Dimethyl 2,2′-[2,2′-bi(1H-1,3-benzimidazole)-1,1′-di­yl]diacetate

Abstract

The whole mol­ecule of the title compound, C₂₀H₁₈N₄O₄, is generated by an inversion center. The benzimidazole ring mean plane make a dihedral angle of 89.4 (8)° with the plane passing through the acetate group (COO). In the crystal, mol­ecules are linked via weak C—H⋯O hydrogen bonds and π–π inter­actions [centroid–centroid distance = 3.743 (3) Å] involving inversion-related benzimidazole groups.

Related literature  

For related structures, see: Al-Mohammed et al. (2012 ▶); Fu & Xu (2009 ▶); Xu & Wang (2008 ▶). For the synthesis of 2,2′-bibenzimidazole, see: Tang et al. (2007 ▶).

Experimental  

Crystal data  

• C₂₀H₁₈N₄O₄

• M _r = 378.38

• Triclinic,

• a = 6.904 (4) Å

• b = 8.494 (5) Å

• c = 8.643 (5) Å

• α = 67.191 (5)°

• β = 70.360 (5)°

• γ = 87.172 (5)°

• V = 438.1 (4) ų

• Z = 1

• Mo Kα radiation

• μ = 0.10 mm⁻¹

• T = 296 K

• 0.33 × 0.31 × 0.29 mm

Data collection  

• Bruker APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.967, T _max = 0.971

• 3034 measured reflections

• 1600 independent reflections

• 1172 reflections with I > 2σ(I)

• R _int = 0.027

Refinement  

• R[F ² > 2σ(F ²)] = 0.048

• wR(F ²) = 0.127

• S = 1.06

• 1600 reflections

• 128 parameters

• H-atom parameters constrained

• Δρ_max = 0.14 e Å⁻³

• Δρ_min = −0.25 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); 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

Supplementary material file. DOI: 10.1107/S1600536812032266/su2479Isup3.cml

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
C8—H8B⋯O1i	0.97	2.59	3.364 (3)	137
C10—H10C⋯O1ii	0.96	2.55	3.481 (4)	164

Symmetry codes: (i) ; (ii) .

supplementary crystallographic information

Comment

The whole molecule of the title compound (Fig.1) is generated by an inversion center. The benzimidazole system is essentially planar, with a dihedral angle of 0.8 (5)° between the planes of the benzene and imidazole rings. The benzimidazole ring make a dihedral angle of 89.4 (8)° with the plane passing through the acetate group (C9/O1/O2). This value is comparable to that observed in some similar structures (Al-Mohammed et al., 2012; Fu et al., 2009; Xu et al., 2008).

In the crystal, weak intermolecular C—H···O hydrogen bonds (Table 1 and Fig. 2) and π–π stacking interactions [Cg1···Cg2ⁱ = 3.743 (3) Å, where Cg1 is the centroid of ring N1/C1/C6/N2/C7; Cg2 is the centroid of ring C1-C6; symmetry code: (i) -x+1, -y+1, -z+1] stabilize the crystal structure.

Experimental

The synthesis of 2,2'-bibenzimidazole [systematic name: 1H,1'H-2,2'-bibenzo[d]imidazole] has been reported (Tang et al., 2007). A mixture of 2,2'-bibenzimidazole (11.71 g, 50 mmol) and NaOH (4.00 g, 100 mmol) in DMSO (40 mL) was stirred at 278 K for 2 h, and then methyl chloroacetate (10.85 g, 100 mmol) was added. The mixture was cooled to room temperature after stirring at 353 K for 24 h, and then poured into 200 mL of water. A yellow solid formed immediately, which was isolated by filtration. The crude product was then crystallized from methanol. Single crystals of the title compound, suitable for X-ray analysis, were obtained by slow evaporation of a solution in methanol.

Refinement

The C-bound H-atoms were included in calculated positions and treated as riding atoms: C-H = 0.93, 0.96 and 0.97 Å for CH, CH₃ and CH₂ H-atoms, respectively, with U_iso(H) = k × U_eq(parent C-atom), where k = 1.5 for CH₃ H-atoms and = 1.2 for other H-atoms.

Figures

Fig. 1.

The molecular structure of the title molecule with the atom numbering [symmetry code for suffix A: -x, -y+1, -z+1]. Displacement ellipsoids are drawn at the 30% probability level

Fig. 2.

The crystal packing of the title compound, viewed along the b axis. Weak C—H···O interaction are shown as dashed lines.

Crystal data

C20H18N4O4	Z = 1
Mr = 378.38	F(000) = 198
Triclinic, P1	Dx = 1.434 Mg m−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.904 (4) Å	Cell parameters from 853 reflections
b = 8.494 (5) Å	θ = 2.6–23.8°
c = 8.643 (5) Å	µ = 0.10 mm−1
α = 67.191 (5)°	T = 296 K
β = 70.360 (5)°	Block, brown
γ = 87.172 (5)°	0.33 × 0.31 × 0.29 mm
V = 438.1 (4) Å3

Data collection

Bruker APEXII CCD diffractometer	1600 independent reflections
Radiation source: fine-focus sealed tube	1172 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
φ and ω scans	θmax = 25.5°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −8→8
Tmin = 0.967, Tmax = 0.971	k = −9→10
3034 measured reflections	l = −10→10

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.048	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.127	H-atom parameters constrained
S = 1.06	w = 1/[σ2(Fo2) + (0.0656P)2 + 0.0023P] where P = (Fo2 + 2Fc2)/3
1600 reflections	(Δ/σ)max < 0.001
128 parameters	Δρmax = 0.14 e Å−3
0 restraints	Δρmin = −0.25 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	0.3492 (3)	0.6658 (2)	0.5117 (2)	0.0382 (5)
C2	0.5275 (3)	0.7663 (3)	0.4646 (3)	0.0485 (6)
H2	0.6033	0.8332	0.3460	0.058*
C3	0.5865 (4)	0.7619 (3)	0.6022 (3)	0.0539 (6)
H3	0.7063	0.8271	0.5762	0.065*
C4	0.4722 (4)	0.6624 (3)	0.7808 (3)	0.0533 (6)
H4	0.5173	0.6635	0.8704	0.064*
C5	0.2955 (3)	0.5636 (3)	0.8265 (3)	0.0497 (6)
H5	0.2197	0.4979	0.9454	0.060*
C6	0.2327 (3)	0.5645 (2)	0.6892 (2)	0.0397 (5)
C7	0.0742 (3)	0.5291 (2)	0.5281 (2)	0.0385 (5)
C8	0.3089 (3)	0.7314 (2)	0.2179 (2)	0.0433 (5)
H8A	0.2674	0.6583	0.1696	0.052*
H8B	0.4585	0.7504	0.1691	0.052*
C9	0.2220 (3)	0.9010 (3)	0.1547 (3)	0.0435 (5)
C10	0.0081 (4)	1.1015 (3)	0.2334 (4)	0.0720 (8)
H10A	0.1162	1.1933	0.1612	0.108*
H10B	−0.0752	1.1195	0.3382	0.108*
H10C	−0.0764	1.0989	0.1659	0.108*
N1	0.2463 (2)	0.64117 (18)	0.41008 (19)	0.0388 (4)
N2	0.0622 (3)	0.4797 (2)	0.6961 (2)	0.0435 (5)
O1	0.2651 (3)	0.9897 (2)	−0.00051 (19)	0.0731 (6)
O2	0.0980 (2)	0.94015 (17)	0.28611 (18)	0.0535 (5)

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
C1	0.0432 (12)	0.0319 (10)	0.0357 (10)	0.0078 (9)	−0.0109 (9)	−0.0122 (8)
C2	0.0521 (14)	0.0445 (12)	0.0380 (11)	−0.0018 (10)	−0.0083 (10)	−0.0104 (9)
C3	0.0519 (14)	0.0543 (13)	0.0493 (13)	−0.0041 (11)	−0.0148 (11)	−0.0153 (11)
C4	0.0571 (15)	0.0605 (14)	0.0434 (12)	0.0081 (12)	−0.0224 (11)	−0.0176 (11)
C5	0.0498 (14)	0.0542 (13)	0.0354 (11)	0.0099 (11)	−0.0134 (10)	−0.0094 (9)
C6	0.0429 (13)	0.0351 (10)	0.0329 (10)	0.0077 (9)	−0.0102 (9)	−0.0079 (8)
C7	0.0420 (12)	0.0299 (10)	0.0321 (10)	0.0035 (9)	−0.0063 (8)	−0.0059 (8)
C8	0.0497 (13)	0.0421 (11)	0.0280 (10)	−0.0052 (10)	−0.0030 (9)	−0.0110 (8)
C9	0.0431 (13)	0.0446 (12)	0.0335 (10)	−0.0084 (9)	−0.0131 (9)	−0.0044 (9)
C10	0.082 (2)	0.0443 (13)	0.0862 (18)	0.0167 (13)	−0.0383 (16)	−0.0158 (13)
N1	0.0442 (10)	0.0304 (8)	0.0302 (8)	0.0015 (7)	−0.0059 (7)	−0.0058 (7)
N2	0.0454 (11)	0.0396 (9)	0.0321 (9)	0.0036 (8)	−0.0079 (8)	−0.0049 (7)
O1	0.0739 (12)	0.0779 (12)	0.0375 (9)	0.0000 (10)	−0.0172 (8)	0.0073 (8)
O2	0.0684 (11)	0.0384 (8)	0.0470 (9)	0.0120 (7)	−0.0185 (8)	−0.0119 (7)

Geometric parameters (Å, º)

C1—N1	1.377 (3)	C7—N1	1.379 (2)
C1—C2	1.381 (3)	C7—C7i	1.449 (4)
C1—C6	1.398 (3)	C8—N1	1.448 (2)
C2—C3	1.368 (3)	C8—C9	1.503 (3)
C2—H2	0.9300	C8—H8A	0.9700
C3—C4	1.398 (3)	C8—H8B	0.9700
C3—H3	0.9300	C9—O1	1.194 (2)
C4—C5	1.367 (3)	C9—O2	1.321 (2)
C4—H4	0.9300	C10—O2	1.447 (3)
C5—C6	1.391 (3)	C10—H10A	0.9600
C5—H5	0.9300	C10—H10B	0.9600
C6—N2	1.383 (3)	C10—H10C	0.9600
C7—N2	1.320 (2)
N1—C1—C2	131.59 (18)	N1—C8—C9	115.16 (16)
N1—C1—C6	105.60 (18)	N1—C8—H8A	108.5
C2—C1—C6	122.81 (19)	C9—C8—H8A	108.5
C3—C2—C1	116.29 (19)	N1—C8—H8B	108.5
C3—C2—H2	121.9	C9—C8—H8B	108.5
C1—C2—H2	121.9	H8A—C8—H8B	107.5
C2—C3—C4	122.0 (2)	O1—C9—O2	124.6 (2)
C2—C3—H3	119.0	O1—C9—C8	121.8 (2)
C4—C3—H3	119.0	O2—C9—C8	113.58 (15)
C5—C4—C3	121.4 (2)	O2—C10—H10A	109.5
C5—C4—H4	119.3	O2—C10—H10B	109.5
C3—C4—H4	119.3	H10A—C10—H10B	109.5
C4—C5—C6	117.83 (19)	O2—C10—H10C	109.5
C4—C5—H5	121.1	H10A—C10—H10C	109.5
C6—C5—H5	121.1	H10B—C10—H10C	109.5
N2—C6—C5	130.18 (18)	C1—N1—C7	106.58 (15)
N2—C6—C1	110.13 (17)	C1—N1—C8	123.60 (16)
C5—C6—C1	119.7 (2)	C7—N1—C8	129.65 (17)
N2—C7—N1	112.52 (18)	C7—N2—C6	105.16 (16)
N2—C7—C7i	124.2 (2)	C9—O2—C10	116.11 (17)
N1—C7—C7i	123.3 (2)
N1—C1—C2—C3	179.33 (19)	C2—C1—N1—C8	−3.2 (3)
C6—C1—C2—C3	0.1 (3)	C6—C1—N1—C8	176.12 (16)
C1—C2—C3—C4	−0.5 (3)	N2—C7—N1—C1	−0.7 (2)
C2—C3—C4—C5	0.3 (3)	C7i—C7—N1—C1	−179.9 (2)
C3—C4—C5—C6	0.2 (3)	N2—C7—N1—C8	−176.09 (18)
C4—C5—C6—N2	−179.3 (2)	C7i—C7—N1—C8	4.8 (3)
C4—C5—C6—C1	−0.5 (3)	C9—C8—N1—C1	−87.6 (2)
N1—C1—C6—N2	0.0 (2)	C9—C8—N1—C7	87.1 (2)
C2—C1—C6—N2	179.38 (19)	N1—C7—N2—C6	0.7 (2)
N1—C1—C6—C5	−179.02 (17)	C7i—C7—N2—C6	179.9 (2)
C2—C1—C6—C5	0.4 (3)	C5—C6—N2—C7	178.5 (2)
N1—C8—C9—O1	178.39 (19)	C1—C6—N2—C7	−0.4 (2)
N1—C8—C9—O2	−1.1 (3)	O1—C9—O2—C10	1.1 (3)
C2—C1—N1—C7	−178.9 (2)	C8—C9—O2—C10	−179.49 (17)
C6—C1—N1—C7	0.42 (19)

Symmetry code: (i) −x, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8B···O1ii	0.97	2.59	3.364 (3)	137
C10—H10C···O1iii	0.96	2.55	3.481 (4)	164

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