4-Chloro-2-[1-(5-chloro-2-hydroxy­benz­yl)-1H-benzimidazol-2-yl]phenol

The title compound, C₂₀H₁₄Cl₂N₂O₂, was prepared by the one-step condensation of o-phenyl­enediamine with 5-chloro-2-hydroxy­benzaldehyde. The dihedral angles between the benzimidaloe ring system and the benzene rings are 77.2 (2) and 87.1 (2)° Mol­ecules are linked by O—H...N inter­molecular hydrogen bonds, forming one-dimensional infinite chains, and the chains are linked by C—Cl...π(Ar) inter­actions, forming a two-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.067
• wR factor = 0.211
• Data-to-parameter ratio = 18.7

checkCIF/PLATON results

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Alert level B
PLAT420_ALERT_2_B D-H Without Acceptor       O1     -   H1     ...          ?

Alert level C
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          5
PLAT482_ALERT_4_C Small D-H..A Angle Rep for C20    ..  N2      ..      99.70 Deg.
PLAT602_ALERT_4_C VERY LARGE Solvent Accessible VOID(S) in Structure        !

   0 ALERT level A = In general: serious problem
   1 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
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Benzimidazole derivatives and their metal complexes display wide-ranging biological activities in chemical and biological profiles, for example as antitumoral, antiparasitic, antifungal, anti-HIV, anticancer, antiviral and antimicrobial agents (Boiani et al., 2005; Eltayeb et al. 2007). The benzimidazole derivatives can be prepared by one-step condensation of o-phenylenediamine with relative aromatic aldehyde (Yang et al., 2004). Some similar structures have been reported previously for the derivatives of 2-chlorobenzaldehyde (Jian et al., 2006), 4-chlorobenzaldehyde (Yang et al., 2007a), 4-(dimethylamino)benzaldehyde (Sheikhshoaie et al., 2006; Yang et al., 2007b), 5-bromo-2-hydroxy-3-methoxybenzaldehyde (Yang et al., 2006) and 8-methoxy-1-naphthaldehyde (Eltayeb et al., 2007). Considering the biological importance of benzimidazole derivatives, we present here the crystal structure of the title compound (I).

In the crystal structure of (I) (Fig. 1), the C—C and C—N bond lengths are within normal ranges and comparable to values found by Yang et al. (2006). The benzimidazole system is essentially planar and well conjugated, with a dihedral angle of 0.6 (2)° between the planes of the benzene ring and its fused imidazole ring. The conformation of the overall molecule can be described by dihedral angles between the benzimidazole-ring and C8—C13 ring systems of 77.7 (2)°, and between the benzimidazole-ring and C15—C20 ring systems of 87.1 (2)°. The 5-chloro-2-hydroxybenzyl and 5-chloro-2-hydroxyphenyl groups make an angle of 86.7 (2)° with each other.

There are two kinds of weak intramolecular hydrogen bonds, C—H···O and C—H···N, which generate two S(5) ring motif (Bernstein et al., 1995) in the molecule. The molecules of the title compound are linked by O2—H···N1ⁱ hydrogen bonds, forming an one-dimensional infinite chains along the [010] direction (Fig. 2) [symmetry code: (i) x, y + 1, z]. No π-π interaction is found in the structure, whereas the chains are linked by C12—Cl1···π(Ar, the centroidⁱⁱ of C1—C6 ring) interaction to form two-dimensional networks (Fig. 3) [the distance of Cl···Cg is 3.6.7 (2) Å and the angle of C—Cl···Cg is 137.4 (2)°] [symmetry code: (ii) x, 1.5 - y, 0.5 + z]. The packing is further stabilized by van der Waals forces.

Related literature

For related literature, see: Boiani & Gonzalez (2005); Eltayeb et al. (2007); Jian et al. (2006); Sheikhshoaie et al. (2006); Spek (2003, 2005); Yang et al. (2004, 2006, 2007a,b); Yang, Han et al. (2007); Yang, Wang et al. (2007); Bernstein et al. (1995).

S2. Experimental

A solution of 0.108 g (1 m mol) o-phenylenediamine, 0.313 g (2 m mol) 5-chloro-2-hydroxybenzaldehyde and 20 ml me thonal was heated for 1 h under reflux and ultrasonic radiation. The reaction mixture was then cooled and the pale yellow precipitate that had formed was filtered off with yield of 67%. Recrystallization of the crude product from ethanol solution resulted in single crystals of (I) suitable for X-ray diffraction analysis after several days.

S3. Refinement

Some residual electron density in the accesible voids of the structure was difficult to model. The deepest hole in the final Fourier map is 3.81 Å from atom H14A. Therefore the SQUEEZE function of PLATON (Spek, 2003) was used to eliminate the contribution of the electron density in the solvent region from the intensity data, and the solvent-free model was employed for the final refinement. The volume which is accessible for potential solvent molecules was calculated to be 643.0 A³ and the total electron count per cell was calculated to be 106. Note that the calculated density, the F(000) value, the molecular weight and the formula are given without taking into account the results obtained with the SQUEEZE option in PLATON (Spek, 2003). All the H atoms were positioned in idealized locations and refined as riding on their carrier atoms, with O—H distances of 0.82 (hydroxyl), C—H distances of 0.93 (aryl) and 0.97 Å (methylene) with U_iso(H) = 1.5U_eq(O) for hydroxyl, U_iso(H) = 1.2U_eq(C) for the other atoms.

Computing details

Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2; data reduction: APEX2; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: APEX2; software used to prepare material for publication: APEX2 and publCIF (Westrip, 2007).

Figures

	Fig. 1. Molecular structure of (I), showing 25% probability displacement ellipsoids.
	Fig. 2. The packing diagram of (I), viewed down the a axis, All the non-hydroxyl H atoms have been omitted for clarity.
	Fig. 3. The C—Cl···π(Ar) interaction in the packing of (I), viewed down the b axis., All the non-hydroxyl H atoms have been omitted for clarity.

4-Chloro-2-[1-(5-chloro-2-hydroxybenzyl)-1H-benzimidazol-2-yl]phenol

Crystal data

C20H14Cl2N2O2	F(000) = 792
Mr = 385.23	Dx = 1.132 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1705 reflections
a = 13.4393 (11) Å	θ = 2.2–18.8°
b = 8.9757 (7) Å	µ = 0.30 mm^−1
c = 18.8114 (15) Å	T = 296 K
β = 95.033 (1)°	Block, pale yellow
V = 2260.4 (3) Å^3	0.25 × 0.20 × 0.13 mm
Z = 4

Data collection

Bruker APEX-II area-detector diffractometer	4432 independent reflections
Radiation source: fine-focus sealed tube	2296 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.052
ϕ and ω scan	θmax = 26.0°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −16→16
Tmin = 0.92, Tmax = 0.96	k = −11→11
15245 measured reflections	l = −23→22

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)] = 0.067	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.211	H-atom parameters constrained
S = 1.00	w = 1/[σ^2(Fo^2) + (0.1107P)^2] where P = (Fo^2 + 2Fc^2)/3
4432 reflections	(Δ/σ)max < 0.001
237 parameters	Δρmax = 0.44 e Å^−3
0 restraints	Δρmin = −0.29 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
C1	0.5263 (2)	0.6889 (4)	0.13250 (17)	0.0565 (8)
C2	0.5229 (2)	0.8419 (3)	0.13514 (17)	0.0555 (8)
C3	0.4650 (3)	0.9273 (5)	0.0858 (2)	0.0778 (11)
H3	0.4635	1.0308	0.0876	0.093*
C4	0.4096 (3)	0.8459 (7)	0.0334 (3)	0.1001 (15)
H4	0.3701	0.8976	−0.0014	0.120*
C5	0.4101 (3)	0.6935 (6)	0.0304 (2)	0.0961 (14)
H5	0.3702	0.6452	−0.0053	0.115*
C6	0.4682 (3)	0.6112 (5)	0.0790 (2)	0.0787 (11)
H6	0.4692	0.5077	0.0768	0.094*
C7	0.6265 (2)	0.7535 (3)	0.22244 (17)	0.0496 (8)
C8	0.6978 (2)	0.7501 (3)	0.28621 (19)	0.0553 (8)
C9	0.7996 (3)	0.7232 (4)	0.2781 (2)	0.0681 (9)
C10	0.8665 (3)	0.7139 (5)	0.3379 (3)	0.0919 (13)
H10	0.9334	0.6940	0.3328	0.110*
C11	0.8351 (4)	0.7338 (5)	0.4053 (2)	0.0891 (13)
H11	0.8810	0.7299	0.4452	0.107*
C12	0.7351 (3)	0.7595 (4)	0.4129 (2)	0.0746 (11)
C13	0.6678 (3)	0.7696 (3)	0.35376 (19)	0.0640 (9)
H13	0.6011	0.7898	0.3594	0.077*
C14	0.6075 (2)	1.0372 (3)	0.21725 (18)	0.0586 (8)
H14A	0.6327	1.0355	0.2672	0.070*
H14B	0.5449	1.0917	0.2136	0.070*
C15	0.6809 (2)	1.1189 (3)	0.17565 (15)	0.0507 (8)
C16	0.6782 (2)	1.2735 (3)	0.17478 (18)	0.0558 (8)
C17	0.7485 (3)	1.3551 (4)	0.14095 (19)	0.0702 (10)
H17	0.7477	1.4587	0.1419	0.084*
C18	0.8192 (3)	1.2801 (4)	0.1061 (2)	0.0731 (10)
H18	0.8658	1.3337	0.0827	0.088*
C19	0.8219 (2)	1.1288 (4)	0.10552 (18)	0.0643 (9)
C20	0.7541 (2)	1.0472 (4)	0.14033 (17)	0.0589 (8)
H20	0.7572	0.9437	0.1402	0.071*
Cl1	0.69503 (11)	0.78143 (16)	0.49766 (6)	0.1145 (5)
Cl2	0.91134 (8)	1.03568 (13)	0.06080 (7)	0.1035 (5)
N1	0.59146 (19)	0.6339 (3)	0.18823 (14)	0.0554 (7)
N2	0.58792 (18)	0.8822 (3)	0.19284 (13)	0.0505 (6)
O1	0.82533 (19)	0.7035 (3)	0.21081 (14)	0.0859 (8)
H1	0.8828	0.6724	0.2121	0.129*
O2	0.60531 (19)	1.3402 (2)	0.20982 (14)	0.0739 (7)
H2	0.6091	1.4309	0.2055	0.111*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.059 (2)	0.0566 (19)	0.056 (2)	−0.0079 (15)	0.0133 (17)	0.0022 (16)
C2	0.059 (2)	0.0490 (19)	0.059 (2)	−0.0008 (15)	0.0104 (17)	0.0079 (15)
C3	0.082 (3)	0.082 (3)	0.068 (2)	0.003 (2)	0.001 (2)	0.017 (2)
C4	0.078 (3)	0.136 (4)	0.083 (3)	−0.004 (3)	−0.011 (2)	0.032 (3)
C5	0.090 (3)	0.127 (4)	0.068 (3)	−0.031 (3)	−0.013 (2)	0.005 (3)
C6	0.087 (3)	0.081 (3)	0.068 (3)	−0.023 (2)	0.012 (2)	−0.016 (2)
C7	0.0498 (17)	0.0387 (16)	0.062 (2)	0.0024 (13)	0.0130 (15)	0.0054 (14)
C8	0.059 (2)	0.0398 (16)	0.067 (2)	0.0034 (14)	0.0061 (17)	0.0029 (14)
C9	0.064 (2)	0.072 (2)	0.070 (2)	0.0080 (18)	0.0109 (19)	0.0053 (18)
C10	0.063 (3)	0.122 (4)	0.089 (3)	0.017 (2)	−0.003 (2)	0.009 (3)
C11	0.088 (3)	0.106 (3)	0.070 (3)	0.013 (2)	−0.015 (2)	0.008 (2)
C12	0.085 (3)	0.074 (2)	0.064 (2)	0.014 (2)	0.003 (2)	0.0025 (18)
C13	0.070 (2)	0.057 (2)	0.065 (2)	0.0086 (16)	0.0091 (19)	0.0035 (16)
C14	0.066 (2)	0.0409 (18)	0.071 (2)	0.0042 (14)	0.0166 (17)	−0.0015 (14)
C15	0.0566 (19)	0.0449 (18)	0.0500 (18)	−0.0037 (14)	0.0006 (15)	−0.0015 (13)
C16	0.055 (2)	0.052 (2)	0.061 (2)	0.0017 (15)	0.0071 (16)	−0.0013 (15)
C17	0.081 (3)	0.055 (2)	0.077 (2)	−0.0106 (18)	0.016 (2)	−0.0008 (17)
C18	0.065 (2)	0.079 (3)	0.078 (3)	−0.0224 (19)	0.018 (2)	−0.0074 (19)
C19	0.051 (2)	0.070 (2)	0.073 (2)	−0.0088 (17)	0.0127 (17)	−0.0137 (17)
C20	0.058 (2)	0.0500 (19)	0.069 (2)	−0.0010 (15)	0.0065 (17)	−0.0065 (15)
Cl1	0.1381 (11)	0.1426 (11)	0.0631 (7)	0.0356 (8)	0.0100 (7)	0.0012 (6)
Cl2	0.0804 (7)	0.1029 (9)	0.1341 (10)	−0.0098 (6)	0.0470 (7)	−0.0360 (7)
N1	0.0611 (16)	0.0391 (14)	0.0673 (17)	−0.0018 (12)	0.0122 (14)	−0.0035 (12)
N2	0.0555 (15)	0.0396 (14)	0.0567 (16)	−0.0010 (11)	0.0069 (13)	0.0048 (11)
O1	0.0631 (16)	0.116 (2)	0.0796 (19)	0.0126 (15)	0.0140 (14)	0.0064 (15)
O2	0.0855 (17)	0.0362 (12)	0.1045 (19)	0.0031 (11)	0.0339 (15)	−0.0008 (12)

Geometric parameters (Å, º)

C1—C2	1.375 (5)	C11—H11	0.9300
C1—N1	1.396 (4)	C12—C13	1.374 (5)
C1—C6	1.404 (5)	C12—Cl1	1.737 (4)
C2—N2	1.381 (4)	C13—H13	0.9300
C2—C3	1.389 (5)	C14—N2	1.482 (4)
C3—C4	1.388 (6)	C14—C15	1.503 (4)
C3—H3	0.9300	C14—H14A	0.9700
C4—C5	1.369 (7)	C14—H14B	0.9700
C4—H4	0.9300	C15—C16	1.388 (4)
C5—C6	1.366 (6)	C15—C20	1.392 (4)
C5—H5	0.9300	C16—O2	1.367 (4)
C6—H6	0.9300	C16—C17	1.392 (4)
C7—N1	1.317 (4)	C17—C18	1.376 (5)
C7—N2	1.365 (4)	C17—H17	0.9300
C7—C8	1.468 (5)	C18—C19	1.359 (5)
C8—C13	1.378 (5)	C18—H18	0.9300
C8—C9	1.411 (5)	C19—C20	1.379 (4)
C9—O1	1.353 (4)	C19—Cl2	1.740 (3)
C9—C10	1.379 (5)	C20—H20	0.9300
C10—C11	1.382 (6)	O1—H1	0.8200
C10—H10	0.9300	O2—H2	0.8200
C11—C12	1.384 (6)
C2—C1—N1	110.3 (3)	C13—C12—Cl1	120.0 (3)
C2—C1—C6	120.3 (3)	C11—C12—Cl1	119.8 (3)
N1—C1—C6	129.4 (3)	C12—C13—C8	120.9 (4)
C1—C2—N2	105.6 (3)	C12—C13—H13	119.5
C1—C2—C3	123.1 (3)	C8—C13—H13	119.5
N2—C2—C3	131.3 (3)	N2—C14—C15	113.8 (2)
C4—C3—C2	114.7 (4)	N2—C14—H14A	108.8
C4—C3—H3	122.6	C15—C14—H14A	108.8
C2—C3—H3	122.6	N2—C14—H14B	108.8
C5—C4—C3	123.4 (4)	C15—C14—H14B	108.8
C5—C4—H4	118.3	H14A—C14—H14B	107.7
C3—C4—H4	118.3	C16—C15—C20	118.4 (3)
C6—C5—C4	121.2 (4)	C16—C15—C14	118.4 (3)
C6—C5—H5	119.4	C20—C15—C14	123.1 (3)
C4—C5—H5	119.4	O2—C16—C15	116.8 (3)
C5—C6—C1	117.4 (4)	O2—C16—C17	122.3 (3)
C5—C6—H6	121.3	C15—C16—C17	120.9 (3)
C1—C6—H6	121.3	C18—C17—C16	119.0 (3)
N1—C7—N2	112.6 (3)	C18—C17—H17	120.5
N1—C7—C8	124.2 (3)	C16—C17—H17	120.5
N2—C7—C8	123.2 (3)	C19—C18—C17	120.9 (3)
C13—C8—C9	119.1 (3)	C19—C18—H18	119.6
C13—C8—C7	121.9 (3)	C17—C18—H18	119.6
C9—C8—C7	119.0 (3)	C18—C19—C20	120.5 (3)
O1—C9—C10	123.6 (4)	C18—C19—Cl2	120.3 (3)
O1—C9—C8	116.9 (3)	C20—C19—Cl2	119.2 (3)
C10—C9—C8	119.4 (4)	C19—C20—C15	120.3 (3)
C9—C10—C11	120.7 (4)	C19—C20—H20	119.8
C9—C10—H10	119.6	C15—C20—H20	119.8
C11—C10—H10	119.6	C7—N1—C1	104.6 (2)
C10—C11—C12	119.6 (4)	C7—N2—C2	106.9 (2)
C10—C11—H11	120.2	C7—N2—C14	128.1 (3)
C12—C11—H11	120.2	C2—N2—C14	124.9 (3)
C13—C12—C11	120.2 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···N1^i	0.82	1.86	2.671 (3)	169
C20—H20···N2	0.93	2.62	2.923 (4)	100
C14—H14B···O2	0.97	2.38	2.723 (3)	100

Symmetry code: (i) x, y+1, z.