Crystal structure of 2,6-di­chloro-4-nitro­pyridine N-oxide

In the title compound, C₅H₂Cl₂N₂O₃, the nitro group is essentially coplanar with the aromatic ring, with a twist angle of 4.00 (6)° and a fold angle of 2.28 (17)°. The crystal structure exhibits a herringbone pattern with the zigzag running along the b axis. The herringbone layer-to-layer distance is 3.0075 (15) Å, with a shift of 5.150 (4) Å. Neighboring mol­ecules are tilted at a 57.83 (4)° (ring-to-ring) angle with each other. The nitro group on one mol­ecule points to the N-oxide group on the neighboring one, with an inter­molecular O⋯N(nitro) distance of 3.1725 (13) Å.

1. Related literature

For the synthesis of the title compound and related compounds, see: Rousseau & Robins (1965). For chemical inter­est in derivatives of pyridine N-oxide, including the ruthenium-catalyzed use of these compounds towards the epoxidation of olefins via an N-oxide coordinated Ru^IV=O inter­mediate, see: Gross & Ini (1999).

2. Experimental

2.1. Crystal data

• C₅H₂Cl₂N₂O₃

• M_r = 208.99

• Orthorhombic, P b c a

• a = 5.964 (4) Å

• b = 9.510 (6) Å

• c = 26.192 (16) Å

• V = 1485.5 (16) ų

• Z = 8

• Mo Kα radiation

• μ = 0.84 mm⁻¹

• T = 173 K

• 0.6 × 0.2 × 0.1 mm

2.2. Data collection

• Rigaku XtaLAB mini diffractometer

• Absorption correction: multi-scan (REQAB; Rigaku, 1998) T_min = 0.709, T_max = 1.000

• 13695 measured reflections

• 1697 independent reflections

• 1512 reflections with I > 2σ(I)

• R_int = 0.043

2.3. Refinement

• R[F² > 2σ(F²)] = 0.032

• wR(F²) = 0.078

• S = 1.09

• 1697 reflections

• 109 parameters

• H-atom parameters constrained

• Δρ_max = 0.23 e Å⁻³

• Δρ_min = −0.34 e Å⁻³

Data collection: CrystalClear-SM Expert (Rigaku, 2011); cell refinement: CrystalClear-SM Expert; data reduction: CrystalClear-SM Expert; program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2.

Supporting information

S1. Synthesis and crystallization

2,6-Di­chloro-4-nitro­pyridine N-oxide was purchased from Sigma-Aldrich and 0.10 g was dissolved in approximately 50 mL of methanol. Diffraction quality crystals were obtained by slow evaporation of the solvent.

S2. Refinement

Carbon-bound H-atoms were placed in calculated positions (C—H = 0.95 Å) and were included in the refinement in the riding model approximation, with U_iso(H) set to 1.2U_equiv(C).

Related literature

For the synthesis of the title compound and related compounds, see: Rousseau & Robins (1965). Chemical interest in derivatives of pyridine N-oxide include the ruthenium-catalyzed use of these compounds towards the epoxidation of olefins via an N-oxide coordinated Ru^IV═ O intermediate, see: Gross & Ini (1999).

Computing details

Data collection: CrystalClear-SM Expert (Rigaku, 2011); cell refinement: CrystalClear-SM Expert (Rigaku, 2011); data reduction: CrystalClear-SM Expert (Rigaku, 2011); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Figures

Fig. 1. A view of the molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

2,6-Dichloro-4-nitropyridine N-oxide

Crystal data

C5H2Cl2N2O3	Dx = 1.869 Mg m^−3
Mr = 208.99	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 3422 reflections
a = 5.964 (4) Å	θ = 2.1–27.5°
b = 9.510 (6) Å	µ = 0.84 mm^−1
c = 26.192 (16) Å	T = 173 K
V = 1485.5 (16) Å^3	Prism, colorless
Z = 8	0.6 × 0.2 × 0.1 mm
F(000) = 832

Data collection

Rigaku XtaLAB mini diffractometer	1697 independent reflections
Radiation source: Sealed Tube	1512 reflections with I > 2σ(I)
Graphite Monochromator monochromator	Rint = 0.043
Detector resolution: 13.6612 pixels mm^-1	θmax = 27.5°, θmin = 3.1°
profile data from ω scans	h = −7→7
Absorption correction: multi-scan (REQAB; Rigaku, 1998)	k = −12→12
Tmin = 0.709, Tmax = 1.000	l = −33→34
13695 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.032	H-atom parameters constrained
wR(F^2) = 0.078	w = 1/[σ^2(Fo^2) + (0.026P)^2 + 0.628P] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max = 0.001
1697 reflections	Δρmax = 0.23 e Å^−3
109 parameters	Δρmin = −0.34 e Å^−3
0 restraints

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.

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

	x	y	z	Uiso*/Ueq
Cl2	0.85784 (8)	0.45634 (5)	0.29466 (2)	0.04219 (16)
Cl1	0.76404 (10)	0.58023 (6)	0.48666 (2)	0.05096 (18)
O1	0.9698 (2)	0.47138 (13)	0.39871 (5)	0.0406 (3)
O2	0.0755 (2)	0.79615 (14)	0.39133 (6)	0.0436 (3)
O3	0.1322 (2)	0.76147 (15)	0.31036 (6)	0.0494 (4)
N1	0.7830 (2)	0.53287 (14)	0.38874 (5)	0.0278 (3)
N2	0.1835 (2)	0.74825 (15)	0.35543 (6)	0.0337 (3)
C3	0.3887 (3)	0.67006 (16)	0.36721 (6)	0.0261 (3)
C4	0.5076 (3)	0.60983 (16)	0.32781 (6)	0.0273 (3)
H4	0.4563	0.6160	0.2935	0.033*
C2	0.4594 (3)	0.66162 (17)	0.41700 (7)	0.0297 (4)
H2	0.3734	0.7017	0.4439	0.036*
C5	0.7030 (3)	0.54043 (16)	0.33971 (6)	0.0268 (3)
C1	0.6574 (3)	0.59381 (17)	0.42689 (7)	0.0302 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl2	0.0471 (3)	0.0357 (3)	0.0438 (3)	0.0101 (2)	0.0179 (2)	0.00214 (18)
Cl1	0.0628 (4)	0.0529 (3)	0.0372 (3)	0.0068 (2)	−0.0209 (2)	−0.0034 (2)
O1	0.0271 (6)	0.0318 (7)	0.0630 (9)	0.0093 (5)	−0.0097 (6)	0.0019 (6)
O2	0.0319 (7)	0.0348 (7)	0.0639 (9)	0.0093 (6)	0.0106 (6)	0.0024 (6)
O3	0.0438 (8)	0.0493 (9)	0.0552 (9)	0.0111 (7)	−0.0184 (7)	0.0051 (7)
N1	0.0229 (7)	0.0207 (7)	0.0397 (8)	0.0013 (5)	−0.0042 (6)	0.0013 (6)
N2	0.0260 (7)	0.0242 (7)	0.0508 (9)	0.0009 (6)	−0.0035 (7)	0.0047 (6)
C3	0.0223 (7)	0.0202 (7)	0.0357 (9)	0.0005 (6)	−0.0006 (6)	0.0026 (6)
C4	0.0293 (8)	0.0223 (8)	0.0303 (8)	−0.0013 (6)	−0.0016 (7)	0.0021 (6)
C2	0.0325 (9)	0.0238 (8)	0.0330 (9)	0.0021 (7)	0.0018 (7)	−0.0019 (7)
C5	0.0281 (8)	0.0204 (8)	0.0319 (9)	0.0006 (6)	0.0045 (7)	0.0012 (6)
C1	0.0341 (9)	0.0255 (8)	0.0310 (9)	−0.0005 (7)	−0.0050 (7)	−0.0006 (6)

Geometric parameters (Å, º)

Cl2—C5	1.6984 (18)	N2—C3	1.465 (2)
Cl1—C1	1.695 (2)	C3—C4	1.377 (2)
O1—N1	1.2847 (18)	C3—C2	1.373 (2)
O2—N2	1.228 (2)	C4—H4	0.9500
O3—N2	1.226 (2)	C4—C5	1.375 (2)
N1—C5	1.372 (2)	C2—H2	0.9500
N1—C1	1.377 (2)	C2—C1	1.370 (3)
O1—N1—C5	121.03 (14)	C5—C4—H4	121.1
O1—N1—C1	121.06 (15)	C3—C2—H2	120.9
C5—N1—C1	117.90 (14)	C1—C2—C3	118.13 (16)
O2—N2—C3	117.74 (15)	C1—C2—H2	120.9
O3—N2—O2	124.65 (16)	N1—C5—Cl2	115.89 (13)
O3—N2—C3	117.61 (15)	N1—C5—C4	122.15 (15)
C4—C3—N2	118.91 (15)	C4—C5—Cl2	121.96 (14)
C2—C3—N2	119.10 (15)	N1—C1—Cl1	115.73 (13)
C2—C3—C4	121.98 (16)	C2—C1—Cl1	122.26 (14)
C3—C4—H4	121.1	C2—C1—N1	122.01 (16)
C5—C4—C3	117.79 (16)