2-Trifluoro­methyl-1H-benzimidazol-3-ium hydrogen sulfate

In the crystal of the title mol­ecular salt, C₈H₆F₃N₂⁺·HSO₄⁻, cation-to-anion N—H...O hydrogen bonds generate [100] chains. Anion-to-anion O—H...O hydrogen bonds generate [001] helices and cross-link the chains into a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.009 Å
• R factor = 0.052
• wR factor = 0.134
• Data-to-parameter ratio = 11.8

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Alert level C
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.08
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C1
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         S1
PLAT340_ALERT_3_C Low Bond Precision on  C-C Bonds ...............     0.0087 Ang
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          2
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          1

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           24.99
           From the CIF: _reflns_number_total               1977
           Count of symmetry unique reflns         1020
           Completeness (_total/calc)            193.82%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       957
           Fraction of Friedel pairs measured     0.938
           Are heavy atom types Z>Si present        yes
PLAT002_ALERT_2_G Number of Distance or Angle Restraints on AtSite          2
PLAT003_ALERT_2_G Number of Uiso or Uij Restrained Atom Sites ....          2
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT194_ALERT_1_G Missing _cell_measurement_reflns_used datum ....          ?
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported   _diffrn_ambient_temperature        293 K
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          8
PLAT909_ALERT_3_G Percentage of Observed Data at Theta(Max) still          90 Perc.
PLAT961_ALERT_5_G Dataset Contains no Negative Intensities .......          !

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   6 ALERT level C = Check. Ensure it is not caused by an omission or oversight
  10 ALERT level G = General information/check it is not something unexpected

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


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Alert level G
PUBL013_ALERT_1_G The _publ_section_comment (discussion of study) is
            missing. This is required for a full paper submission (but is
            optional for an electronic paper).

   0 ALERT level A = Data missing that is essential or data in wrong format
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---

Related literature

For a related structure and background to molecular salts, see: Liu (2011).

S1. Experimental

0.144 g(1 mmol) of 2-Trifluoromethl-1H-benzimidazole was firstly dissolved in 30 ml me thanol, to which 0.1 g (1 mmol) of sulfuric acid was then added to afford the solution without any precipitation under stirring at the ambient temperature. Colourless blocks of the title compound were obtained by the slow evaporation of the above solution after 2 days in air.

The dielectric constant of the compound as a function of temperature indicates that the permittivity is basically temperature-independent (ε = C/(T–T₀)), suggesting that this compound is not ferroelectric or there may be no distinct phase transition occurring within the measured temperature within the measured temperature (below the melting point).

S2. Refinement

H atoms were placed in calculated positions (N—H = 0.89 Å; C—H = 0.93Å for Csp² atoms and C—H = 0.96Å and 0.97Å for Csp³ atoms), assigned fixed U_iso values [U_iso = 1.2Ueq(Csp²) and 1.5Ueq(Csp³,N)] and allowed to ride.The H atom bonding with N was found with O—H bond distance of 0.8600Åin the difference electron density map.

Structure description

For a related structure and background to molecular salts, see: Liu (2011).

Computing details

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); 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 (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids.
	Fig. 2. A view of the packing of the title compound, stacking along the a axis. Dashed lines indicate hydrogen bonds.

2-Trifluoromethyl-1H-benzimidazol-3-ium hydrogen sulfate

Crystal data

C8H6F3N2^+·HSO4^−	F(000) = 864
Mr = 284.22	Dx = 1.681 Mg m^−3
Hexagonal, P65	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 65	θ = 3.1–27.6°
a = 9.4119 (13) Å	µ = 0.34 mm^−1
c = 21.960 (4) Å	T = 293 K
V = 1684.7 (5) Å^3	Block, colorless
Z = 6	0.20 × 0.20 × 0.20 mm

Data collection

Rigaku Mercury2 CCD diffractometer	1977 independent reflections
Radiation source: fine-focus sealed tube	1941 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.038
CCD_Profile_fitting scans	θmax = 25.0°, θmin = 3.1°
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	h = −11→11
Tmin = 0.935, Tmax = 0.935	k = −11→11
14287 measured reflections	l = −26→26

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)] = 0.052	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.134	w = 1/[σ^2(Fo^2) + (0.0593P)^2 + 1.9666P] where P = (Fo^2 + 2Fc^2)/3
S = 1.11	(Δ/σ)max < 0.001
1977 reflections	Δρmax = 0.53 e Å^−3
167 parameters	Δρmin = −0.25 e Å^−3
8 restraints	Absolute structure: Flack (1983), 957 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.03 (16)

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
S1	0.09970 (14)	0.72553 (17)	0.16867 (6)	0.0442 (3)
N1	0.4873 (5)	0.7391 (5)	0.1735 (2)	0.0418 (9)
H1A	0.3843	0.7058	0.1770	0.050*
N2	0.7169 (4)	0.7349 (5)	0.16388 (17)	0.0348 (8)
H2A	0.7835	0.6981	0.1596	0.042*
C3	0.6124 (6)	0.9017 (6)	0.1722 (2)	0.0418 (11)
C8	0.7613 (5)	0.9011 (6)	0.1675 (2)	0.0371 (10)
C4	0.6126 (7)	1.0512 (7)	0.1762 (3)	0.0508 (13)
H4	0.5152	1.0535	0.1792	0.061*
O3	−0.0637 (4)	0.6347 (5)	0.14218 (18)	0.0558 (11)
F3	0.5450 (5)	0.4034 (5)	0.1391 (3)	0.0928 (15)
C6	0.9082 (7)	1.1891 (7)	0.1712 (3)	0.0527 (13)
H6	1.0066	1.2883	0.1710	0.063*
O1	0.0866 (5)	0.8248 (5)	0.2230 (2)	0.0627 (11)
C5	0.7592 (8)	1.1907 (7)	0.1755 (3)	0.0589 (15)
H5	0.7623	1.2909	0.1780	0.071*
F1	0.3262 (5)	0.4077 (6)	0.1346 (3)	0.116 (2)
F2	0.4211 (10)	0.3991 (6)	0.2195 (2)	0.157 (3)
O4	0.1589 (5)	0.6207 (5)	0.19150 (19)	0.0571 (11)
C7	0.9120 (6)	1.0455 (7)	0.1670 (3)	0.0456 (11)
H7	1.0103	1.0448	0.1641	0.055*
C1	0.4609 (6)	0.4596 (7)	0.1670 (3)	0.0520 (13)
O2	0.2184 (6)	0.8507 (9)	0.1300 (3)	0.110 (2)
C2	0.5531 (5)	0.6434 (6)	0.1683 (2)	0.0373 (9)
H1	0.041 (10)	0.754 (9)	0.251 (3)	0.10 (3)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0252 (5)	0.0626 (9)	0.0458 (6)	0.0227 (5)	0.0080 (5)	0.0144 (6)
N1	0.0295 (19)	0.051 (2)	0.051 (2)	0.0252 (19)	−0.0012 (18)	−0.0049 (19)
N2	0.0243 (17)	0.044 (2)	0.040 (2)	0.0205 (16)	0.0009 (16)	−0.0062 (18)
C3	0.037 (2)	0.050 (3)	0.043 (3)	0.025 (2)	0.001 (2)	−0.002 (2)
C8	0.037 (2)	0.043 (3)	0.037 (2)	0.024 (2)	−0.006 (2)	−0.005 (2)
C4	0.057 (3)	0.058 (3)	0.059 (3)	0.044 (3)	−0.002 (3)	0.003 (3)
O3	0.0362 (19)	0.087 (3)	0.059 (2)	0.042 (2)	−0.0057 (16)	−0.015 (2)
F3	0.070 (2)	0.058 (2)	0.158 (4)	0.038 (2)	0.018 (3)	−0.012 (3)
C6	0.044 (3)	0.045 (3)	0.062 (3)	0.017 (2)	0.006 (3)	0.009 (3)
O1	0.056 (3)	0.048 (2)	0.079 (3)	0.022 (2)	−0.009 (2)	−0.012 (2)
C5	0.073 (4)	0.052 (3)	0.070 (4)	0.045 (3)	−0.005 (3)	0.005 (3)
F1	0.047 (2)	0.070 (3)	0.213 (6)	0.0161 (19)	−0.039 (3)	−0.044 (3)
F2	0.246 (6)	0.055 (3)	0.072 (3)	0.002 (3)	0.038 (4)	0.009 (2)
O4	0.0403 (19)	0.074 (3)	0.072 (3)	0.039 (2)	0.0007 (17)	0.007 (2)
C7	0.030 (2)	0.055 (3)	0.050 (3)	0.020 (2)	−0.002 (2)	0.003 (2)
C1	0.036 (3)	0.043 (3)	0.067 (3)	0.012 (2)	0.014 (3)	−0.001 (3)
O2	0.057 (3)	0.155 (5)	0.108 (4)	0.045 (3)	0.032 (3)	0.093 (4)
C2	0.030 (2)	0.040 (2)	0.042 (2)	0.0176 (19)	0.0001 (19)	−0.010 (2)

Geometric parameters (Å, º)

S1—O2	1.429 (5)	C4—C5	1.348 (9)
S1—O4	1.444 (4)	C4—H4	0.9300
S1—O3	1.456 (4)	F3—C1	1.304 (6)
S1—O1	1.558 (5)	C6—C7	1.373 (8)
N1—C2	1.329 (6)	C6—C5	1.414 (8)
N1—C3	1.388 (6)	C6—H6	0.9300
N1—H1A	0.8600	O1—H1	0.86 (2)
N2—C2	1.341 (6)	C5—H5	0.9300
N2—C8	1.405 (6)	F1—C1	1.317 (8)
N2—H2A	0.8600	F2—C1	1.258 (8)
C3—C8	1.407 (6)	C7—H7	0.9300
C3—C4	1.409 (7)	C1—C2	1.499 (7)
C8—C7	1.390 (7)
O2—S1—O4	111.1 (3)	C3—C4—H4	121.2
O2—S1—O3	114.0 (3)	C7—C6—C5	122.0 (5)
O4—S1—O3	113.1 (3)	C7—C6—H6	119.0
O2—S1—O1	103.0 (4)	C5—C6—H6	119.0
O4—S1—O1	108.5 (3)	S1—O1—H1	104 (7)
O3—S1—O1	106.3 (2)	C4—C5—C6	121.9 (5)
C2—N1—C3	108.6 (4)	C4—C5—H5	119.1
C2—N1—H1A	125.7	C6—C5—H5	119.1
C3—N1—H1A	125.7	C6—C7—C8	116.5 (4)
C2—N2—C8	108.5 (3)	C6—C7—H7	121.8
C2—N2—H2A	125.8	C8—C7—H7	121.8
C8—N2—H2A	125.8	F2—C1—F3	110.5 (7)
N1—C3—C8	107.2 (4)	F2—C1—F1	108.3 (6)
N1—C3—C4	132.5 (4)	F3—C1—F1	105.2 (5)
C8—C3—C4	120.3 (5)	F2—C1—C2	112.0 (5)
C7—C8—N2	132.7 (4)	F3—C1—C2	111.0 (4)
C7—C8—C3	121.9 (4)	F1—C1—C2	109.5 (5)
N2—C8—C3	105.4 (4)	N1—C2—N2	110.3 (4)
C5—C4—C3	117.5 (5)	N1—C2—C1	125.9 (4)
C5—C4—H4	121.2	N2—C2—C1	123.8 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···O3^i	0.86	1.85	2.707 (5)	173
N1—H1A···O4	0.86	1.88	2.740 (7)	174
O1—H1···O2^ii	0.86 (2)	1.86 (6)	2.608 (7)	145 (9)

Symmetry codes: (i) x+1, y, z; (ii) y−1, −x+y, z+1/6.