Bis(4-meth­­oxy­pyridin-3-yl)diazene

The asymmetric unit of the title compound, C₁₂H₁₂N₄O₂, consists of one half-mol­ecule, which is located on a center of inversion. The molecule has a step-like shape; the azo group adopting a trans configuration, with the pyridine rings being parallel-displace.

Related literature

For background to this work, see: Thies et al. (2010, 2011); Venkataramani et al. (2011).

Experimental

Crystal data

• C₁₂H₁₂N₄O₂

• M_r = 244.26

• Orthorhombic, P b c a

• a = 13.3976 (8) Å

• b = 6.2101 (6) Å

• c = 13.6079 (9) Å

• V = 1132.18 (15) ų

• Z = 4

• Mo Kα radiation

• μ = 0.10 mm⁻¹

• T = 220 K

• 0.3 × 0.2 × 0.2 mm

Data collection

• Stoe IPDS-1 diffractometer

• 5829 measured reflections

• 1235 independent reflections

• 1002 reflections with I > 2σ(I)

• R_int = 0.045

Refinement

• R[F² > 2σ(F²)] = 0.039

• wR(F²) = 0.105

• S = 1.04

• 1235 reflections

• 84 parameters

• H-atom parameters constrained

• Δρ_max = 0.26 e Å⁻³

• Δρ_min = −0.19 e Å⁻³

Data collection: X-AREA (Stoe & Cie, 2008); cell refinement: X-AREA; data reduction: X-RED32; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.

Supporting information

S1. Comment

We recently reported about a change of the spin state by association/dissociation of photodissociable ligands (PDL's) at square planar Ni(II) porphyrine complexes (Thies et al. 2010, Thies et al. 2011, Venkataramani et al., 2011). Within this project the title compound was synthesized as potential PDL and its structure was determined by single-crystal X-ray diffraction.

In the crystal structure of the title compound, the azo group is in a trans configuration with an torsion angle C2—N2—N2ⁱ—C2ⁱ (i = -x + 1, -y + 2, -z + 1) of 180° due to symmetry. The pyridine rings are not coplanar with the central C—N—N—C unit with torsion angles of 32.9 (2)° for C1—C2—N2—N2ⁱ and 151.5 (2)° for C3—C2—N2—N2ⁱ (i = -x + 1, -y + 2, -z + 1).

Related literature

For background to this work, see: Thies et al. (2010, 2011); Venkataramani et al. (2011).

S2. Experimental

3-Nitro-4-methoxypyridine (1.14 g, 7.41 mmol) was dissolved in ethanol (30 ml) and heated to 80°C. Barium hydroxide (3.50 g, 20.8 mmol) dissolved in 20 ml hot water was added. Zinc powder (6.00 g, 91,7 mmol) was added in small portions within 20 min. The reaction mixture was stirred at 80 °C for 3 h and filtered over celite®. 200 ml dichloromethane were added to the filtrate and air was bubbled through the solution for 2 h. The organic layer was dried over magnesium sulfate and the solvent was removed under reduced pressure. The crude product was dissolved in ethanol and two spoons of activated charcoal were added. After stirring at 80°C for 20 min the mixture was filtered over celite® and the product was crystallized from ethyl acetate. An orange solid (120 mg, 0.49 mmol, 13.2%) was afforded (mp: 218.4 °C). ¹H-NMR (500 MHz, 300 K, CDCl₃, TMS)): δ = 8.58 (s, 2H, 2-H), 8.55 (d, J = 5.8 Hz, 2H, 6-H), 7.02 (d, J = 5.8 Hz, 2H, 5-H), 4.08 (s, 6H, OCH₃) p.p.m.. IR (KBr): ν (cm^-1) = 2993, 2951, 1562, 1485, 1461, 1442, 1301, 1272, 1014, 817, 762. MS (EI): m/z (%) = 244 (100) [M]⁺, 136 (66) [M-PyrOMe]⁺, 108 (77) [M-NNPyrOMe]⁺. MS (CI): m/z (%) = 245 (100) [M+H]⁺. Anal. Calc.: C₁₂H₁₂N₄O₂ (244.10), ber. C 59.01, H 4.95, N 22.94, gef. C 59.72, H 4.58, N 22.64%.

S3. Refinement

All H atoms were positioned with idealized geometry (methyl H atoms allowed to rotate but not to tip) and were refined isotropically with U_iso(H) = 1.2 U_eq(C) for aromatic H atoms (1.5 for methyl H atoms) using a riding model.

Computing details

Data collection: X-AREA (Stoe & Cie, 2008); cell refinement: X-AREA (Stoe & Cie, 2008); data reduction: X-RED32 (Stoe & Cie, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

Fig. 1. : Crystal structure of the title compound with labeling and displacement ellipsoids drawn at the 50% probability level. Symmetry code: i = -x + 1, -y + 2, -z + 1.

Bis(4-methoxypyridin-3-yl)diazene

Crystal data

C12H12N4O2	Dx = 1.433 Mg m^−3
Mr = 244.26	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 4972 reflections
a = 13.3976 (8) Å	θ = 4.7–28.8°
b = 6.2101 (6) Å	µ = 0.10 mm^−1
c = 13.6079 (9) Å	T = 220 K
V = 1132.18 (15) Å^3	Block, colourless
Z = 4	0.3 × 0.2 × 0.2 mm
F(000) = 512

Data collection

Stoe IPDS-1 diffractometer	1002 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.045
Graphite monochromator	θmax = 27.1°, θmin = 3.0°
Phi scans	h = −17→12
5829 measured reflections	k = −7→7
1235 independent reflections	l = −17→17

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.039	H-atom parameters constrained
wR(F^2) = 0.105	w = 1/[σ^2(Fo^2) + (0.0625P)^2 + 0.204P] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max < 0.001
1235 reflections	Δρmax = 0.26 e Å^−3
84 parameters	Δρmin = −0.19 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.030 (8)

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
N1	0.66974 (9)	0.6358 (2)	0.34371 (9)	0.0314 (3)
C1	0.62249 (10)	0.7907 (2)	0.39360 (9)	0.0263 (3)
H1	0.6591	0.9134	0.4119	0.032*
C2	0.52211 (9)	0.7811 (2)	0.42010 (8)	0.0211 (3)
C3	0.46546 (10)	0.60269 (19)	0.38987 (8)	0.0205 (3)
C4	0.51423 (10)	0.4414 (2)	0.33786 (9)	0.0250 (3)
H4	0.4794	0.3190	0.3161	0.030*
C5	0.61506 (11)	0.4644 (2)	0.31870 (10)	0.0301 (3)
H5	0.6475	0.3513	0.2857	0.036*
N2	0.47208 (8)	0.94965 (17)	0.47068 (7)	0.0228 (3)
O1	0.36924 (7)	0.60036 (15)	0.41627 (7)	0.0277 (3)
C6	0.30947 (11)	0.4230 (2)	0.38338 (11)	0.0321 (4)
H6A	0.3032	0.4284	0.3124	0.048*
H6B	0.2438	0.4320	0.4130	0.048*
H6C	0.3410	0.2888	0.4024	0.048*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0230 (6)	0.0348 (6)	0.0364 (7)	−0.0008 (5)	0.0067 (5)	−0.0042 (5)
C1	0.0237 (7)	0.0271 (7)	0.0280 (6)	−0.0044 (5)	0.0010 (5)	−0.0020 (5)
C2	0.0227 (6)	0.0202 (6)	0.0203 (5)	0.0000 (5)	−0.0014 (4)	−0.0006 (4)
C3	0.0200 (6)	0.0208 (6)	0.0205 (6)	0.0011 (5)	−0.0014 (4)	0.0011 (4)
C4	0.0273 (7)	0.0216 (6)	0.0261 (6)	−0.0009 (5)	−0.0004 (5)	−0.0045 (5)
C5	0.0292 (7)	0.0283 (7)	0.0329 (7)	0.0039 (6)	0.0052 (5)	−0.0058 (5)
N2	0.0231 (5)	0.0202 (5)	0.0251 (5)	−0.0017 (4)	−0.0012 (4)	−0.0022 (4)
O1	0.0193 (5)	0.0241 (5)	0.0396 (6)	−0.0030 (4)	0.0020 (4)	−0.0086 (4)
C6	0.0230 (7)	0.0288 (7)	0.0444 (8)	−0.0068 (6)	−0.0037 (6)	−0.0068 (6)

Geometric parameters (Å, º)

N1—C5	1.3360 (19)	C4—C5	1.3832 (19)
N1—C1	1.3369 (18)	C4—H4	0.9400
C1—C2	1.3936 (18)	C5—H5	0.9400
C1—H1	0.9400	N2—N2^i	1.260 (2)
C2—C3	1.4044 (17)	O1—C6	1.4333 (16)
C2—N2	1.4209 (16)	C6—H6A	0.9700
C3—O1	1.3384 (16)	C6—H6B	0.9700
C3—C4	1.3897 (17)	C6—H6C	0.9700
C5—N1—C1	116.29 (12)	C3—C4—H4	120.6
N1—C1—C2	123.89 (12)	N1—C5—C4	124.74 (13)
N1—C1—H1	118.1	N1—C5—H5	117.6
C2—C1—H1	118.1	C4—C5—H5	117.6
C1—C2—C3	118.65 (11)	N2^i—N2—C2	113.10 (14)
C1—C2—N2	123.30 (11)	C3—O1—C6	117.56 (10)
C3—C2—N2	117.91 (11)	O1—C6—H6A	109.5
O1—C3—C4	125.58 (11)	O1—C6—H6B	109.5
O1—C3—C2	116.77 (11)	H6A—C6—H6B	109.5
C4—C3—C2	117.62 (12)	O1—C6—H6C	109.5
C5—C4—C3	118.73 (12)	H6A—C6—H6C	109.5
C5—C4—H4	120.6	H6B—C6—H6C	109.5

Symmetry code: (i) −x+1, −y+2, −z+1.