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The crystal structure of 2,5-lutidine (2,5-di­methyl­pyridine, C7H9N) has been determined at 150 (2) K following in situ crystal growth from the liquid. In space group P\overline 1, the asymmetric unit contains two independent mol­ecules. Mol­ecules are linked via C—H...N interactions into polar chains aligned in a parallel manner to form polar sheets. Adjacent sheets are packed in an anti-parallel arrangement.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802003380/cf6153sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536802003380/cf6153Isup2.hkl
Contains datablock I

CCDC reference: 182637

Key indicators

  • Single-crystal X-ray study
  • T = 150 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.054
  • wR factor = 0.145
  • Data-to-parameter ratio = 18.2

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry








Comment top

This work forms 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 crystal structures of 2,6-lutidine (Bond et al., 2001) and 3,5-lutidine (Bond & Davies, 2002), and report here the structure of the isomer 2,5-lutidine, (I), determined at 150 (2) K following in situ crystal growth from the liquid.

In space group P1, there are two independent molecules of (I) in the asymmetric unit (Fig. 1). Molecules are linked via C—H···N interactions into extended chains [Fig. 2; H4B···N1A = 2.66 Å, C4B—H4B···N1A = 159°; H4A···N1Bi = 2.63 Å and C4A—H4A···N1Bi = 157°; symmetry code: (i) x, y, -1 + z]. Similar chains are observed in the crystal structures of 2,6-lutidine and 3,5-lutidine. Within the chains in (I), adjacent molecules are twisted about the direction of chain propagation with an angle between the least-squares planes through adjacent molecules of 54.0 (1)°. This twist presumably accommodates the steric requirements of the methyl substituents. Adjacent chains are arranged in a parallel manner to give polar sheets parallel to (010) (Fig. 2). Chains in adjacent sheets are arranged in an anti-parallel manner so that the crystal is not macroscopically polar (Fig. 3).

Experimental top

The sample (99%) was obtained from the Lancaster company and used without further purification. The crystal was grown in a 0.3 mm glass capillary tube at ca 236 K (a temperature only slightly less than the melting point of the solid in the capillary tube) 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 collimator (0.35 mm).

Refinement top

H atoms were placed geometrically and refined with isotropic displacement parameters, with common parameters assigned to chemically equivalent H atoms (one parameter for all methyl H atoms, four parameters in total). Both methyl groups are disordered and were modelled as two sets of positions, each position rotated at 60° from the other about the local threefold axis.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO and SCALEPACK (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 asymmetric unit and atom-labelling scheme, showing displacement ellipsoids (C/N atoms) at the 50% probability level (XP; Sheldrick, 1993). Independent molecules are denoted by the suffixes A and B.
[Figure 2] Fig. 2. Projection on to (010) of a single layer of (I), showing polar chains linked by C—H···N interactions into polar sheets (CAMERON; Watkin et al., 1996).
[Figure 3] Fig. 3. Projection on to (100) showing layers of (I) arranged in an antiparallel manner (CAMERON; Watkin et al., 1996).
2,5-dimethylpyridine top
Crystal data top
C7H9NF(000) = 232
Mr = 107.15Dx = 1.113 Mg m3
Triclinic, P1Melting point: 258 K
a = 7.0991 (4) ÅMo Kα radiation, λ = 0.7107 Å
b = 7.7279 (5) ÅCell parameters from 2259 reflections
c = 12.3900 (9) Åθ = 1.0–22.5°
α = 108.139 (4)°µ = 0.07 mm1
β = 92.399 (4)°T = 150 K
γ = 96.743 (5)°Cylinder, colourless
V = 639.26 (7) Å30.15 mm (radius)
Z = 4
Data collection top
Nonius KappaCCD
diffractometer
Rint = 0.030
Radiation source: fine-focus sealed tubeθmax = 27.5°, θmin = 3.7°
Thin–slice ω and ϕ scansh = 09
4192 measured reflectionsk = 99
2827 independent reflectionsl = 1515
1643 reflections with I > 2σ(I)
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)] = 0.054Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.145H-atom parameters constrained
S = 1.03 w = 1/[σ2(Fo2) + (0.0487P)2 + 0.1043P]
where P = (Fo2 + 2Fc2)/3
2827 reflections(Δ/σ)max < 0.001
155 parametersΔρmax = 0.14 e Å3
0 restraintsΔρmin = 0.13 e Å3
Crystal data top
C7H9Nγ = 96.743 (5)°
Mr = 107.15V = 639.26 (7) Å3
Triclinic, P1Z = 4
a = 7.0991 (4) ÅMo Kα radiation
b = 7.7279 (5) ŵ = 0.07 mm1
c = 12.3900 (9) ÅT = 150 K
α = 108.139 (4)°0.15 mm (radius)
β = 92.399 (4)°
Data collection top
Nonius KappaCCD
diffractometer
1643 reflections with I > 2σ(I)
4192 measured reflectionsRint = 0.030
2827 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0540 restraints
wR(F2) = 0.145H-atom parameters constrained
S = 1.03Δρmax = 0.14 e Å3
2827 reflectionsΔρmin = 0.13 e Å3
155 parameters
Special details top

Experimental. Crystal grown in situ in a 0.3 mm Lindemann tube at 236 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.

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

2.5016 (0.0055) x + 6.8487 (0.0029) y - 3.1884 (0.0079) z = 5.0267 (0.0020)

* 0.0014 (0.0008) N1A * -0.0015 (0.0011) C2A * 0.0002 (0.0011) C3A * 0.0011 (0.0011) C4A * -0.0012 (0.0008) C5A

Rms deviation of fitted atoms = 0.0012

- 2.8000 (0.0048) x + 6.0639 (0.0036) y + 3.6076 (0.0076) z = 6.5009 (0.0039)

Angle to previous plane (with approximate e.s.d.) = 54.07 (0.05)

* -0.0029 (0.0008) N1B * 0.0034 (0.0011) C2B * -0.0010 (0.0010) C3B * -0.0018 (0.0011) C4B * 0.0023 (0.0008) C5B

Rms deviation of fitted atoms = 0.0024

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*/UeqOcc. (<1)
N1A0.25742 (19)0.81270 (19)0.37067 (12)0.0456 (4)
C2A0.4063 (2)0.7350 (2)0.32155 (15)0.0405 (4)
C3A0.4134 (2)0.6780 (2)0.20418 (15)0.0423 (4)
H3A0.51970.62400.17130.053 (2)*
C4A0.2674 (2)0.6995 (2)0.13545 (14)0.0399 (4)
H4A0.27260.66050.05510.053 (2)*
C5A0.1135 (2)0.7775 (2)0.18304 (14)0.0393 (4)
C6A0.1162 (2)0.8312 (2)0.30039 (15)0.0429 (4)
H6A0.01060.88510.33420.053 (2)*
C7A0.5634 (2)0.7155 (3)0.40036 (16)0.0541 (5)
H7AA0.51180.64060.44600.060 (2)*0.768 (18)
H7AB0.61880.83740.45100.060 (2)*0.768 (18)
H7AC0.66200.65580.35550.060 (2)*0.768 (18)
H7AD0.68330.78200.38900.060 (2)*0.232 (18)
H7AE0.57620.58510.38390.060 (2)*0.232 (18)
H7AF0.53310.76670.47950.060 (2)*0.232 (18)
C8A0.0512 (2)0.8010 (3)0.11044 (16)0.0562 (5)
H8AA0.00270.85360.05290.060 (2)*0.638 (17)
H8AB0.13090.88360.15870.060 (2)*0.638 (17)
H8AC0.12710.68110.07250.060 (2)*0.638 (17)
H8AD0.17120.75850.13650.060 (2)*0.362 (17)
H8AE0.04290.72860.03070.060 (2)*0.362 (17)
H8AF0.04670.93110.11690.060 (2)*0.362 (17)
N1B0.26955 (18)0.69075 (19)0.84937 (12)0.0430 (4)
C2B0.4229 (2)0.7806 (2)0.81909 (13)0.0358 (4)
C3B0.4128 (2)0.8328 (2)0.72224 (14)0.0401 (4)
H3B0.52250.89500.70220.053 (2)*
C4B0.2446 (2)0.7952 (2)0.65465 (14)0.0380 (4)
H4B0.23810.83130.58810.053 (2)*
C5B0.0858 (2)0.7052 (2)0.68387 (13)0.0368 (4)
C6B0.1067 (2)0.6566 (2)0.78164 (14)0.0409 (4)
H6B0.00190.59430.80270.053 (2)*
C7B0.6037 (2)0.8188 (2)0.89500 (15)0.0510 (5)
H7BA0.57740.78670.96400.060 (2)*0.593 (18)
H7BB0.65400.94950.91610.060 (2)*0.593 (18)
H7BC0.69750.74490.85440.060 (2)*0.593 (18)
H7BD0.70860.86740.85910.060 (2)*0.407 (18)
H7BE0.63190.70460.90690.060 (2)*0.407 (18)
H7BF0.58850.90920.96860.060 (2)*0.407 (18)
C8B0.1029 (2)0.6634 (2)0.61414 (15)0.0520 (5)
H8BA0.08710.69740.54490.060 (2)*0.627 (18)
H8BB0.19520.73380.65900.060 (2)*0.627 (18)
H8BC0.14900.53170.59330.060 (2)*0.627 (18)
H8BD0.20050.61120.65320.060 (2)*0.373 (18)
H8BE0.09240.57480.53910.060 (2)*0.373 (18)
H8BF0.13850.77690.60480.060 (2)*0.373 (18)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N1A0.0508 (8)0.0478 (8)0.0395 (9)0.0071 (6)0.0022 (7)0.0160 (7)
C2A0.0431 (8)0.0389 (9)0.0415 (10)0.0036 (7)0.0002 (7)0.0166 (8)
C3A0.0448 (8)0.0414 (9)0.0434 (11)0.0072 (7)0.0097 (8)0.0161 (8)
C4A0.0507 (9)0.0398 (9)0.0285 (9)0.0001 (7)0.0036 (7)0.0120 (7)
C5A0.0430 (8)0.0371 (9)0.0389 (10)0.0004 (7)0.0016 (7)0.0163 (7)
C6A0.0452 (9)0.0446 (10)0.0423 (11)0.0093 (7)0.0057 (8)0.0172 (8)
C7A0.0528 (10)0.0615 (12)0.0510 (12)0.0093 (9)0.0058 (9)0.0229 (10)
C8A0.0534 (10)0.0613 (12)0.0542 (13)0.0063 (9)0.0096 (9)0.0213 (10)
N1B0.0452 (7)0.0484 (8)0.0388 (9)0.0069 (6)0.0030 (6)0.0187 (7)
C2B0.0387 (8)0.0335 (8)0.0341 (9)0.0080 (6)0.0023 (7)0.0083 (7)
C3B0.0395 (8)0.0399 (9)0.0437 (11)0.0047 (7)0.0082 (7)0.0171 (8)
C4B0.0470 (8)0.0417 (9)0.0312 (9)0.0122 (7)0.0068 (7)0.0174 (7)
C5B0.0385 (8)0.0353 (9)0.0354 (10)0.0088 (7)0.0014 (7)0.0085 (7)
C6B0.0383 (8)0.0423 (9)0.0432 (11)0.0026 (7)0.0057 (7)0.0161 (8)
C7B0.0445 (9)0.0537 (11)0.0502 (12)0.0084 (8)0.0061 (8)0.0106 (9)
C8B0.0452 (9)0.0546 (11)0.0509 (12)0.0111 (8)0.0069 (8)0.0089 (9)
Geometric parameters (Å, º) top
N1A—C6A1.350 (2)N1B—C6B1.3489 (19)
N1A—C2A1.350 (2)N1B—C2B1.352 (2)
C2A—C3A1.387 (2)C2B—C3B1.382 (2)
C2A—C7A1.503 (2)C2B—C7B1.5018 (19)
C3A—C4A1.372 (2)C3B—C4B1.377 (2)
C3A—H3A0.950C3B—H3B0.950
C4A—C5A1.376 (2)C4B—C5B1.376 (2)
C4A—H4A0.950C4B—H4B0.950
C5A—C6A1.381 (2)C5B—C6B1.383 (2)
C5A—C8A1.508 (2)C5B—C8B1.5074 (19)
C6A—H6A0.950C6B—H6B0.950
C7A—H7AA0.980C7B—H7BA0.980
C7A—H7AB0.980C7B—H7BB0.980
C7A—H7AC0.980C7B—H7BC0.980
C7A—H7AD0.980C7B—H7BD0.980
C7A—H7AE0.980C7B—H7BE0.980
C7A—H7AF0.980C7B—H7BF0.980
C8A—H8AA0.980C8B—H8BA0.980
C8A—H8AB0.980C8B—H8BB0.980
C8A—H8AC0.980C8B—H8BC0.980
C8A—H8AD0.980C8B—H8BD0.980
C8A—H8AE0.980C8B—H8BE0.980
C8A—H8AF0.980C8B—H8BF0.980
C6A—N1A—C2A116.96 (15)C6B—N1B—C2B117.02 (15)
N1A—C2A—C3A121.25 (15)N1B—C2B—C3B121.16 (13)
N1A—C2A—C7A116.68 (16)N1B—C2B—C7B116.79 (15)
C3A—C2A—C7A122.06 (15)C3B—C2B—C7B122.05 (15)
C4A—C3A—C2A120.14 (15)C4B—C3B—C2B120.38 (15)
C4A—C3A—H3A119.9C4B—C3B—H3B119.8
C2A—C3A—H3A119.9C2B—C3B—H3B119.8
C3A—C4A—C5A119.91 (16)C5B—C4B—C3B119.72 (16)
C3A—C4A—H4A120.0C5B—C4B—H4B120.1
C5A—C4A—H4A120.0C3B—C4B—H4B120.1
C4A—C5A—C6A116.77 (15)C4B—C5B—C6B116.69 (14)
C4A—C5A—C8A121.58 (16)C4B—C5B—C8B121.98 (16)
C6A—C5A—C8A121.65 (15)C6B—C5B—C8B121.33 (15)
N1A—C6A—C5A124.96 (15)N1B—C6B—C5B125.02 (15)
N1A—C6A—H6A117.5N1B—C6B—H6B117.5
C5A—C6A—H6A117.5C5B—C6B—H6B117.5
C2A—C7A—H7AA109.5C2B—C7B—H7BA109.5
C2A—C7A—H7AB109.5C2B—C7B—H7BB109.5
H7AA—C7A—H7AB109.5H7BA—C7B—H7BB109.5
C2A—C7A—H7AC109.5C2B—C7B—H7BC109.5
H7AA—C7A—H7AC109.5H7BA—C7B—H7BC109.5
H7AB—C7A—H7AC109.5H7BB—C7B—H7BC109.5
C2A—C7A—H7AD109.5C2B—C7B—H7BD109.5
C2A—C7A—H7AE109.5C2B—C7B—H7BE109.5
H7AD—C7A—H7AE109.5H7BD—C7B—H7BE109.5
C2A—C7A—H7AF109.5C2B—C7B—H7BF109.5
H7AD—C7A—H7AF109.5H7BD—C7B—H7BF109.5
H7AE—C7A—H7AF109.5H7BE—C7B—H7BF109.5
C5A—C8A—H8AA109.5C5B—C8B—H8BA109.5
C5A—C8A—H8AB109.5C5B—C8B—H8BB109.5
H8AA—C8A—H8AB109.5H8BA—C8B—H8BB109.5
C5A—C8A—H8AC109.5C5B—C8B—H8BC109.5
H8AA—C8A—H8AC109.5H8BA—C8B—H8BC109.5
H8AB—C8A—H8AC109.5H8BB—C8B—H8BC109.5
C5A—C8A—H8AD109.5C5B—C8B—H8BD109.5
C5A—C8A—H8AE109.5C5B—C8B—H8BE109.5
H8AD—C8A—H8AE109.5H8BD—C8B—H8BE109.5
C5A—C8A—H8AF109.5C5B—C8B—H8BF109.5
H8AD—C8A—H8AF109.5H8BD—C8B—H8BF109.5
H8AE—C8A—H8AF109.5H8BE—C8B—H8BF109.5
C6A—N1A—C2A—C3A0.4 (2)C6B—N1B—C2B—C3B0.7 (2)
C6A—N1A—C2A—C7A179.80 (15)C6B—N1B—C2B—C7B179.83 (14)
N1A—C2A—C3A—C4A0.2 (3)N1B—C2B—C3B—C4B0.5 (2)
C7A—C2A—C3A—C4A179.60 (16)C7B—C2B—C3B—C4B179.92 (14)
C2A—C3A—C4A—C5A0.1 (2)C2B—C3B—C4B—C5B0.0 (2)
C3A—C4A—C5A—C6A0.1 (2)C3B—C4B—C5B—C6B0.3 (2)
C3A—C4A—C5A—C8A179.07 (15)C3B—C4B—C5B—C8B178.94 (14)
C2A—N1A—C6A—C5A0.3 (3)C2B—N1B—C6B—C5B0.5 (2)
C4A—C5A—C6A—N1A0.1 (3)C4B—C5B—C6B—N1B0.0 (2)
C8A—C5A—C6A—N1A179.26 (16)C8B—C5B—C6B—N1B179.19 (14)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C4B—H4B···N1A0.952.663.567 (2)159
C4A—H4A···N1Bi0.952.633.525 (2)157
Symmetry code: (i) x, y, z1.

Experimental details

Crystal data
Chemical formulaC7H9N
Mr107.15
Crystal system, space groupTriclinic, P1
Temperature (K)150
a, b, c (Å)7.0991 (4), 7.7279 (5), 12.3900 (9)
α, β, γ (°)108.139 (4), 92.399 (4), 96.743 (5)
V3)639.26 (7)
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
4192, 2827, 1643
Rint0.030
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.054, 0.145, 1.03
No. of reflections2827
No. of parameters155
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.14, 0.13

Computer programs: COLLECT (Nonius, 1998), HKL SCALEPACK (Otwinowski & Minor, 1997), HKL DENZO and SCALEPACK (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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