1H,1'H-2,2'-Bibenz­imidazole

In the title compound, C₁₄H₁₀N₄, all the atoms are close to being coplanar (r.m.s. deviation 0.0098 Å) except for the imino H atoms. The mol­ecule forms a one-dimensional chain through intermolecular N-H...N hydrogen bonds.

S1. Comment

The title compound, (I), is well known to act as a bridging ligand in transition metal compounds (Fieselmann et al., 1978; Haga et al., 1987). The asymmetric unit contains one quarter of the molecule and the other parts are twofold-rotation and mirror related. The rotation axis passes through the centre of the C1—C1' bond, while the mirror contains this bond. The occupancy of the imino H1 atom was set at 0.5 due to the mirror symmetry operation. The average bond distances and angles for the benzimidazole moiety are in good agreement with those of other substituted bis-benzimidazole compounds (Matthews et al., 1996; Ozbey et al., 1998; Bei et al., 2000). \scheme

The C1—C1' bond length of 1.435 (5) Å is close to the value for a single-bond length between trigonally linked C atoms (Cruickshank & Sparks, 1960; Bei et al., 2000). The molecule forms a one-dimensional chain through N1—H1···N1(x, −y, −1/2 − z) intermolecular hydrogen bonds.

S2. Experimental

The title compound was prepared from 1,2-diaminobenzene and oxamide according to the method of Fieselmann et al. (1978). Single crystals suitable for X-ray measurement were obtained by slow evaporation at room temperature from an ethylene glycol solution.

S3. Refinement

All the H atoms were located from the difference Fourier map and refined isotropically. The C—H range is 0.92 (3)–1.01 (2) Å and the N—H distance is 0.94 (4) Å.

Computing details

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1990); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN (Molecular Structure Corporation and Rigaku Corporation, 1999); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: TEXSAN; software used to prepare material for publication: TEXSAN.

(I)

Crystal data

C14H10N4	Dx = 1.354 Mg m^−3
Mr = 234.26	Mo Kα radiation, λ = 0.7107 Å
Orthorhombic, Ibam	Cell parameters from 25 reflections
Hall symbol: -I 2 2c	θ = 12.4–14.9°
a = 11.331 (3) Å	µ = 0.09 mm^−1
b = 10.183 (2) Å	T = 296 K
c = 9.962 (2) Å	Prismatic, yellow
V = 1149.4 (4) Å^3	0.30 × 0.10 × 0.10 mm
Z = 4

Data collection

Rigaku AFC-5R diffractometer	Rint = 0.015
ω–2θ scans	θmax = 27.5°
Absorption correction: ψ scan (North et al., 1968)	h = −1→14
Tmin = 0.937, Tmax = 0.996	k = −1→13
985 measured reflections	l = −1→12
703 independent reflections	3 standard reflections every 150 reflections
321 reflections with I > 2σ(I)	intensity decay: 0.6%

Refinement

Refinement on F^2	All H-atom parameters refined
R[F^2 > 2σ(F^2)] = 0.043	w = 1/[σ^2(Fo^2) + (0.045(Max(Fo^2,0) + 2Fc^2)/3)^2]
wR(F^2) = 0.127	(Δ/σ)max = 0.004
S = 1.06	Δρmax = 0.48 e Å^−3
703 reflections	Δρmin = −0.43 e Å^−3
55 parameters

Special details

Refinement. Refinement using reflections with F² > 0.0 σ(F²). The weighted R-factor (wR) and goodness of fit (S) are based on F². R-factor (gt) are based on F. The threshold expression of F² > 2.0 σ(F²) is used only for calculating R-factor (gt).

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
N1	0.8799 (1)	0.0477 (2)	−0.1130 (2)	0.0569 (6)
C1	0.9404 (2)	0.0241 (3)	0.0000	0.0504 (10)
C2	0.7704 (2)	0.0931 (2)	−0.0694 (2)	0.0513 (6)
C3	0.6723 (2)	0.1345 (3)	−0.1406 (3)	0.0743 (9)
C4	0.5757 (2)	0.1744 (3)	−0.0691 (3)	0.0669 (8)
H1	0.897 (3)	0.008 (4)	−0.196 (4)	0.046 (10)*	0.50
H2	0.674 (2)	0.137 (3)	−0.233 (3)	0.102 (9)*
H3	0.503 (2)	0.205 (2)	−0.119 (2)	0.076 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.045 (1)	0.082 (2)	0.045 (1)	0.009 (1)	−0.0070 (9)	0.000 (1)
C1	0.042 (2)	0.052 (2)	0.057 (2)	−0.006 (1)	0.0000	0.0000
C2	0.045 (1)	0.057 (1)	0.052 (1)	0.003 (1)	0.001 (1)	0.000 (1)
C3	0.060 (1)	0.105 (2)	0.058 (2)	0.022 (1)	−0.008 (1)	0.005 (2)
C4	0.050 (1)	0.077 (2)	0.074 (2)	0.017 (1)	−0.007 (1)	−0.001 (1)

Geometric parameters (Å, º)

N1—C1	1.339 (2)	C2—C3	1.385 (3)
N1—C2	1.394 (3)	C3—C4	1.367 (4)
N1—H1	0.94 (4)	C3—H2	0.92 (3)
C1—C1^i	1.436 (6)	C4—C4^ii	1.377 (5)
C2—C2^ii	1.382 (4)	C4—H3	1.01 (2)
N1···H3^iii	2.88 (2)	C2···H3^iii	3.38 (2)
N1···N1^iv	2.898 (4)	C2···H2^xii	3.44 (3)
N1···H1^v	3.19 (3)	C3···H2^iv	3.04 (3)
N1···H2^iv	3.37 (3)	C3···H2^xii	3.17 (3)
C1···H1^vi	2.70 (3)	C3···H3^xiii	3.20 (2)
C1···H3^vii	3.09 (2)	C3···H1^iv	3.36 (3)
C1···H3^iii	3.09 (2)	C3···C3^iv	3.501 (6)
C1···H1^iv	3.09 (4)	C4···H3^xiii	3.25 (2)
C1···H1^viii	3.09 (4)	C4···H2^xiii	3.47 (3)
C1···C4^vii	3.500 (4)	H1···H1^v	2.56 (6)
C1···C4^iii	3.500 (4)	H1···H2^iv	3.02 (4)
C1···H3^ix	3.52 (2)	H1···H3^iii	3.25 (5)
C1···H3^x	3.52 (2)	H1···H3^x	3.37 (5)
C1···H1^v	3.55 (4)	H2···H3^xiii	2.59 (4)
C1···H1^xi	3.55 (4)	H2···H2^iv	2.81 (5)
C1···C2^vi	3.555 (4)	H2···H2^xii	2.89 (5)
C2···H1^iv	2.93 (3)	H3···H3^xiii	2.61 (4)
C2···H2^iv	3.25 (3)
C1—N1—C2	104.7 (2)	C2^ii—C2—C3	120.8 (1)
C1—N1—H1	123 (2)	C2—C3—C4	117.8 (2)
C2—N1—H1	127 (1)	C2—C3—H2	120 (1)
N1—C1—N1^ii	114.3 (3)	C4—C3—H2	121 (1)
N1—C1—C1^i	122.8 (1)	C3—C4—C4^ii	121.4 (2)
N1—C1^ii—C1^i	122.8 (1)	C3—C4—H3	119 (1)
N1—C2—C2^ii	108.2 (1)	C4^ii—C4—H3	119 (1)
N1—C2—C3	131.0 (2)
N1—C1—N1^ii—C2^ii	−1.1 (3)	C1—N1—C2—C3	179.0 (3)
N1—C1—C1^i—N1^i	0.9 (7)	C1—N1^ii—C2^ii—C2	0.6 (2)
N1—C1—C1^i—N1^vi	180.0	C1—N1^ii—C2^ii—C3^ii	−179.0 (3)
N1—C2—C2^ii—N1^ii	0.0	C2—C2^ii—C3^ii—C4^ii	0.4 (3)
N1—C2—C2^ii—C3^ii	179.6 (3)	C2—C3—C4—C4^ii	0.4 (3)
N1—C2—C3—C4	−179.9 (2)	C3—C2—C2^ii—C3^ii	0.0
C1—N1—C2—C2^ii	−0.6 (2)	C3—C4—C4^ii—C3^ii	0.0

Symmetry codes: (i) −x+2, −y, z; (ii) x, y, −z; (iii) x+1/2, −y+1/2, z; (iv) x, −y, −z−1/2; (v) −x+2, y, −z−1/2; (vi) −x+2, −y, −z; (vii) x+1/2, −y+1/2, −z; (viii) x, −y, z+1/2; (ix) −x+3/2, y−1/2, −z; (x) −x+3/2, y−1/2, z; (xi) −x+2, y, z+1/2; (xii) −x+3/2, −y+1/2, −z−1/2; (xiii) −x+1, y, −z−1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···N1^iv	0.94 (4)	1.99 (4)	2.897 (3)	160 (3)

Symmetry code: (iv) x, −y, −z−1/2.