1,4-Bis(2-benzimidazolyl)­benzene

The title compound, C₂₀H₁₄N₄, lies about an inversion centre and the benz­imidazole moiety and the phenyl ring are twisted by 30.9 (1)°. The benz­imidazole moiety is completely planar, with a maximum deviation of 0.009 (2) Å. Intermolecular N-­H...N hydrogen bonds give rise to a layered structure, with the layers stacked by van der Waals interactions.

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 1990).

(I)

Crystal data

C20H14N4	F(000) = 648
Mr = 310.35	Dx = 1.374 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 3853 reflections
a = 10.2400 (3) Å	θ = 2.7–28.3°
b = 9.7505 (2) Å	µ = 0.09 mm^−1
c = 15.0310 (4) Å	T = 293 K
V = 1500.77 (7) Å^3	Needle, dark red
Z = 4	0.50 × 0.12 × 0.10 mm

Data collection

Siemens SMART CCD area detector diffractometer	1223 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.076
Graphite monochromator	θmax = 28.3°, θmin = 2.7°
Detector resolution: 8.33 pixels mm^-1	h = −9→13
ω scans	k = −12→12
9577 measured reflections	l = −19→19
1846 independent reflections

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) = 0.155	H-atom parameters constrained
S = 1.12	w = 1/[σ^2(Fo^2) + (0.0584P)^2 + 0.4289P] where P = (Fo^2 + 2Fc^2)/3
1846 reflections	(Δ/σ)max < 0.001
109 parameters	Δρmax = 0.19 e Å^−3
0 restraints	Δρmin = −0.30 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. The data collection covered over a hemisphere of reciprocal space by a combination of three sets of exposures; each set had a different φ angle (0, 88 and 180°) for the crystal and each exposure of 10 s covered 0.3° in ω. The crystal-to-detector distance was 4 cm and the detector swing angle was -35°. Coverage of the unique set is over 99% complete. Crystal decay was monitored by repeating fifty initial frames at the end of data collection and analysing the duplicate reflections, and was found to be negligible.

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

	x	y	z	Uiso*/Ueq
N1	0.16043 (17)	0.05717 (17)	0.41094 (13)	0.0389 (5)
N2	0.20392 (17)	−0.16702 (16)	0.39828 (12)	0.0377 (5)
H2A	0.2467	−0.2428	0.4013	0.045*
C1	0.07906 (19)	−0.1500 (2)	0.36575 (14)	0.0353 (5)
C2	−0.0120 (2)	−0.2423 (2)	0.33129 (15)	0.0442 (6)
H2B	0.0062	−0.3355	0.3272	0.053*
C3	−0.1289 (2)	−0.1899 (2)	0.30385 (17)	0.0477 (6)
H3A	−0.1913	−0.2486	0.2799	0.057*
C4	−0.1571 (2)	−0.0490 (2)	0.31097 (17)	0.0491 (6)
H4A	−0.2374	−0.0163	0.2912	0.059*
C5	−0.0685 (2)	0.0409 (2)	0.34651 (17)	0.0458 (6)
H5A	−0.0884	0.1335	0.3523	0.055*
C6	0.0526 (2)	−0.0099 (2)	0.37380 (15)	0.0361 (5)
C7	0.2466 (2)	−0.04138 (19)	0.42458 (14)	0.0341 (5)
C8	0.37635 (19)	−0.02064 (19)	0.46375 (14)	0.0330 (5)
C9	0.4812 (2)	−0.1039 (2)	0.43866 (16)	0.0391 (5)
H9A	0.4680	−0.1767	0.3967	0.047*
C10	0.3967 (2)	0.0829 (2)	0.52542 (15)	0.0383 (5)
H10A	0.3251	0.1396	0.5440	0.046*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0270 (9)	0.0259 (9)	0.0638 (12)	0.0013 (7)	−0.0035 (8)	−0.0009 (8)
N2	0.0304 (9)	0.0240 (8)	0.0587 (11)	0.0004 (7)	−0.0025 (8)	−0.0006 (8)
C1	0.0299 (11)	0.0272 (10)	0.0488 (12)	−0.0021 (8)	0.0002 (9)	0.0025 (9)
C2	0.0437 (13)	0.0302 (11)	0.0588 (15)	−0.0065 (10)	−0.0068 (11)	−0.0008 (10)
C3	0.0393 (13)	0.0445 (13)	0.0594 (15)	−0.0134 (10)	−0.0090 (11)	0.0019 (12)
C4	0.0321 (12)	0.0512 (14)	0.0640 (15)	−0.0023 (10)	−0.0091 (11)	0.0079 (12)
C5	0.0354 (13)	0.0332 (11)	0.0688 (16)	0.0013 (9)	−0.0041 (11)	0.0026 (11)
C6	0.0277 (10)	0.0288 (10)	0.0516 (13)	−0.0017 (8)	0.0009 (9)	0.0014 (9)
C7	0.0286 (11)	0.0241 (9)	0.0496 (12)	−0.0009 (8)	0.0005 (9)	0.0002 (9)
C8	0.0261 (10)	0.0254 (9)	0.0475 (12)	0.0002 (8)	0.0006 (9)	0.0009 (9)
C9	0.0340 (12)	0.0290 (10)	0.0545 (13)	0.0046 (9)	−0.0018 (10)	−0.0088 (10)
C10	0.0291 (11)	0.0329 (11)	0.0529 (13)	0.0051 (9)	0.0034 (10)	−0.0043 (9)

Geometric parameters (Å, º)

N1—C7	1.320 (3)	C4—C5	1.370 (3)
N1—C6	1.400 (3)	C4—H4A	0.9300
N2—C7	1.359 (2)	C5—C6	1.396 (3)
N2—C1	1.379 (3)	C5—H5A	0.9300
N2—H2A	0.8600	C7—C8	1.468 (3)
C1—C2	1.395 (3)	C8—C10	1.386 (3)
C1—C6	1.398 (3)	C8—C9	1.398 (3)
C2—C3	1.365 (3)	C9—C10^i	1.377 (3)
C2—H2B	0.9300	C9—H9A	0.9600
C3—C4	1.409 (3)	C10—C9^i	1.377 (3)
C3—H3A	0.9300	C10—H10A	0.9600
C7—N1—C6	104.4 (2)	C4—C5—H5A	120.8
C7—N2—C1	107.0 (2)	C6—C5—H5A	120.8
C7—N2—H2A	126.5	C5—C6—C1	119.57 (19)
C1—N2—H2A	126.5	C5—C6—N1	130.68 (19)
N2—C1—C2	132.37 (19)	C1—C6—N1	109.75 (17)
N2—C1—C6	105.46 (17)	N1—C7—N2	113.34 (18)
C2—C1—C6	122.16 (19)	N1—C7—C8	124.54 (17)
C3—C2—C1	117.2 (2)	N2—C7—C8	122.13 (17)
C3—C2—H2B	121.4	C10—C8—C9	119.20 (19)
C1—C2—H2B	121.4	C10—C8—C7	120.32 (18)
C2—C3—C4	121.5 (2)	C9—C8—C7	120.48 (19)
C2—C3—H3A	119.3	C10^i—C9—C8	120.4 (2)
C4—C3—H3A	119.3	C10^i—C9—H9A	119.7
C5—C4—C3	121.2 (2)	C8—C9—H9A	120.0
C5—C4—H4A	119.4	C9^i—C10—C8	120.45 (19)
C3—C4—H4A	119.4	C9^i—C10—H10A	119.6
C4—C5—C6	118.4 (2)	C8—C10—H10A	119.9
C7—N2—C1—C2	−179.0 (2)	C7—N1—C6—C1	−0.4 (2)
C7—N2—C1—C6	0.5 (2)	C6—N1—C7—N2	0.7 (2)
N2—C1—C2—C3	−179.5 (2)	C6—N1—C7—C8	−179.5 (2)
C6—C1—C2—C3	1.1 (3)	C1—N2—C7—N1	−0.8 (3)
C1—C2—C3—C4	−0.7 (4)	C1—N2—C7—C8	179.42 (19)
C2—C3—C4—C5	−0.6 (4)	N1—C7—C8—C10	30.6 (3)
C3—C4—C5—C6	1.5 (4)	N2—C7—C8—C10	−149.6 (2)
C4—C5—C6—C1	−1.1 (3)	N1—C7—C8—C9	−148.6 (2)
C4—C5—C6—N1	179.3 (2)	N2—C7—C8—C9	31.1 (3)
N2—C1—C6—C5	−179.7 (2)	C10—C8—C9—C10^i	−0.2 (4)
C2—C1—C6—C5	−0.2 (3)	C7—C8—C9—C10^i	179.1 (2)
N2—C1—C6—N1	−0.1 (2)	C9—C8—C10—C9^i	0.2 (4)
C2—C1—C6—N1	179.5 (2)	C7—C8—C10—C9^i	−179.1 (2)
C7—N1—C6—C5	179.2 (2)

Symmetry code: (i) −x+1, −y, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···N1^ii	0.86	2.17	3.033 (2)	175

Symmetry code: (ii) −x+1/2, y−1/2, z.