1H-Benzimidazole-2-carboxylic acid monohydrate

1H-Benzimidazole-2-carboxylic acid crystallizes as the mono­hydrate, C₈H₆N₂O₂·H₂O, and the organic mol­ecule exists in a zwitterionic form, viz. 1H-benzimidazolium-2-carboxyl­ate. Hydrogen bonds connect the mol­ecules of acid and water into a two-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 130 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.053
• wR factor = 0.096
• Data-to-parameter ratio = 11.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT230_ALERT_2_C Hirshfeld Test Diff for    O1     -   C10     ..       5.97 su
PLAT340_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          5

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

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

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Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2004); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Stereochemical Workstation Operation Manual (Siemens, 1989) and Mercury (Version 1.3; Bruno et al., 2002); software used to prepare material for publication: SHELXL97.

Benzimidazole-2-carboxylic acid monohydrate

Crystal data

C8H6N2O2·H2O	F(000) = 188
Mr = 180.16	Dx = 1.494 Mg m^−3
Triclinic, P1	Melting point: 442 K
a = 4.4080 (15) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.877 (3) Å	Cell parameters from 2151 reflections
c = 10.757 (3) Å	θ = 4–25°
α = 72.20 (3)°	µ = 0.12 mm^−1
β = 87.67 (3)°	T = 130 K
γ = 88.53 (3)°	Needle, colorless
V = 400.4 (2) Å^3	0.5 × 0.07 × 0.01 mm
Z = 2

Data collection

Kuma KM-4 CCD κ geometry diffractometer	724 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.080
Graphite monochromator	θmax = 25.0°, θmin = 4.6°
ω scans	h = −5→2
3051 measured reflections	k = −10→10
1407 independent reflections	l = −12→12

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)] = 0.053	Hydrogen site location: mixed
wR(F^2) = 0.096	H-atom parameters constrained
S = 0.92	w = 1/[σ^2(Fo^2) + (0.0154P)^2] where P = (Fo^2 + 2Fc^2)/3
1407 reflections	(Δ/σ)max < 0.001
119 parameters	Δρmax = 0.24 e Å^−3
0 restraints	Δρmin = −0.26 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
O1	0.4761 (5)	−0.0814 (3)	0.1734 (2)	0.0257 (7)
O2	0.6247 (5)	−0.0980 (3)	0.3755 (2)	0.0253 (7)
N1	0.0782 (6)	0.1673 (3)	0.1801 (2)	0.0204 (8)
H1	0.0660	0.1582	0.0994	0.025*
C2	0.2471 (8)	0.0857 (4)	0.2801 (3)	0.0195 (9)
N3	0.1944 (6)	0.1433 (3)	0.3801 (2)	0.0190 (8)
H3	0.2785	0.1081	0.4589	0.023*
C4	−0.1382 (8)	0.3679 (4)	0.4113 (3)	0.0238 (10)
H4	−0.0822	0.3568	0.4965	0.029*
C5	−0.3343 (8)	0.4844 (4)	0.3428 (3)	0.0258 (10)
H5	−0.4289	0.5725	0.3854	0.031*
C6	−0.4118 (8)	0.4976 (4)	0.2127 (3)	0.0242 (10)
H6	−0.5672	0.5929	0.1723	0.013 (8)*
C7	−0.2911 (7)	0.3979 (4)	0.1482 (3)	0.0217 (9)
H7	−0.3347	0.4053	0.0592	0.026*
C8	−0.0877 (7)	0.2822 (4)	0.2172 (3)	0.0197 (9)
C9	−0.0150 (8)	0.2665 (4)	0.3454 (3)	0.0183 (9)
C10	0.4689 (8)	−0.0444 (4)	0.2771 (4)	0.0237 (10)
O1W	0.0105 (5)	0.1877 (3)	−0.0678 (2)	0.0243 (7)
H2W	0.1701	0.1724	−0.1097	0.029*
H1W	−0.1368	0.1504	−0.0971	0.029*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0275 (16)	0.0363 (17)	0.0192 (14)	0.0081 (14)	−0.0080 (11)	−0.0170 (13)
O2	0.0285 (16)	0.0291 (16)	0.0196 (14)	0.0067 (14)	−0.0090 (12)	−0.0090 (12)
N1	0.0225 (18)	0.031 (2)	0.0111 (16)	0.0042 (16)	−0.0080 (14)	−0.0102 (15)
C2	0.023 (2)	0.022 (2)	0.014 (2)	0.0005 (19)	−0.0042 (17)	−0.0056 (18)
N3	0.0206 (18)	0.0243 (19)	0.0129 (16)	0.0054 (16)	−0.0068 (14)	−0.0067 (15)
C4	0.027 (2)	0.026 (2)	0.020 (2)	0.000 (2)	−0.0058 (18)	−0.0100 (18)
C5	0.026 (2)	0.027 (2)	0.026 (2)	−0.003 (2)	−0.0012 (18)	−0.0116 (19)
C6	0.024 (2)	0.025 (2)	0.025 (2)	0.007 (2)	−0.0039 (18)	−0.0096 (19)
C7	0.024 (2)	0.022 (2)	0.018 (2)	0.001 (2)	−0.0071 (17)	−0.0042 (18)
C8	0.018 (2)	0.026 (2)	0.019 (2)	−0.003 (2)	0.0010 (17)	−0.0120 (18)
C9	0.019 (2)	0.021 (2)	0.0160 (19)	0.0059 (19)	−0.0048 (16)	−0.0075 (17)
C10	0.020 (2)	0.025 (2)	0.025 (2)	−0.005 (2)	−0.0028 (18)	−0.0060 (19)
O1W	0.0232 (14)	0.0348 (16)	0.0184 (13)	−0.0005 (13)	−0.0054 (11)	−0.0128 (12)

Geometric parameters (Å, º)

O1—C10	1.254 (4)	C4—H4	0.9335
O2—C10	1.247 (4)	C5—C6	1.424 (4)
N1—C2	1.341 (4)	C5—H5	1.0868
N1—C8	1.386 (4)	C6—C7	1.367 (4)
N1—H1	0.9000	C6—H6	1.0689
C2—N3	1.335 (4)	C7—C8	1.397 (4)
C2—C10	1.501 (4)	C7—H7	0.9663
N3—C9	1.384 (4)	C8—C9	1.393 (4)
N3—H3	0.9001	O1W—H2W	0.8500
C4—C5	1.379 (4)	O1W—H1W	0.8500
C4—C9	1.393 (4)
C2—N1—C8	108.6 (3)	C7—C6—H6	124
C2—N1—H1	130	C5—C6—H6	113
C8—N1—H1	121	C6—C7—C8	116.3 (3)
N3—C2—N1	108.9 (3)	C6—C7—H7	124
N3—C2—C10	125.9 (3)	C8—C7—H7	120
N1—C2—C10	125.1 (3)	N1—C8—C9	106.9 (3)
C2—N3—C9	109.5 (3)	N1—C8—C7	130.8 (3)
C2—N3—H3	126	C9—C8—C7	122.2 (3)
C9—N3—H3	124	N3—C9—C8	106.0 (3)
C5—C4—C9	116.5 (3)	N3—C9—C4	132.4 (3)
C5—C4—H4	123	C8—C9—C4	121.6 (3)
C9—C4—H4	120	O2—C10—O1	128.9 (3)
C4—C5—C6	121.5 (3)	O2—C10—C2	116.2 (3)
C4—C5—H5	120	O1—C10—C2	114.8 (3)
C6—C5—H5	117	H2W—O1W—H1W	107
C7—C6—C5	121.9 (3)
O1—C10—C2—N1	−4.2 (5)	O2—C10—C2—N1	174.1 (3)
O1—C10—C2—N3	178.7 (3)	O2—C10—C2—N3	−3.0 (5)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1W	0.90	1.76	2.646 (3)	166
N3—H3···O2^i	0.90	1.82	2.686 (3)	160
O1W—H2W···O1^ii	0.85	1.93	2.764 (3)	165
O1W—H1W···O1^iii	0.85	1.93	2.782 (3)	176

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