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The crystal structure of 3,5-lutidine (3,5-di­methyl­pyridine, C7H9N) has been determined at 150 (2) K following in situ crystal growth from the liquid. In space group I2/a, the asymmetric unit comprises half a mol­ecule, each mol­ecule possessing a crystallographic diad axis. Molecules are linked by linear C—H...N interactions into extended polar chains aligned in a parallel manner to form polar sheets. Adjacent sheets are arranged in an anti-parallel manner.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801020426/cf6133sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536801020426/cf6133Isup2.hkl
Contains datablock I

CCDC reference: 180526

Key indicators

  • Single-crystal X-ray study
  • T = 150 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.069
  • wR factor = 0.214
  • Data-to-parameter ratio = 19.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


Amber Alert Alert Level B:
RINTA_01 Alert B The value of Rint is greater than 0.15 Rint given 0.165
0 Alert Level A = Potentially serious problem
1 Alert Level B = Potential problem
0 Alert Level C = Please check

Comment top

As part of a study devoted to improving the techniques for determining the crystal structures of substances that are liquids at room temperature, we have reported previously the crystal structure of 2,6-lutidine (2,6-dimethylpyridine) (Bond et al., 2001). We report here the crystal structure of the isomeric molecule, 3,5-lutidine, (I), determined at 150 (2) K following in situ crystal growth from the liquid.

In space group I2/a, the asymmetric unit comprises half a molecule, each molecule possessing a crystallographic diad axis passing through N1 and C4 (Fig. 1). Molecules are linked via linear C—H···N interactions [C4–H4···N1i = 2.51 (3) Å and C4–H4···N1i = 180°; symmetry code: (i) x, 1 + y, z] into extended polar chains, similar to those observed in the crystal structure of 2,6-lutidine. All chains propagate parallel to [010], forming polar sheets (Fig. 2) parallel to (101). Chains in adjacent sheets are arranged in an anti-parallel manner (Fig. 3) so that the crystal is not macroscopically polar. This is in contrast to the structure of 2,6-lutidine in which a change in the position of the methyl substituents produces a macroscopically polar structure in space group Fdd2, where all sheets are arranged in a parallel fashion. This observation may be of interest to researchers seeking organic molecular materials for non-linear optic (NLO) applications.

Experimental top

The sample (99%) was obtained from the Aldrich Company and used without further purification. The crystal was grown in a 0.3 mm glass capillary tube at ca 256 K (a temperature only slightly less than the melting point of the solid in the capillary) using a technique described earlier (Davies & Bond, 2001). Once grown, the crystal was cooled to 150 (2) K for data collection. Although the diffraction pattern clearly contained contributions from more than one crystal (reflected to some extent in the relatively high Rint of 0.165), the pattern associated with the major crystal component was indexed successfully; only reflections associated with this component were included in the integration. The length of the cylindrical crystal was not estimated, but it exceeded the diameter of the collimator (0.35 mm).

Refinement top

The H atoms of the methyl group were placed geometrically, assigned one common isotropic displacement parameter and allowed to rotate about their local threefold axis. Other H atoms were refined independently with individual isotropic displacement parameters.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL SCALEPACK and DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Sheldrick, 1993) and CAMERON (Watkin et al., 1996); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The molecular structure and atom-labelling scheme for (I), showing displacement ellipsoids at the 50% probability level. Atoms related by the crystallographic diad axis are indicated by the suffix A (XP; Sheldrick, 1993).
[Figure 2] Fig. 2. Extended polar chains in (I), projected on to (101) (CAMERON; Watkin et al., 1996).
[Figure 3] Fig. 3. Projection of (I) parallel to the layers, showing the anti-parallel alignment of adjacent layers (CAMERON; Watkin et al., 1996).
3,5-dimethylpyridine top
Crystal data top
C7H9NDx = 1.113 Mg m3
Mr = 107.15Melting point: 264 K
Monoclinic, I2/aMo Kα radiation, λ = 0.7107 Å
a = 9.7236 (9) ÅCell parameters from 1914 reflections
b = 6.2851 (8) Åθ = 1.0–30.0°
c = 10.517 (2) ŵ = 0.07 mm1
β = 95.691 (5)°T = 150 K
V = 639.57 (16) Å3Cylinder, colourless
Z = 40.15 mm (radius)
F(000) = 232
Data collection top
Nonius KappaCCD
diffractometer
620 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.165
Graphite monochromatorθmax = 30.0°, θmin = 3.8°
Thin–slice ω and ϕ scansh = 1013
2651 measured reflectionsk = 88
912 independent reflectionsl = 1014
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.069Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.214H atoms treated by a mixture of independent and constrained refinement
S = 1.05 w = 1/[σ2(Fo2) + (0.1018P)2 + 0.203P]
where P = (Fo2 + 2Fc2)/3
912 reflections(Δ/σ)max < 0.001
46 parametersΔρmax = 0.21 e Å3
0 restraintsΔρmin = 0.22 e Å3
Crystal data top
C7H9NV = 639.57 (16) Å3
Mr = 107.15Z = 4
Monoclinic, I2/aMo Kα radiation
a = 9.7236 (9) ŵ = 0.07 mm1
b = 6.2851 (8) ÅT = 150 K
c = 10.517 (2) Å0.15 mm (radius)
β = 95.691 (5)°
Data collection top
Nonius KappaCCD
diffractometer
620 reflections with I > 2σ(I)
2651 measured reflectionsRint = 0.165
912 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0690 restraints
wR(F2) = 0.214H atoms treated by a mixture of independent and constrained refinement
S = 1.05Δρmax = 0.21 e Å3
912 reflectionsΔρmin = 0.22 e Å3
46 parameters
Special details top

Experimental. The crystal was grown in situ in a 0.3 mm Lindemann tube at ca 256 K.

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 (Å2) top
xyzUiso*/Ueq
N10.75000.1620 (3)1.00000.0464 (6)
C20.81964 (16)0.2733 (3)0.91918 (16)0.0404 (5)
H20.871 (3)0.193 (4)0.861 (2)0.072 (7)*
C30.82374 (14)0.4940 (2)0.91442 (13)0.0311 (5)
C40.75000.6042 (3)1.00000.0291 (5)
H40.75000.763 (5)1.00000.046 (7)*
C70.90627 (17)0.6065 (3)0.82106 (17)0.0429 (5)
H7A0.89300.76050.82800.095 (5)*
H7B0.87510.55990.73400.095 (5)*
H7C1.00450.57230.84040.095 (5)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0640 (13)0.0267 (9)0.0507 (12)0.0000.0167 (10)0.000
C20.0488 (9)0.0338 (9)0.0404 (9)0.0055 (6)0.0138 (7)0.0046 (6)
C30.0307 (7)0.0321 (8)0.0308 (7)0.0008 (5)0.0046 (5)0.0021 (5)
C40.0301 (10)0.0251 (10)0.0320 (10)0.0000.0033 (8)0.000
C70.0398 (9)0.0501 (10)0.0406 (9)0.0013 (6)0.0129 (7)0.0086 (7)
Geometric parameters (Å, º) top
N1—C2i1.3357 (19)C4—C3i1.3900 (17)
N1—C21.3357 (19)C4—H41.00 (3)
C2—C31.389 (2)C7—H7A0.980
C2—H20.97 (3)C7—H7B0.980
C3—C41.3900 (17)C7—H7C0.980
C3—C71.5047 (19)
C2i—N1—C2116.88 (19)C3—C4—H4119.90 (9)
N1—C2—C3124.33 (14)C3i—C4—H4119.90 (9)
N1—C2—H2117.3 (15)C3—C7—H7A109.5
C3—C2—H2118.4 (15)C3—C7—H7B109.5
C2—C3—C4117.13 (13)H7A—C7—H7B109.5
C2—C3—C7120.79 (13)C3—C7—H7C109.5
C4—C3—C7122.07 (14)H7A—C7—H7C109.5
C3—C4—C3i120.21 (18)H7B—C7—H7C109.5
C2i—N1—C2—C30.00 (11)C2—C3—C4—C3i0.00 (9)
N1—C2—C3—C40.0 (2)C7—C3—C4—C3i179.32 (14)
N1—C2—C3—C7179.33 (13)
Symmetry code: (i) x+3/2, y, z+2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C4—H4···N1ii1.00 (3)2.51 (3)3.506 (3)180
Symmetry code: (ii) x, y+1, z.

Experimental details

Crystal data
Chemical formulaC7H9N
Mr107.15
Crystal system, space groupMonoclinic, I2/a
Temperature (K)150
a, b, c (Å)9.7236 (9), 6.2851 (8), 10.517 (2)
β (°) 95.691 (5)
V3)639.57 (16)
Z4
Radiation typeMo Kα
µ (mm1)0.07
Crystal size (mm)0.15 (radius)
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
2651, 912, 620
Rint0.165
(sin θ/λ)max1)0.703
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.069, 0.214, 1.05
No. of reflections912
No. of parameters46
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.21, 0.22

Computer programs: COLLECT (Nonius, 1998), HKL SCALEPACK (Otwinowski & Minor, 1997), HKL SCALEPACK and DENZO (Otwinowski & Minor, 1997), SIR92 (Altomare et al., 1994), SHELXL97 (Sheldrick, 1997), XP (Sheldrick, 1993) and CAMERON (Watkin et al., 1996), SHELXL97.

 

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