2,6-Lutidine

The crystal structure of 2,6-lutidine (2,6-di­methyl­pyridine, C₇H₉N), has been determined at 120 (2) K following in situ crystal growth from the liquid. In the non-centrosymmetric space group Fdd2, the asymmetric unit comprises half a mol­ecule, each mol­ecule being sited on a crystallographic diad axis. Molecules are linked via linear C—H...N interactions into one-dimensional chains that align in a parallel manner, giving rise to macroscopically polar crystals.

Key indicators

• Single-crystal X-ray study
• T = 120 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.057
• wR factor = 0.140
• Data-to-parameter ratio = 8.4

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           27.39
         From the CIF: _reflns_number_total                387
         Count of symmetry unique reflns          399
         Completeness (_total/calc)             96.99%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured         0
         Fraction of Friedel pairs measured     0.000
         Are heavy atom types Z>Si present           no
          Please check that the estimate of the number of Friedel pairs is
          correct. If it is not, please give the correct count in the
          _publ_section_exptl_refinement section of the submitted CIF.

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Computing details

Data collection: COLLECT (Nonius, 1998); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick,1997); software used to prepare material for publication: SHELXL97.

2,6-Dimethylpyridine

Crystal data

C7H9N	Dx = 1.104 Mg m^−3
Mr = 107.15	Melting point: 267 K
Orthorhombic, Fdd2	Mo Kα radiation, λ = 0.71073 Å
a = 13.782 (3) Å	Cell parameters from 1553 reflections
b = 14.805 (3) Å	θ = 1.0–27.5°
c = 6.317 (1) Å	µ = 0.07 mm^−1
V = 1288.9 (4) Å^3	T = 120 K
Z = 8	Cylinder, colourless
F(000) = 464	0.15 mm (radius)

Data collection

Nonius KappaCCD diffractometer	Rint = 0.034
Radiation source: fine-focus sealed tube	θmax = 27.4°, θmin = 3.8°
Thin–slice ω and φ scans	h = −17→13
1429 measured reflections	k = −19→15
387 independent reflections	l = −7→8
351 reflections with I > 2σ(I)

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)] = 0.057	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.140	H-atom parameters constrained
S = 1.11	w = 1/[σ^2(Fo^2) + (0.0788P)^2 + 0.8716P] where P = (Fo^2 + 2Fc^2)/3
387 reflections	(Δ/σ)max = 0.007
46 parameters	Δρmax = 0.22 e Å^−3
1 restraint	Δρmin = −0.18 e Å^−3

Special details

Experimental. Crystal grown in situ in a 0.3 mm Lindemann tube at 260 K. Absolute structure could not be determined and Friedel pairs (288) were averaged for the refinement.

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	0.0000	0.5000	0.0817 (4)	0.0299 (8)
C2	0.0155 (2)	0.57658 (18)	0.1892 (3)	0.0325 (8)
C3	0.0153 (2)	0.5788 (2)	0.4104 (4)	0.0359 (8)
H3	0.030 (3)	0.637 (2)	0.483 (6)	0.050 (11)*
C4	0.0000	0.5000	0.5226 (7)	0.0385 (11)
H4	0.0000	0.5000	0.665 (8)	0.026 (11)*
C7	0.0315 (2)	0.66065 (19)	0.0612 (6)	0.0459 (8)
H7A	0.0658	0.6453	−0.0698	0.078 (7)*
H7B	0.0704	0.7036	0.1432	0.078 (7)*
H7C	−0.0313	0.6880	0.0265	0.078 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0301 (14)	0.0398 (18)	0.0198 (19)	−0.0056 (13)	0.000	0.000
C2	0.0310 (17)	0.038 (2)	0.0286 (19)	−0.0029 (11)	−0.0009 (11)	0.0026 (11)
C3	0.0373 (19)	0.042 (2)	0.0280 (15)	0.0042 (11)	−0.0016 (12)	−0.0053 (12)
C4	0.039 (2)	0.053 (3)	0.024 (2)	0.0097 (17)	0.000	0.000
C7	0.0536 (16)	0.0422 (16)	0.0420 (18)	−0.0118 (12)	−0.0056 (17)	0.0076 (16)

Geometric parameters (Å, º)

N1—C2	1.339 (3)	C4—C3^i	1.381 (4)
N1—C2^i	1.339 (3)	C4—H4	0.90 (5)
C2—C3	1.397 (3)	C7—H7A	0.9800
C2—C7	1.500 (4)	C7—H7B	0.9800
C3—C4	1.381 (4)	C7—H7C	0.9800
C3—H3	1.00 (4)
C2—N1—C2^i	119.0 (3)	C3^i—C4—H4	120.9 (2)
N1—C2—C3	121.8 (3)	C3—C4—H4	120.9 (2)
N1—C2—C7	116.90 (19)	C2—C7—H7A	109.5
C3—C2—C7	121.3 (3)	C2—C7—H7B	109.5
C4—C3—C2	119.6 (3)	H7A—C7—H7B	109.5
C4—C3—H3	122 (2)	C2—C7—H7C	109.5
C2—C3—H3	118 (2)	H7A—C7—H7C	109.5
C3^i—C4—C3	118.2 (4)	H7B—C7—H7C	109.5
C2^i—N1—C2—C3	−0.5 (3)	C7—C2—C3—C4	179.8 (2)
C2^i—N1—C2—C7	−179.4 (3)	C2—C3—C4—C3^i	−0.4 (2)
N1—C2—C3—C4	0.9 (5)

Symmetry code: (i) −x, −y+1, z.