132.3 (2)	C2—N10—H101	117 (2)
C9—C8—N1	106.0 (2)	C18—N11—C12	108.65 (18)
C8—C9—C4	120.7 (2)	C18—N11—H11	125.7 (19)
C8—C9—N3	106.76 (19)	C12—N11—H11	125.5 (19)
C4—C9—N3	132.5 (2)	C19—N13—C12	109.13 (19)
N11—C12—N13	109.0 (2)	C19—N13—H13	125 (2)
N11—C12—N20	126.2 (2)	C12—N13—H13	126 (2)
N13—C12—N20	124.8 (2)	H202—N20—C12	114.7 (18)
C15—C14—C19	116.6 (2)	H202—N20—H201	124 (3)
C15—C14—H14	122.8	C12—N20—H201	118 (2)
C19—C14—H14	120.7	H261—O26—H262	100 (6)
C14—C15—C16	121.6 (3)	O22—S21—O23	109.89 (10)
C14—C15—H15	119.2	O22—S21—O24	108.29 (10)
C16—C15—H15	119.3	O23—S21—O24	108.23 (12)
C15—C16—C17	121.7 (3)	O22—S21—O25	111.26 (10)
C15—C16—H16	119.2	O23—S21—O25	108.86 (10)
C17—C16—H16	119.1	O24—S21—O25	110.26 (13)
C16—C17—C18	116.8 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O25i	0.81 (4)	2.25 (3)	2.946 (3)	144 (3)
N3—H3···O22ii	0.83 (3)	1.93 (3)	2.749 (3)	172 (3)
N11—H11···O23	0.85 (4)	1.96 (4)	2.786 (4)	166 (3)
N13—H13···O24iii	0.83 (4)	1.91 (4)	2.720 (3)	165 (3)
N10—H101···O23i	0.87 (4)	2.03 (4)	2.894 (5)	169 (3)
N10—H102···O25ii	0.89 (3)	2.00 (3)	2.890 (3)	175 (3)
N20—H201···O26iii	0.84 (3)	2.04 (3)	2.853 (4)	165 (3)
N20—H202···O22iii	0.93 (4)	2.09 (4)	2.973 (4)	157 (3)
O26—H261···O24iv	0.80 (7)	2.22 (7)	2.983 (4)	160 (7)
O26—H262···O24v	0.80 (7)	2.14 (7)	2.860 (4)	150 (6)
C17—H17···O22	0.95	2.56	3.272 (3)	132

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

Funding Statement

The authors thank Cinvestav for financial support.