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The crystal structure of 3,5-lutidine (3,5-dimethylpyridine, C
7H
9N) 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
CCDC reference: 180526
Key indicators
- Single-crystal X-ray study
- T = 150 K
- Mean (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
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
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).
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.
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.
Crystal data top
C7H9N | Dx = 1.113 Mg m−3 |
Mr = 107.15 | Melting point: 264 K |
Monoclinic, I2/a | Mo Kα radiation, λ = 0.7107 Å |
a = 9.7236 (9) Å | Cell parameters from 1914 reflections |
b = 6.2851 (8) Å | θ = 1.0–30.0° |
c = 10.517 (2) Å | µ = 0.07 mm−1 |
β = 95.691 (5)° | T = 150 K |
V = 639.57 (16) Å3 | Cylinder, colourless |
Z = 4 | 0.15 mm (radius) |
F(000) = 232 | |
Data collection top
Nonius KappaCCD diffractometer | 620 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.165 |
Graphite monochromator | θmax = 30.0°, θmin = 3.8° |
Thin–slice ω and ϕ scans | h = −10→13 |
2651 measured reflections | k = −8→8 |
912 independent reflections | l = −10→14 |
Refinement top
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)] = 0.069 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.214 | H 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 parameters | Δρmax = 0.21 e Å−3 |
0 restraints | Δρmin = −0.22 e Å−3 |
Crystal data top
C7H9N | V = 639.57 (16) Å3 |
Mr = 107.15 | Z = 4 |
Monoclinic, I2/a | Mo Kα radiation |
a = 9.7236 (9) Å | µ = 0.07 mm−1 |
b = 6.2851 (8) Å | T = 150 K |
c = 10.517 (2) Å | 0.15 mm (radius) |
β = 95.691 (5)° | |
Data collection top
Nonius KappaCCD diffractometer | 620 reflections with I > 2σ(I) |
2651 measured reflections | Rint = 0.165 |
912 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.069 | 0 restraints |
wR(F2) = 0.214 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | Δρmax = 0.21 e Å−3 |
912 reflections | Δρmin = −0.22 e Å−3 |
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 | x | y | z | Uiso*/Ueq | |
N1 | 0.7500 | 0.1620 (3) | 1.0000 | 0.0464 (6) | |
C2 | 0.81964 (16) | 0.2733 (3) | 0.91918 (16) | 0.0404 (5) | |
H2 | 0.871 (3) | 0.193 (4) | 0.861 (2) | 0.072 (7)* | |
C3 | 0.82374 (14) | 0.4940 (2) | 0.91442 (13) | 0.0311 (5) | |
C4 | 0.7500 | 0.6042 (3) | 1.0000 | 0.0291 (5) | |
H4 | 0.7500 | 0.763 (5) | 1.0000 | 0.046 (7)* | |
C7 | 0.90627 (17) | 0.6065 (3) | 0.82106 (17) | 0.0429 (5) | |
H7A | 0.8930 | 0.7605 | 0.8280 | 0.095 (5)* | |
H7B | 0.8751 | 0.5599 | 0.7340 | 0.095 (5)* | |
H7C | 1.0045 | 0.5723 | 0.8404 | 0.095 (5)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0640 (13) | 0.0267 (9) | 0.0507 (12) | 0.000 | 0.0167 (10) | 0.000 |
C2 | 0.0488 (9) | 0.0338 (9) | 0.0404 (9) | 0.0055 (6) | 0.0138 (7) | −0.0046 (6) |
C3 | 0.0307 (7) | 0.0321 (8) | 0.0308 (7) | 0.0008 (5) | 0.0046 (5) | 0.0021 (5) |
C4 | 0.0301 (10) | 0.0251 (10) | 0.0320 (10) | 0.000 | 0.0033 (8) | 0.000 |
C7 | 0.0398 (9) | 0.0501 (10) | 0.0406 (9) | −0.0013 (6) | 0.0129 (7) | 0.0086 (7) |
Geometric parameters (Å, º) top
N1—C2i | 1.3357 (19) | C4—C3i | 1.3900 (17) |
N1—C2 | 1.3357 (19) | C4—H4 | 1.00 (3) |
C2—C3 | 1.389 (2) | C7—H7A | 0.980 |
C2—H2 | 0.97 (3) | C7—H7B | 0.980 |
C3—C4 | 1.3900 (17) | C7—H7C | 0.980 |
C3—C7 | 1.5047 (19) | | |
| | | |
C2i—N1—C2 | 116.88 (19) | C3—C4—H4 | 119.90 (9) |
N1—C2—C3 | 124.33 (14) | C3i—C4—H4 | 119.90 (9) |
N1—C2—H2 | 117.3 (15) | C3—C7—H7A | 109.5 |
C3—C2—H2 | 118.4 (15) | C3—C7—H7B | 109.5 |
C2—C3—C4 | 117.13 (13) | H7A—C7—H7B | 109.5 |
C2—C3—C7 | 120.79 (13) | C3—C7—H7C | 109.5 |
C4—C3—C7 | 122.07 (14) | H7A—C7—H7C | 109.5 |
C3—C4—C3i | 120.21 (18) | H7B—C7—H7C | 109.5 |
| | | |
C2i—N1—C2—C3 | 0.00 (11) | C2—C3—C4—C3i | 0.00 (9) |
N1—C2—C3—C4 | 0.0 (2) | C7—C3—C4—C3i | −179.32 (14) |
N1—C2—C3—C7 | 179.33 (13) | | |
Symmetry code: (i) −x+3/2, y, −z+2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C4—H4···N1ii | 1.00 (3) | 2.51 (3) | 3.506 (3) | 180 |
Symmetry code: (ii) x, y+1, z. |
Experimental details
Crystal data |
Chemical formula | C7H9N |
Mr | 107.15 |
Crystal system, space group | Monoclinic, I2/a |
Temperature (K) | 150 |
a, b, c (Å) | 9.7236 (9), 6.2851 (8), 10.517 (2) |
β (°) | 95.691 (5) |
V (Å3) | 639.57 (16) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.07 |
Crystal size (mm) | 0.15 (radius) |
|
Data collection |
Diffractometer | Nonius KappaCCD diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2651, 912, 620 |
Rint | 0.165 |
(sin θ/λ)max (Å−1) | 0.703 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.069, 0.214, 1.05 |
No. of reflections | 912 |
No. of parameters | 46 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.21, −0.22 |
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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.