3-Picoline

The crystal structure of 3-picoline (3-methyl­pyridine, C₆H₇N) has been determined at 120 (2) K following in situ crystal growth from the liquid. The mol­ecules pack in a herring-bone-type arrangement in the non-centrosymmetric space group Pna2₁.

Key indicators

• Single-crystal X-ray study
• T = 120 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.040
• wR factor = 0.106
• Data-to-parameter ratio = 8.1

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           27.50
         From the CIF: _reflns_number_total                665
         Count of symmetry unique reflns          672
         Completeness (_total/calc)             98.96%
         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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S1. Comment

The picolines (methylpyridines) comprise a series of empirical formula C₆H₇N, with weak intermolecular interactions and low melting points. The crystal structure of 4-picoline (4-methylpyridine; m.p. 276 K) has been determined previously from a crystal grown using an elaborate modified Bridgman technique (Ohms et al., 1985). We report here the crystal structure of 3-picoline (m.p. 255 K), determined at 120 (2) K from a crystal grown in situ in a 0.3 mm glass capillary. This work forms part of a study devoted to improving techniques for determining the crystal structures of substances that are liquids at room temperature (see, for example, Bond & Davies, 2001).

Molecules of (I) (Fig. 1) pack in a herring-bone-type arrangement in the non-centrosymmetric space group Pna2₁ (Fig. 2). There are no apparent directional C—H···N interactions: the closest contacts to N1 are made by H4 and H5, with geometric parameters H4···N1ⁱ = 2.77 (3) Å and C4—H4···N1ⁱ = 124 (2)°, and H5···N1ⁱ = 2.90 (2) Å and C5—H5···N1ⁱ = 120 (2) Å [symmetry code: (i) 1.5 - x, 0.5 + y, 0.5 + z].

S2. Experimental

The sample (99%) was obtained from the Aldrich Company and was used without further purification. The crystal was grown in a 0.3 mm glass capillary tube at 240 K (a temperature only slightly less than the melting point of the solid in the capillary tube) using a technique described previously (Davies & Bond, 2001). The crystal was cooled subsequently to 120 (2) K for data collection. The length of the cylindrical crystal was not estimated, but it exceeded the 0.35 mm collimator diameter.

S3. Refinement

H atoms were placed geometrically and allowed to refine with independent isotropic displacement parameters (one common parameter for the methyl-H atoms). Friedel pairs (478) were merged prior to merging in Pna2₁; the reported value of R_int corresponds to subsequent merging of equivalent reflections in this space group.

Computing details

Data collection: COLLECT (Nonius, 1998); cell refinement: HKL and 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); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The molecular structure and atom-labelling scheme for (I) showing displacement ellipsoids at 50% probability for non-H atoms (XP; Sheldrick, 1993).
	Fig. 2. Projection of (I) onto (001) showing the herring-bone packing arrangement (CAMERON; Watkin et al., 1996).

3-methylpyridine

Crystal data

C6H7N	Dx = 1.172 Mg m^−3
Mr = 93.13	Melting point: 254.9 K
Orthorhombic, Pna21	Mo Kα radiation, λ = 0.7107 Å
a = 9.3516 (9) Å	Cell parameters from 3581 reflections
b = 9.7925 (10) Å	θ = 1.0–27.5°
c = 5.7651 (3) Å	µ = 0.07 mm^−1
V = 527.94 (8) Å^3	T = 120 K
Z = 4	Cylinder, colourless
F(000) = 200	0.15 mm (radius)

Data collection

Nonius KappaCCD diffractometer	Rint = 0.040
Radiation source: fine-focus sealed tube	θmax = 27.5°, θmin = 4.1°
Thin–slice ω and ϕ scans	h = −12→8
2718 measured reflections	k = −9→12
665 independent reflections	l = −6→7
643 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)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.106	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0633P)^2 + 0.0757P] where P = (Fo^2 + 2Fc^2)/3
665 reflections	(Δ/σ)max = 0.002
82 parameters	Δρmax = 0.17 e Å^−3
1 restraint	Δρmin = −0.16 e Å^−3

Special details

Experimental. Grown in situ in a 0.3 mm Lindemann capillary tube at 240 K. Freidel pairs (478) 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	0.81677 (17)	−0.01946 (16)	1.0686 (3)	0.0269 (4)
C2	0.70900 (19)	0.02815 (16)	0.9380 (3)	0.0231 (4)
H2	0.691 (3)	−0.016 (2)	0.789 (5)	0.028 (6)*
C3	0.62234 (17)	0.13911 (16)	0.9967 (3)	0.0211 (4)
C4	0.65209 (18)	0.20425 (18)	1.2061 (3)	0.0239 (4)
H4	0.597 (3)	0.286 (3)	1.247 (6)	0.042 (7)*
C5	0.7631 (2)	0.15703 (17)	1.3440 (4)	0.0263 (4)
H5	0.783 (2)	0.204 (2)	1.495 (5)	0.030 (6)*
C6	0.8417 (2)	0.04500 (19)	1.2694 (4)	0.0263 (5)
H6	0.919 (3)	0.011 (2)	1.358 (5)	0.043 (7)*
C7	0.5034 (2)	0.18534 (18)	0.8400 (4)	0.0286 (4)
H7A	0.4235	0.2191	0.9339	0.071 (6)*
H7B	0.4710	0.1084	0.7449	0.071 (6)*
H7C	0.5381	0.2587	0.7389	0.071 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0241 (7)	0.0239 (7)	0.0326 (9)	0.0023 (6)	0.0034 (7)	0.0003 (7)
C2	0.0247 (8)	0.0214 (8)	0.0231 (8)	−0.0018 (6)	0.0027 (8)	−0.0028 (7)
C3	0.0192 (7)	0.0201 (7)	0.0239 (8)	−0.0030 (6)	0.0012 (7)	0.0010 (7)
C4	0.0225 (8)	0.0216 (8)	0.0275 (10)	0.0009 (6)	0.0013 (8)	−0.0040 (7)
C5	0.0268 (9)	0.0249 (8)	0.0273 (9)	−0.0030 (7)	−0.0009 (8)	−0.0029 (10)
C6	0.0205 (8)	0.0266 (8)	0.0319 (11)	−0.0005 (6)	−0.0022 (7)	0.0026 (8)
C7	0.0254 (8)	0.0300 (8)	0.0304 (9)	0.0016 (7)	−0.0057 (8)	−0.0022 (9)

Geometric parameters (Å, º)

N1—C6	1.339 (3)	C3—C7	1.503 (3)
N1—C2	1.342 (2)	C4—C5	1.387 (3)
C2—C3	1.397 (2)	C5—C6	1.389 (3)
C3—C4	1.393 (2)
C6—N1—C2	116.88 (15)	C2—C3—C7	121.20 (17)
N1—C2—C3	124.75 (17)	C5—C4—C3	119.57 (16)
C4—C3—C2	116.75 (17)	C4—C5—C6	118.82 (19)
C4—C3—C7	122.05 (16)	N1—C6—C5	123.23 (18)