2,2′-Dimeth­oxy-6,6′-dinitro­biphen­yl

Abstract

In the title compound, C₁₄H₁₂N₂O₆, the half mol­ecule in the asymmetric unit of the cell is completed by a crystallographic twofold rotation axis, and the two benzene rings of the complete mol­ecule make a dihedral angle of 60.5 (3)°. Furthermore, inter­molecular weak C—H⋯O hydrogen bonds link adjacent mol­ecules, forming a two-dimensional sheet. These sheets are stablized by face-to-face weak π–π contacts [centroid–centroid distance = 3.682 (1) Å] between the nearly parallel [dihedral angle = 0.12 (7)°] benzene rings of the neighboring mol­ecules, resulting in a three-dimensional network.

Related literature

For the synthesis of the title compound, see: Chen et al. (2001 ▶). For asymmetric synthesis using chiral ligands with C ₂ symmetry, see: Jiang et al. (2001 ▶); García et al. (2002 ▶). For synthetic methods for chiral compounds, see: Brunel (2005 ▶); Kočovský et al. (2003 ▶). For related biphenyl structures, see: Fischer et al. (2007 ▶). For related structural data see: Yang et al. (2005 ▶).

Experimental

Crystal data

• C₁₄H₁₂N₂O₆

• M _r = 304.26

• Monoclinic,

• a = 18.236 (3) Å

• b = 7.7826 (12) Å

• c = 10.9079 (17) Å

• β = 115.089 (2)°

• V = 1402.0 (4) ų

• Z = 4

• Mo Kα radiation

• μ = 0.12 mm⁻¹

• T = 294 K

• 0.30 × 0.18 × 0.18 mm

Data collection

• Bruker APEXII CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.966, T _max = 0.979

• 5102 measured reflections

• 1298 independent reflections

• 1009 reflections with I > 2σ(I)

• R _int = 0.019

Refinement

• R[F ² > 2σ(F ²)] = 0.035

• wR(F ²) = 0.097

• S = 1.03

• 1298 reflections

• 101 parameters

• H-atom parameters constrained

• Δρ_max = 0.14 e Å⁻³

• Δρ_min = −0.13 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); 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 ▶) and PLATON (Spek, 2009 ▶); software used to prepare material for publication: SHELXL97 and PLATON.

Supplementary Material

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
C7—H7B⋯O3i	0.96	2.48	3.426 (3)	169

Symmetry code: (i) .

supplementary crystallographic information

Comment

A large number of chiral compounds with C₂-symmetry are widely used as chiral auxiliaries and ligands in asymmetric synthesis and have shown high stereocontrol properties in a wide range of asymmetric transformations (Jiang et al. 2001; García et al. 2002). Design and synthesis of such compounds play a very important role in the development of highly enantioselective asymmetric reactions. Thus, it is not surprising that a lot of methods have been developed to obtain these chiral compounds (Brunel 2005; Kočovský et al. 2003). In this paper, we report the synthesis and crystal structure of the title compound with C₂-symmetry.

A view of the molecular structure of the title compound is given in Fig.1. All bond lengths and angles are in the expected range and in good agreement with those reported previously (Yang et al. 2005). The dihedral angle between two benzene rings is 60.5 (3)°, which is considerable larger than those found in other biphenyls (Fischer et al. 2007), possibly due to the concomitant effects of the steric hindrance of adjacent methoxy and nitro groups.

In the crystal structure, each molecule is connected by four adjacent molecules through intermolecular C—H···O hydrogen bonds (Table 1), between methoxy groups and O atoms of the adjacent nitro groups, leading to the formation of a two-dimensional sheet in the ac plane. The sheets are further connected into a three-dimensional network(Fig.2) by the face-to-face weak π–π contacts between nearly parallel benzene rings of the neighboring title molecules. The Cg1···Cg1ⁱⁱⁱ distance is 3.6823 (11) Å, the perpendicular distance between the rings is 3.410 Å, and the slippage between the rings is 1.389 Å. Cg1 is the centroid of the benzene ring C1 - C6, the symmetry code iii = 1 - x, -y, 1 - z.

Experimental

The title compound was synthesized by a reported method (Chen, et al. 2001),namely, a mixture of 2-iodo-3-nitroanisol (14 g, 0.05 mol) and activated copper brone (9.5 g, 0.15 mol), 50 ml of dimethylformamide was stirried at 140°C for 4 h under nitrogen atmosphere. Yellow crystals suitable for X-ray diffraction study were obtained from a solution in acetic ester.

Refinement

All of the non-hydrogen atoms were refined anisotropically. The hydrogen atoms were assigned with common isotropic displacement factors U_iso(H) = 1.2 times U_eq(C,N) and 1.5 times U_eq(O), respectively, and included in the final refinement by using geometrical restraints, with C–H distances of 0.93 Å.

Figures

Fig. 1.

ORTEP drawing (30% probability displacement ellipsoids) of a single molecule of the title compound.

Fig. 2.

three-dimensional structures of the title compound.

Crystal data

C14H12N2O6	F(000) = 632
Mr = 304.26	Dx = 1.441 Mg m−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1790 reflections
a = 18.236 (3) Å	θ = 2.5–25.7°
b = 7.7826 (12) Å	µ = 0.12 mm−1
c = 10.9079 (17) Å	T = 294 K
β = 115.089 (2)°	Block, yellow
V = 1402.0 (4) Å3	0.30 × 0.18 × 0.18 mm
Z = 4

Data collection

Bruker APEXII CCD area-detector diffractometer	1298 independent reflections
Radiation source: fine-focus sealed tube	1009 reflections with I > 2σ(I)
graphite	Rint = 0.019
φ and ω scans	θmax = 25.5°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −22→22
Tmin = 0.966, Tmax = 0.979	k = −9→9
5102 measured reflections	l = −13→13

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)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.097	H-atom parameters constrained
S = 1.03	w = 1/[σ2(Fo2) + (0.0401P)2 + 0.8036P] where P = (Fo2 + 2Fc2)/3
1298 reflections	(Δ/σ)max < 0.001
101 parameters	Δρmax = 0.14 e Å−3
0 restraints	Δρmin = −0.13 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 takeninto account individually in the estimation of e.s.d.'s in distances, anglesand torsion angles; correlations between e.s.d.'s in cell parameters are onlyused 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	0.49134 (9)	0.22562 (19)	0.67636 (14)	0.0387 (4)
C2	0.54245 (9)	0.2962 (2)	0.62577 (15)	0.0434 (4)
C3	0.52777 (12)	0.2896 (2)	0.49065 (17)	0.0546 (5)
H3	0.5639	0.3378	0.4607	0.066*
C4	0.45847 (12)	0.2102 (2)	0.40223 (17)	0.0588 (5)
H4	0.4471	0.2058	0.3107	0.071*
C5	0.40569 (11)	0.1370 (2)	0.44656 (16)	0.0540 (5)
H5	0.3589	0.0835	0.3852	0.065*
C6	0.42203 (9)	0.1426 (2)	0.58296 (15)	0.0444 (4)
C7	0.30000 (13)	−0.0071 (4)	0.5464 (2)	0.0944 (8)
H7A	0.2673	0.0767	0.4817	0.142*
H7B	0.2716	−0.0485	0.5971	0.142*
H7C	0.3110	−0.1012	0.4998	0.142*
N1	0.61559 (9)	0.3880 (2)	0.71661 (15)	0.0557 (4)
O1	0.37432 (7)	0.06986 (18)	0.63620 (11)	0.0594 (4)
O2	0.61327 (8)	0.47507 (17)	0.80791 (13)	0.0615 (4)
O3	0.67594 (9)	0.3739 (3)	0.69543 (17)	0.0967 (6)

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
C1	0.0399 (8)	0.0425 (8)	0.0345 (8)	0.0057 (6)	0.0166 (7)	0.0011 (6)
C2	0.0464 (9)	0.0454 (9)	0.0426 (8)	0.0044 (7)	0.0229 (7)	0.0023 (7)
C3	0.0722 (12)	0.0549 (10)	0.0508 (10)	0.0071 (9)	0.0399 (9)	0.0053 (8)
C4	0.0853 (14)	0.0566 (11)	0.0369 (8)	0.0117 (10)	0.0283 (10)	0.0036 (8)
C5	0.0610 (11)	0.0545 (10)	0.0372 (8)	0.0046 (9)	0.0119 (8)	−0.0031 (8)
C6	0.0452 (9)	0.0473 (9)	0.0388 (8)	0.0033 (7)	0.0159 (7)	0.0004 (7)
C7	0.0600 (13)	0.142 (2)	0.0750 (14)	−0.0445 (14)	0.0224 (12)	−0.0253 (15)
N1	0.0500 (8)	0.0679 (10)	0.0571 (9)	−0.0031 (7)	0.0302 (7)	0.0073 (8)
O1	0.0473 (7)	0.0794 (9)	0.0474 (7)	−0.0193 (6)	0.0162 (6)	−0.0058 (6)
O2	0.0612 (8)	0.0665 (8)	0.0570 (7)	−0.0133 (6)	0.0253 (6)	−0.0081 (7)
O3	0.0604 (9)	0.1503 (16)	0.0999 (12)	−0.0197 (10)	0.0538 (9)	−0.0120 (11)

Geometric parameters (Å, °)

C1—C2	1.383 (2)	C5—C6	1.389 (2)
C1—C6	1.400 (2)	C5—H5	0.9300
C1—C1i	1.500 (3)	C6—O1	1.3576 (19)
C2—C3	1.383 (2)	C7—O1	1.424 (2)
C2—N1	1.466 (2)	C7—H7A	0.9600
C3—C4	1.370 (3)	C7—H7B	0.9600
C3—H3	0.9300	C7—H7C	0.9600
C4—C5	1.371 (3)	N1—O2	1.2200 (18)
C4—H4	0.9300	N1—O3	1.2217 (18)
C2—C1—C6	116.51 (13)	C6—C5—H5	120.0
C2—C1—C1i	123.77 (15)	O1—C6—C5	124.06 (15)
C6—C1—C1i	119.63 (14)	O1—C6—C1	115.19 (13)
C1—C2—C3	123.51 (15)	C5—C6—C1	120.75 (15)
C1—C2—N1	119.86 (13)	O1—C7—H7A	109.5
C3—C2—N1	116.60 (14)	O1—C7—H7B	109.5
C4—C3—C2	118.11 (16)	H7A—C7—H7B	109.5
C4—C3—H3	120.9	O1—C7—H7C	109.5
C2—C3—H3	120.9	H7A—C7—H7C	109.5
C3—C4—C5	121.01 (15)	H7B—C7—H7C	109.5
C3—C4—H4	119.5	O2—N1—O3	123.39 (16)
C5—C4—H4	119.5	O2—N1—C2	119.06 (13)
C4—C5—C6	120.08 (17)	O3—N1—C2	117.55 (16)
C4—C5—H5	120.0	C6—O1—C7	118.46 (14)
C6—C1—C2—C3	0.7 (2)	C2—C1—C6—O1	178.01 (14)
C1i—C1—C2—C3	177.26 (13)	C1i—C1—C6—O1	1.26 (19)
C6—C1—C2—N1	178.92 (14)	C2—C1—C6—C5	−1.6 (2)
C1i—C1—C2—N1	−4.5 (2)	C1i—C1—C6—C5	−178.36 (13)
C1—C2—C3—C4	0.6 (3)	C1—C2—N1—O2	−36.5 (2)
N1—C2—C3—C4	−177.73 (16)	C3—C2—N1—O2	141.90 (16)
C2—C3—C4—C5	−0.9 (3)	C1—C2—N1—O3	144.16 (17)
C3—C4—C5—C6	0.0 (3)	C3—C2—N1—O3	−37.5 (2)
C4—C5—C6—O1	−178.25 (16)	C5—C6—O1—C7	−4.5 (3)
C4—C5—C6—C1	1.3 (3)	C1—C6—O1—C7	175.90 (18)

Symmetry codes: (i) −x+1, y, −z+3/2.

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7B···O3ii	0.96	2.48	3.426 (3)	169

Symmetry codes: (ii) x−1/2, y−1/2, z.