Acta Cryst.(2002). E58, o961±o963 DOI: 10.1107/S1600536802013648 Bond and Davies C7H9N
o961
organic papers
Acta Crystallographica Section E Structure Reports Online
ISSN 1600-5368
2,3-Lutidine
Andrew D. Bond* and John E. Davies
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, England
Correspondence e-mail: [email protected]
Key indicators Single-crystal X-ray study T= 150 K
Mean(C±C) = 0.001 AÊ Disorder in main residue Rfactor = 0.050 wRfactor = 0.157
Data-to-parameter ratio = 33.3
For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.
#2002 International Union of Crystallography Printed in Great Britain ± all rights reserved
The crystal structure of 2,3-lutidine (2,3-dimethylpyridine, C7H9N) has been determined at 150 (2) K, following in situ
crystal growth from the liquid. Molecules are linked into polar chains via CÐH N interactions. The structure is best described as disordered in space group C2/c, with half a molecule in the asymmetric unit.
Comment
As part of a study devoted to improving the techniques for determining the crystal structures of substances that are liquid at room temperature, we have reported previously the struc-tures of all but one of the lutidine (dimethylpyridine) isomers (Bondet al., 2001; Bond & Davies, 2002a,b,c; Bond & Parsons, 2002). Reported here is the structure of the remaining isomer, 2,3-lutidine, (I), determined at 150 (2) K, following in situ crystal growth from the liquid.
In space groupC2/c, the asymmetric unit of (I) comprises half a molecule sited on a twofold axis that bisects the methyl-substituted positions and the opposite bond of the pyridine ring (Fig. 1). This leads to a disordered description of the structure in which the N atom and CÐH group in the 4-position are overlaid, with their site-occupancy factors constrained to be 0.5. Discounting the energetically unfa-vourable possibility of two N atoms in adjacent molecules being brought into close contact, and likewise two CÐH groups, the structure contains polar chains linked by CÐ H N interactions [H4 N1i = 2.55 AÊ, C4ÐH4 N1i =
162.0; symmetry code: (i)1
2ÿx,12ÿy,ÿz]. Similar chains are
observed in the 2,6-, 2,5- and 3,5-isomers. The chains in (I) are arranged in layers parallel to (101) (Fig. 2). The signi®cant distortion from linearity of the CÐH N interactions presumably accommodates the steric demands of the methyl substituents in adjacent chains. This disordered model suggests that chains are aligned in an antiparallel manner. It is not possible to comment de®nitively on the local nature of the alignment; adjacent chains within a given layer may always be parallel with their neighbours, but adjacent layers may be aligned in an antiparallel manner. Alternatively, there may be antiparallel alignment within layers, or even domains of parallel alignment distributed through the crystal.
organic papers
o962
Bond and Davies C7H9N Acta Cryst.(2002). E58, o961±o963An alternative description of the structure was examined in the polar space group Cc with a whole molecule in the asymmetric unit. This leads to a largely satisfactory re®nement withR[F2> 2(F2)] = 0.053 andwR(F2) = 0.149, although the
displacement ellipsoids of the N atom and the C atom in the 4-position of the ring appear slightly large and slightly small, respectively (Fig. 3). This is indicative of some disorder between the two positions,i.e.not all polar chains are aligned in a parallel manner. In view of this fact, and given that absolute structure determination is unfeasible, we believe that the disordered centrosymmetric model is most satisfactory.
Experimental
The sample (99%) was obtained from the Aldrich Co. and used without further puri®cation. The crystal was grown in a 0.3 mm glass capillary tube atca257.5 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. The length of the cylindrical crystal was not estimated, but it exceeded the diameter of the colli-mator (0.35 mm).
Crystal data
C7H9N
Mr= 107.15
Monoclinic,C2=c a= 11.4158 (7) AÊ
b= 7.5787 (5) AÊ
c= 7.4714 (4) AÊ
= 101.900 (4) V= 632.51 (7) AÊ3
Z= 4
Dx= 1.125 Mg mÿ3
MoKradiation Cell parameters from 3561
re¯ections
= 1.0±35.0
= 0.07 mmÿ1
T= 150 (2) K Cylinder, colourless 0.15 mm (radius)
Data collection
Nonius KappaCCD diffractometer Thin-slice!and'scans Absorption correction: none 2468 measured re¯ections 1366 independent re¯ections 1035 re¯ections withI> 2(I)
Rint= 0.023
max= 35.3
h=ÿ18!18
k=ÿ12!11
l=ÿ11!11
Re®nement
Re®nement onF2
R[F2> 2(F2)] = 0.050
wR(F2) = 0.157
S= 1.08 1366 re¯ections 41 parameters
H atoms treated by a mixture of independent and constrained re®nement
w= 1/[2(F
o2) + (0.0759P)2
+ 0.1323P]
whereP= (Fo2+ 2Fc2)/3
(/)max= 0.003
max= 0.36 e AÊÿ3
min=ÿ0.17 e AÊÿ3
Figure 2
View of (I), projected on to (101), showing a single layer of chains linked viaCÐH N interactions. Adjacent chains are shown arbitrarily to be coparallel.
Figure 3
The molecular unit and displacement ellipsoids (50% probability) for (I) in space groupCc. The large/small displacement parameters for N1 and C4 indicate that the structure is best described as disordered in space groupC2/c(seeComment).
Figure 1
All H atoms were placed geometrically and independent isotropic displacement parameters were re®ned (one common displacement parameter for the methyl H atoms). Each methyl group was allowed to rotate about its local threefold axis.
Data collection:COLLECT(Nonius, 1998); cell re®nement:HKL SCALEPACK(Otwinowski & Minor, 1997); data reduction:HKL DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure:SIR92 (Altomareet al., 1994); program(s) used to re®ne structure:SHELXL97 (Sheldrick, 1997); molecular graphics:XP(Sheldrick, 1993) andCAMERON(Watkinet al., 1996); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).
The authors thank the EPSRC for ®nancial assistance towards the purchase of the Nonius CCD diffractometer.
References
Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994).J. Appl. Cryst.27, 435.
Bond, A. D., Davies, J. E. & Kirby, A. J. (2001).Acta Cryst.E57, o1242±o1244. Bond, A. D. & Davies, J. E. (2002a).Acta Cryst.E58, o5±o7.
Bond, A. D. & Davies, J. E. (2002b).Acta Cryst.E58, o326±o327. Bond, A. D. & Davies, J. E. (2002c).Acta Cryst.E58, o328±o330. Bond, A. D. & Parsons, S. (2002).Acta Cryst.E58, o550±o552. Davies, J. E. & Bond, A. D. (2001).Acta Cryst.E57, o947±o949. Nonius (1998). Collect. Nonius BV, Delft, The Netherlands.
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276,
Macromolecular Crystallography, Part A, edited by C. W. Carter Jr and R. M. Sweet, pp. 307±326. New York: Academic Press.
Sheldrick, G. M. (1993).XP. University of GoÈttingen, Germany. Sheldrick, G. M. (1997).SHELXL97. University of GoÈttingen, Germany. Watkin, D. J., Prout, C. K. & Pearce, L. J. (1996).CAMERON. Chemical
Crystallography Laboratory, University of Oxford, England.
Acta Cryst.(2002). E58, o961±o963 Bond and Davies C7H9N
o963
supporting information
sup-1 Acta Cryst. (2002). E58, o961–o963
supporting information
Acta Cryst. (2002). E58, o961–o963 [https://doi.org/10.1107/S1600536802013648]
2,3-Lutidine
Andrew D. Bond and John E. Davies
2,3-dimethylpyridine
Crystal data
C7H9N Mr = 107.15 Monoclinic, C2/c a = 11.4158 (7) Å b = 7.5787 (5) Å c = 7.4714 (4) Å β = 101.900 (4)° V = 632.51 (7) Å3 Z = 4
F(000) = 232
Dx = 1.125 Mg m−3 Melting point: 258 K
Mo Kα radiation, λ = 0.7107 Å Cell parameters from 3561 reflections θ = 1.0–35.0°
µ = 0.07 mm−1 T = 150 K
Cylinder, colourless 0.15 mm (radius)
Data collection
Nonius KappaCCD diffractometer
Radiation source: fine-focus sealed tube Graphite monochromator
Thin–slice ω and φ scans 2468 measured reflections 1366 independent reflections
1035 reflections with I > 2σ(I) Rint = 0.023
θmax = 35.3°, θmin = 4.5° h = −18→18
k = −12→11 l = −11→11
Refinement
Refinement on F2 Least-squares matrix: full R[F2 > 2σ(F2)] = 0.050 wR(F2) = 0.157 S = 1.08 1366 reflections 41 parameters 0 restraints
Primary atom site location: structure-invariant direct methods
Secondary atom site location: difference Fourier map
Hydrogen site location: inferred from neighbouring sites
H atoms treated by a mixture of independent and constrained refinement
w = 1/[σ2(F
o2) + (0.0759P)2 + 0.1323P] where P = (Fo2 + 2Fc2)/3
(Δ/σ)max = 0.003 Δρmax = 0.36 e Å−3 Δρmin = −0.17 e Å−3
Special details
supporting information
sup-2 Acta Cryst. (2002). E58, o961–o963
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)
x y z Uiso*/Ueq Occ. (<1)
N1 0.38396 (7) 0.29005 (11) 0.15137 (11) 0.0379 (2) 0.50
C4 0.38396 (7) 0.29005 (11) 0.15137 (11) 0.0379 (2) 0.50
H4 0.3039 0.2892 0.0833 0.074 (3)* 0.50
C2 0.44100 (6) 0.44503 (9) 0.20050 (9) 0.02796 (19)
C6 0.44263 (10) 0.13626 (12) 0.20058 (14) 0.0492 (3)
H6 0.4034 0.0273 0.1658 0.078 (5)*
C7 0.37536 (9) 0.61430 (14) 0.14849 (13) 0.0464 (3)
H7C 0.2962 0.5888 0.0732 0.073 (2)*
H7B 0.4208 0.6877 0.0789 0.073 (2)*
H7A 0.3661 0.6772 0.2593 0.073 (2)*
Atomic displacement parameters (Å2)
U11 U22 U33 U12 U13 U23
N1 0.0329 (4) 0.0438 (5) 0.0339 (4) −0.0090 (3) −0.0003 (3) −0.0015 (3)
C4 0.0329 (4) 0.0438 (5) 0.0339 (4) −0.0090 (3) −0.0003 (3) −0.0015 (3)
C2 0.0272 (3) 0.0317 (4) 0.0250 (3) 0.0037 (2) 0.0057 (2) 0.0028 (2)
C6 0.0660 (6) 0.0320 (4) 0.0466 (5) −0.0152 (4) 0.0046 (4) −0.0043 (3)
C7 0.0528 (5) 0.0462 (5) 0.0431 (5) 0.0236 (4) 0.0164 (4) 0.0108 (4)
Geometric parameters (Å, º)
N1—C2 1.3564 (11) C6—H6 0.950
N1—C6 1.3567 (13) C7—H7C 0.980
C2—C2i 1.3966 (14) C7—H7B 0.980
C2—C7 1.4961 (11) C7—H7A 0.980
C6—C6i 1.365 (2)
C2—N1—C6 119.21 (8) C2—C7—H7C 109.5
N1—C2—C2i 120.00 (4) C2—C7—H7B 109.5
N1—C2—C7 119.04 (8) H7C—C7—H7B 109.5
C2i—C2—C7 120.95 (5) C2—C7—H7A 109.5
N1—C6—C6i 120.78 (5) H7C—C7—H7A 109.5
N1—C6—H6 119.6 H7B—C7—H7A 109.5
C6i—C6—H6 119.6
C6—N1—C2—C2i 0.43 (14) C2—N1—C6—C6i 0.45 (19)
C6—N1—C2—C7 −179.05 (8)
supporting information
sup-3 Acta Cryst. (2002). E58, o961–o963
Hydrogen-bond geometry (Å, º)
D—H···A D—H H···A D···A D—H···A
C4—H4···N1ii 0.95 2.55 3.4622 (14) 162
