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The powder X-ray diffraction pattern of the crystalline phase of m-toluidine has been recorded with a sensitive curved detector (CPS120) at 150 K. The structure has been solved by real-space methods (simulated annealing) followed by Rietveld refinements with phenyl rings as rigid bodies and with soft constraints on bond lengths for peripheral atoms. The cell is monoclinic with space group P21/c and Z = 8. Equivalent molecules form chains along c. The crystalline cohesion is achieved by N—H...N hydrogen bonds between neighbouring chains of non-equivalent molecules and by van der Waals interactions of neighbouring chains of equivalent molecules. The hydrogen-bonding network has been confirmed by lattice-energy minimization. Anisotropic strain effects of the cell have been calculated. The directions of the minimal strains correspond to the directions of the hydrogen bonds. An explanation of the difficulty to crystallize the metastable phase is given.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0021889804006478/pd5008sup1.cif
Contains datablocks global, meta-toluidine

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0021889804006478/pd5008sup2.rtv
Contains datablock powder

CCDC reference: 254345

Experimental top

Liquid m-toluidine is commercially available (Aldrich Chemical Company) with a purity rate of 99%. Contacts with air or light easily induce an oxidation which gives rise to a typical brown-coloured compound. Furtherpurifications are necessary and they consist of two stages removal of organic and inorganic impurities. The compound is then distilled under low pressure, in order to get a colourless compound. A cold-nitrogen blower (Cryostream Oxford Cryosystem) allowed to access to low temperatures with temperature fluctuations within 0.5 K and was used for the in situ crystallization according to the following procedure. The liquid m-toluidine is quenched at 130 K by laying the cold stream on the capillary. After the temperature stabilization, the sample is heated until 220 K with an heating rate of 6 K/min. It is kept at this temperature during about 15 h in order to get a complete crystallization of the powder. Finally, the sample is cooled at the experiment temperature.

Refinement top

To determine the lattice parameters of m-toluidine at 150 K, the automatic powder indexing program N-TREOR (Altomare et al., 2000) implanted on EXPO (Altomare et al., 1999) has first been used. With the 25 first reflections of the pattern, no solution was found, suspecting the possibility of several phases in the powder. With the program WinPlotr (Roisnel & Rodriguez-Carvajal, 2002), the profiles of the 38 reflections with a 2-theta angle lower than 36 degrees were individually refined with a pseudo-Voigt function in order to obtain their 2? positions. The 2-theta angles of the 15 more intense reflections are introduced in the program TREOR (Werner et al., 1985) and these lines are completely indexed with a monoclinic cell with the following parameters: a = 24.815, b = 5.799, c = 8.743 A, beta = 100.03 degrees, V = 1238.8 A3. The calculated figures of merit are: M(15) = 31, F(15) = 43. (0.038, 94) (de Wolff, 1968; Smith & Snyder, 1979). It is to notice that the relation between the lattice parameters 2a cos(beta) + c = 0 is nearly verified leading to a pseudo-B-faced orthorhombic cell. As a consequence, the two reflections in the monoclinic cell (h, k, l) and (-h-l, k, l), with h and l > 0, have approximately the same d-spacing. The powder diffraction pattern from 12 to 72 degrees 2-theta, was subsequently refined with this cell and resolution constraints in the monoclinic space group P2/m (a space group without systematic extinctions) using the "profile matching" option [Le Bail et al. (1988), profile refinement] of the program FullProf (Rodriguez-Carvajal, 2001). Five lines with low intensity are not indexed with the previous cell and they can correspond to a second phase due to an impurity (Fig. 1). With the program TREOR, it is possible to find a monoclinic cell with these five reflections, but, it seems more realistic to remove regions of the pattern corresponding to these reflections (about 0.20 degree 2-theta around the maximum of the peaks) to avoid to introduce this cell in the refinements. A possibility of chemical for this impurity is the m-nitrotoluene resulting from the oxidation of the amine group of m-toluidine.

Computing details top

Data collection: PEAKOC; program(s) used to solve structure: FOX; program(s) used to refine structure: FULLPROF; molecular graphics: ORTEP-3; software used to prepare material for publication: SHELX97 and PARST.

Figures top
[Figure 1]
[Figure 2]
[Figure 3]
[Figure 4]
[Figure 5]
Figure 1: The 4 more intense Bragg reflections due to an impurity. Dots correspond to observed data, the upper solid line is the calculated profile for m-toluidine and the lower line is the difference between observed and calculated pattern. The fine vertical bars indicate the position of Bragg peaks for m-toluidine and the thick ones for the impurity. Figure 2: Final Rietveld plot of m-toluidine at 150 K. Observed data points are indicated by dots, the best-fit profile (upper trace) and the difference pattern (lower trace) are solid lines. The vertical bars correspond to the position of Bragg peaks. Figure 3: Atomic numbering and molecular structure of m-toluidine at 150 K. The dashed bond represents the hydrogen bond between the two molecules of the asymmetric unit. Figure 4: Projection of the unit cell of m-toluidine along b. For the sake of clarity, H atoms have been omitted. Dashed lines correspond to hydrogen bonds and the arrows show the direction of the N—H···N bonds. Figure 5: Calculated strain in the monoclinic plane of m-toluidine at 150 K.
3-methylbenzenamine top
Crystal data top
C7H9NF(000) = 464
Mr = 107.16Dx = 1.142 Mg m3
Monoclinic, P21/CMelting point: 232 K
Hall symbol: -P 2ybcCu Kα radiation, λ = 1.540560 Å
a = 24.8727 (6) ŵ = 0.52 mm1
b = 5.80729 (17) ÅT = 150 K
c = 8.7615 (3) Åwhite
β = 100.0624 (17)°cylinder, diameter 0.7 mm, ? × ? × ? mm
V = 1246.07 (7) Å3Specimen preparation: Prepared at 220 K K
Z = 8
Data collection top
Enraf Nonius FR 590
diffractometer
Data collection mode: transmission
Radiation source: Sealed X-ray tubeScan method: Stationary detector
Quartz (Curved Monochromator) monochromatorAbsorption correction: for a cylinder mounted on the ϕ axis
?
Specimen mounting: Lindemann Glass CapillaryTmin = ?, Tmax = ?
Refinement top
Rp = 3.499Profile function: Pseudo-Voigt
Rwp = 5.04492 parameters
Rexp = 1.2938 restraints
RBragg = 4.039
χ2 = NOT FOUNDBackground function: linear interpolation between 34 points
3946 data pointsPreferred orientation correction: March-Dollase function, axis [0,0,1], G1=0.914(3), G2=0
Excluded region(s): 0.29 to 12.0 : bad calibration of the CPS120 90.0 to 120.0 : peak intensities too low 18.55 to 18.95, 19.50 to 19.80, 21.10 to 21.45 and 23.20 to 23.60 : presence of peaks due to an impurity
Crystal data top
C7H9NV = 1246.07 (7) Å3
Mr = 107.16Z = 8
Monoclinic, P21/CCu Kα radiation, λ = 1.540560 Å
a = 24.8727 (6) ŵ = 0.52 mm1
b = 5.80729 (17) ÅT = 150 K
c = 8.7615 (3) Åcylinder, diameter 0.7 mm, ? × ? × ? mm
β = 100.0624 (17)°
Data collection top
Enraf Nonius FR 590
diffractometer
Scan method: Stationary detector
Specimen mounting: Lindemann Glass CapillaryAbsorption correction: for a cylinder mounted on the ϕ axis
?
Data collection mode: transmissionTmin = ?, Tmax = ?
Refinement top
Rp = 3.499χ2 = NOT FOUND
Rwp = 5.0443946 data points
Rexp = 1.29392 parameters
RBragg = 4.0398 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C110.9127 (3)0.0803 (8)0.3811 (6)0.026 (2)*
C120.8827 (3)0.2258 (8)0.4613 (6)0.026 (2)*
C130.8320 (3)0.1557 (8)0.4916 (6)0.026 (2)*
C140.8112 (3)0.0600 (8)0.4420 (6)0.026 (2)*
C150.8412 (3)0.2057 (8)0.3620 (6)0.026 (2)*
C160.8919 (3)0.1355 (8)0.3315 (6)0.026 (2)*
C170.9646 (4)0.2014 (19)0.3508 (18)0.026 (2)*
N10.7997 (5)0.2785 (13)0.5758 (14)0.026 (2)*
H120.89730.37730.49610.026 (2)*
H140.77560.10920.46340.026 (2)*
H150.82660.35710.32710.026 (2)*
H160.91300.23790.27520.026 (2)*
H1710.98850.21630.45030.026 (2)*
H1720.98030.10000.27940.026 (2)*
H1730.95320.34900.30320.026 (2)*
HN110.769 (3)0.244 (16)0.636 (10)0.026 (2)*
HN120.815 (3)0.426 (7)0.541 (8)0.026 (2)*
C210.5874 (3)0.0995 (8)0.4826 (6)0.034 (2)*
C220.6227 (3)0.2046 (8)0.6037 (6)0.034 (2)*
C230.6707 (3)0.0933 (8)0.6718 (6)0.034 (2)*
C240.6833 (3)0.1231 (8)0.6186 (6)0.034 (2)*
C250.6479 (3)0.2284 (8)0.4975 (6)0.034 (2)*
C260.6000 (3)0.1171 (8)0.4296 (6)0.034 (2)*
C270.5337 (4)0.1961 (19)0.3934 (15)0.034 (2)*
N20.7026 (3)0.231 (2)0.7874 (9)0.034 (2)*
H220.61390.35680.64100.034 (2)*
H240.71690.20130.66640.034 (2)*
H250.65670.38040.46020.034 (2)*
H260.57510.19100.34440.034 (2)*
H2710.53250.35860.42270.034 (2)*
H2720.53460.17540.28380.034 (2)*
H2730.50440.10710.42750.034 (2)*
HN210.692 (3)0.248 (15)0.893 (4)0.034 (2)*
HN220.742 (10)0.215 (17)0.782 (11)0.034 (2)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
???????
Geometric parameters (Å, º) top
C17—C111.534 (14)C27—C211.531 (12)
C17—H1710.970C27—H2710.980
C17—H1720.987C27—H2720.977
C17—H1730.974C27—H2730.982
N1—C131.380 (13)N2—C231.420 (11)
N1—HN111.01 (8)N2—HN211.01 (5)
N1—HN121.01 (6)N2—HN221.01 (3)
C11—C17—H171106.7H271—C27—H273111.7
C11—C17—H172105.8H272—C27—H273112.4
H171—C17—H172112.1C23—N2—HN21120 (3)
C11—C17—H173106.5C23—N2—HN22110 (3)
H171—C17—H173113.2HN21—N2—HN22118 (4)
H172—C17—H173111.9C12—C11—C17110.5 (6)
C13—N1—HN11137 (4)C16—C11—C17129.4 (4)
C13—N1—HN1289 (4)N1—C13—C12125.6 (8)
HN11—N1—HN12133 (6)N1—C13—C14114.3 (5)
C21—C27—H271106.5C22—C21—C27127.2 (7)
C21—C27—H272106.9C26—C21—C27112.8 (6)
H271—C27—H272112.6C24—C23—N2128.1 (6)
C21—C27—H273106.3C22—C23—N2111.9 (6)
C17—C11—C12—C13175.6 (7)C27—C21—C22—C23179.2 (8)
C17—C11—C16—C15174.7 (8)C27—C21—C26—C25179.4 (7)
C11—C12—C13—N1176.7 (8)C21—C22—C23—N2177.1 (7)
N1—C13—C14—C15177.0 (7)N2—C23—C24—C25176.7 (7)
HN11—N1—C13—C12158 (7)HN21—N2—C23—C2276 (5)
HN11—N1—C13—C1419 (7)HN21—N2—C23—C24107 (5)
HN12—N1—C13—C1230 (4)HN22—N2—C23—C22140 (5)
HN12—N1—C13—C14153 (4)HN22—N2—C23—C2436 (5)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—HN11···N21.01 (8)2.30 (8)3.302 (15)170 (6)
N2—HN22···N1i1.01 (3)2.71 (3)3.176 (13)108 (3)
Symmetry code: (i) x, y1/2, z+1/2.

Experimental details

Crystal data
Chemical formulaC7H9N
Mr107.16
Crystal system, space groupMonoclinic, P21/C
Temperature (K)150
a, b, c (Å)24.8727 (6), 5.80729 (17), 8.7615 (3)
β (°) 100.0624 (17)
V3)1246.07 (7)
Z8
Radiation typeCu Kα, λ = 1.540560 Å
µ (mm1)0.52
Specimen shape, size (mm)Cylinder, diameter 0.7 mm, ? × ? × ?
Data collection
DiffractometerEnraf Nonius FR 590
diffractometer
Specimen mountingLindemann Glass Capillary
Data collection modeTransmission
Scan methodStationary detector
2θ values (°)2θfixed = ?
Refinement
R factors and goodness of fitRp = 3.499, Rwp = 5.044, Rexp = 1.293, RBragg = 4.039, χ2 = NOT FOUND
No. of data points3946
No. of parameters92
No. of restraints8

Computer programs: PEAKOC, FOX, FULLPROF, ORTEP-3, SHELX97 and PARST.

Selected geometric parameters (Å, º) top
C17—C111.534 (14)C27—C211.531 (12)
N1—C131.380 (13)N2—C231.420 (11)
N1—HN111.01 (8)N2—HN211.01 (5)
N1—HN121.01 (6)N2—HN221.01 (3)
C13—N1—HN11137 (4)C16—C11—C17129.4 (4)
C13—N1—HN1289 (4)N1—C13—C12125.6 (8)
HN11—N1—HN12133 (6)N1—C13—C14114.3 (5)
C23—N2—HN21120 (3)C22—C21—C27127.2 (7)
C23—N2—HN22110 (3)C26—C21—C27112.8 (6)
HN21—N2—HN22118 (4)C24—C23—N2128.1 (6)
C12—C11—C17110.5 (6)C22—C23—N2111.9 (6)
C17—C11—C12—C13175.6 (7)C27—C21—C22—C23179.2 (8)
C17—C11—C16—C15174.7 (8)C27—C21—C26—C25179.4 (7)
C11—C12—C13—N1176.7 (8)C21—C22—C23—N2177.1 (7)
N1—C13—C14—C15177.0 (7)N2—C23—C24—C25176.7 (7)
HN11—N1—C13—C12158 (7)HN21—N2—C23—C2276 (5)
HN11—N1—C13—C1419 (7)HN21—N2—C23—C24107 (5)
HN12—N1—C13—C1230 (4)HN22—N2—C23—C22140 (5)
HN12—N1—C13—C14153 (4)HN22—N2—C23—C2436 (5)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—HN11···N21.01 (8)2.30 (8)3.302 (15)170 (6)
N2—HN22···N1i1.01 (3)2.71 (3)3.176 (13)108 (3)
Symmetry code: (i) x, y1/2, z+1/2.
 

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