Crystal structure of triclopyr.

In the title compound {systematic name: 2-[(3,5,6-tri-chloro-pyridin-2-yl)-oxy]acetic acid}, the herbicide triclopyr, C7H4Cl3NO3, the asymmetric unit comprises two independent mol-ecules in which the dihedral angles between the mean plane of the carb-oxy-lic acid group and the pyridyl ring plane are 79.3 (6) and 83.8 (5)°. In the crystal, pairs of inter-molecular O-H⋯O hydrogen bonds form dimers through an R 2 (2)(8) ring motif and are extended into chains along [100] by weak π-π inter-actions [ring centroid separations = 3.799 (4) and 3.810 (4) Å]. In addition, short inter-molecular Cl⋯Cl contacts [3.458 (2) Å] connect the chains, yielding a two-dimensional architecture extending parallel to (020). The crystal studied was found to be non-merohedrally twinned with the minor component being 0.175 (4).

Related literature

For information on the toxicity and herbicidal properties of the title compound, see: McMullin et al. (2011 ▶); Carney et al. (2007 ▶). For a related crystal structure, see: Smith et al. (1976 ▶). Non-merohedral twinning in the crystal was identified usinTwinRotMat within PLATON (Spek, 2009 ▶).

Experimental

Crystal data

C7H4Cl3NO3

M = 256.46

Monoclinic,

a = 7.5771 (9) Å

b = 25.409 (3) Å

c = 10.1668 (12) Å

β = 106.261 (8)°

V = 1879.1 (4) Å3

Z = 8

Mo Kα radiation

μ = 0.95 mm−1

T = 173 K

0.50 × 0.09 × 0.06 mm

Data collection

Bruker APEXII CCD diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T min = 0.648, T max = 0.945

3699 measured reflections

3699 independent reflections

3080 reflections with I > 2σ(I)

R int = 0.000

Refinement

R[F 2 > 2σ(F 2)] = 0.044

wR(F 2) = 0.096

S = 1.12

3699 reflections

256 parameters

H-atom parameters constrained

Δρmax = 0.32 e Å−3

Δρmin = −0.28 e Å−3

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: DIAMOND (Brandenburg, 2010 ▶); software used to prepare material for publication: SHELXTL.

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S160053681401681X/zs2309sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S160053681401681X/zs2309Isup2.hkl

Click here for additional data file.

Supporting information file. DOI: 10.1107/S160053681401681X/zs2309Isup3.cml

Click here for additional data file.

. DOI: 10.1107/S160053681401681X/zs2309fig1.tif

The asymmetric unit of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are shown as small spheres of arbitrary radius.

Click here for additional data file.

a . DOI: 10.1107/S160053681401681X/zs2309fig2.tif

Crystal packing viewed along the a axis. The inter­molecular O—H⋯O hydrogen bonds, weak π–π inter­actions, and short Cl⋯Cl contacts are shown as dashed lines.

CCDC reference: 1015180

Additional supporting information: crystallographic information; 3D view; checkCIF report

C7H4Cl3NO3	F(000) = 1024
Mr = 256.46	Dx = 1.813 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3761 reflections
a = 7.5771 (9) Å	θ = 2.2–25.5°
b = 25.409 (3) Å	µ = 0.95 mm−1
c = 10.1668 (12) Å	T = 173 K
β = 106.261 (8)°	Needle, colourless
V = 1879.1 (4) Å3	0.50 × 0.09 × 0.06 mm
Z = 8

Bruker APEXII CCD diffractometer	3699 independent reflections
Radiation source: fine-focus sealed tube	3080 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.000
φ and ω scans	θmax = 26.0°, θmin = 1.6°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −9→8
Tmin = 0.648, Tmax = 0.945	k = −31→31
3699 measured reflections	l = −5→12

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.096	H-atom parameters constrained
S = 1.12	w = 1/[σ2(Fo2) + (0.0219P)2 + 2.0682P] where P = (Fo2 + 2Fc2)/3
3699 reflections	(Δ/σ)max = 0.001
256 parameters	Δρmax = 0.32 e Å−3
0 restraints	Δρmin = −0.28 e Å−3

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.

	x	y	z	Uiso*/Ueq
Cl1	0.66278 (13)	0.53311 (3)	0.94222 (8)	0.0336 (2)
Cl2	0.86627 (14)	0.62564 (3)	1.13208 (9)	0.0397 (2)
Cl3	0.67175 (14)	0.75251 (3)	0.69082 (10)	0.0408 (2)
Cl4	1.00995 (14)	0.31553 (3)	0.50221 (9)	0.0380 (2)
Cl5	0.79593 (15)	0.23214 (3)	0.28102 (10)	0.0432 (3)
Cl6	0.66657 (14)	0.38875 (3)	−0.09150 (8)	0.0403 (2)
O1	0.4722 (3)	0.65825 (8)	0.5624 (2)	0.0317 (5)
O2	0.6886 (3)	0.58941 (10)	0.4787 (3)	0.0386 (6)
O3	0.4491 (3)	0.53970 (9)	0.3695 (3)	0.0382 (6)
H3O	0.5290	0.5231	0.3434	0.057*
O4	0.9075 (3)	0.44645 (8)	0.1341 (2)	0.0315 (5)
O5	0.9552 (3)	0.54570 (9)	0.3905 (2)	0.0316 (5)
H5O	0.8784	0.5599	0.4250	0.047*
O6	0.7219 (3)	0.49064 (9)	0.2971 (3)	0.0361 (6)
N1	0.5733 (4)	0.60258 (10)	0.7479 (3)	0.0248 (6)
N2	0.9432 (4)	0.38215 (10)	0.3000 (3)	0.0258 (6)
C1	0.6641 (4)	0.59584 (11)	0.8776 (3)	0.0242 (7)
C2	0.7565 (5)	0.63593 (12)	0.9613 (3)	0.0267 (7)
C3	0.7598 (5)	0.68502 (11)	0.9024 (3)	0.0278 (7)
H3	0.8254	0.7133	0.9552	0.033*
C4	0.6673 (5)	0.69213 (11)	0.7674 (3)	0.0254 (7)
C5	0.5714 (4)	0.64974 (12)	0.6938 (3)	0.0241 (7)
C6	0.3859 (5)	0.61313 (13)	0.4863 (3)	0.0331 (8)
H6A	0.2905	0.6247	0.4032	0.040*
H6B	0.3251	0.5920	0.5430	0.040*
C7	0.5265 (5)	0.57983 (12)	0.4455 (3)	0.0283 (7)
C8	0.9176 (5)	0.33276 (12)	0.3324 (3)	0.0266 (7)
C9	0.8219 (5)	0.29661 (12)	0.2378 (3)	0.0276 (7)
C10	0.7423 (5)	0.31367 (12)	0.1045 (3)	0.0279 (7)
H10	0.6717	0.2901	0.0376	0.033*
C11	0.7668 (5)	0.36496 (12)	0.0706 (3)	0.0266 (7)
C12	0.8738 (4)	0.39780 (11)	0.1722 (3)	0.0255 (7)
C13	1.0054 (5)	0.48192 (12)	0.2385 (3)	0.0301 (8)
H13A	1.0624	0.5100	0.1967	0.036*
H13B	1.1048	0.4627	0.3053	0.036*
C14	0.8768 (5)	0.50619 (12)	0.3117 (3)	0.0269 (7)

	U11	U22	U33	U12	U13	U23
Cl1	0.0447 (5)	0.0215 (4)	0.0343 (4)	−0.0055 (4)	0.0106 (4)	0.0039 (3)
Cl2	0.0511 (6)	0.0334 (4)	0.0276 (4)	−0.0038 (4)	−0.0006 (4)	0.0000 (3)
Cl3	0.0532 (6)	0.0246 (4)	0.0453 (5)	−0.0031 (4)	0.0153 (5)	0.0085 (4)
Cl4	0.0483 (6)	0.0327 (4)	0.0293 (4)	0.0081 (4)	0.0048 (4)	0.0055 (3)
Cl5	0.0617 (7)	0.0248 (4)	0.0466 (5)	−0.0052 (4)	0.0210 (5)	0.0019 (4)
Cl6	0.0517 (6)	0.0405 (5)	0.0244 (4)	0.0102 (4)	0.0035 (4)	0.0000 (3)
O1	0.0372 (14)	0.0290 (12)	0.0261 (12)	0.0025 (11)	0.0044 (11)	−0.0002 (9)
O2	0.0295 (15)	0.0436 (14)	0.0423 (15)	−0.0027 (12)	0.0092 (12)	−0.0138 (11)
O3	0.0304 (14)	0.0387 (14)	0.0430 (15)	−0.0022 (12)	0.0064 (12)	−0.0143 (11)
O4	0.0415 (15)	0.0223 (11)	0.0290 (12)	0.0005 (10)	0.0072 (11)	0.0008 (9)
O5	0.0290 (13)	0.0293 (12)	0.0355 (13)	−0.0032 (11)	0.0074 (11)	−0.0063 (10)
O6	0.0315 (15)	0.0296 (12)	0.0471 (15)	−0.0033 (11)	0.0110 (12)	−0.0094 (11)
N1	0.0244 (15)	0.0246 (13)	0.0270 (14)	−0.0031 (12)	0.0098 (12)	−0.0019 (11)
N2	0.0274 (16)	0.0230 (13)	0.0253 (14)	0.0030 (12)	0.0044 (12)	−0.0023 (11)
C1	0.0277 (18)	0.0185 (14)	0.0297 (17)	−0.0006 (13)	0.0136 (15)	0.0012 (12)
C2	0.0278 (19)	0.0281 (16)	0.0238 (16)	−0.0001 (14)	0.0066 (14)	−0.0012 (13)
C3	0.033 (2)	0.0186 (15)	0.0332 (18)	−0.0043 (14)	0.0117 (16)	−0.0043 (13)
C4	0.0314 (19)	0.0181 (14)	0.0301 (17)	0.0001 (14)	0.0141 (15)	0.0033 (12)
C5	0.0248 (18)	0.0252 (16)	0.0244 (16)	0.0021 (13)	0.0105 (14)	−0.0001 (12)
C6	0.031 (2)	0.0383 (19)	0.0274 (18)	0.0025 (16)	0.0038 (16)	−0.0071 (14)
C7	0.034 (2)	0.0296 (17)	0.0194 (16)	0.0003 (15)	0.0038 (15)	0.0009 (13)
C8	0.0269 (19)	0.0256 (16)	0.0279 (17)	0.0085 (14)	0.0089 (15)	0.0038 (13)
C9	0.0301 (19)	0.0227 (15)	0.0331 (18)	0.0020 (14)	0.0138 (16)	0.0015 (13)
C10	0.0268 (19)	0.0272 (16)	0.0305 (18)	−0.0004 (14)	0.0096 (15)	−0.0083 (13)
C11	0.0265 (18)	0.0297 (16)	0.0235 (16)	0.0066 (15)	0.0069 (15)	−0.0018 (13)
C12	0.0252 (18)	0.0210 (15)	0.0322 (18)	0.0063 (14)	0.0113 (15)	−0.0021 (13)
C13	0.032 (2)	0.0223 (15)	0.0353 (19)	−0.0010 (14)	0.0080 (16)	−0.0012 (14)
C14	0.031 (2)	0.0197 (15)	0.0267 (17)	0.0019 (15)	0.0028 (15)	0.0028 (13)

Cl1—C1	1.725 (3)	N2—C12	1.319 (4)
Cl2—C2	1.722 (3)	N2—C8	1.325 (4)
Cl3—C4	1.725 (3)	C1—C2	1.385 (4)
Cl4—C8	1.728 (3)	C2—C3	1.387 (4)
Cl5—C9	1.721 (3)	C3—C4	1.367 (4)
Cl6—C11	1.720 (3)	C3—H3	0.9500
O1—C5	1.354 (4)	C4—C5	1.394 (4)
O1—C6	1.434 (4)	C6—C7	1.507 (5)
O2—C7	1.204 (4)	C6—H6A	0.9900
O3—C7	1.314 (4)	C6—H6B	0.9900
O3—H3O	0.8400	C8—C9	1.379 (4)
O4—C12	1.341 (4)	C9—C10	1.389 (4)
O4—C13	1.431 (4)	C10—C11	1.374 (4)
O5—C14	1.318 (4)	C10—H10	0.9500
O5—H5O	0.8400	C11—C12	1.397 (4)
O6—C14	1.208 (4)	C13—C14	1.513 (5)
N1—C1	1.317 (4)	C13—H13A	0.9900
N1—C5	1.317 (4)	C13—H13B	0.9900
C5—O1—C6	116.6 (2)	O2—C7—O3	125.0 (3)
C7—O3—H3O	109.5	O2—C7—C6	123.6 (3)
C12—O4—C13	117.9 (2)	O3—C7—C6	111.3 (3)
C14—O5—H5O	109.5	N2—C8—C9	122.8 (3)
C1—N1—C5	118.6 (3)	N2—C8—Cl4	116.2 (2)
C12—N2—C8	119.0 (3)	C9—C8—Cl4	120.9 (2)
N1—C1—C2	123.5 (3)	C8—C9—C10	118.1 (3)
N1—C1—Cl1	116.4 (2)	C8—C9—Cl5	122.1 (3)
C2—C1—Cl1	120.1 (2)	C10—C9—Cl5	119.7 (2)
C1—C2—C3	117.6 (3)	C11—C10—C9	119.3 (3)
C1—C2—Cl2	121.7 (2)	C11—C10—H10	120.4
C3—C2—Cl2	120.7 (2)	C9—C10—H10	120.4
C4—C3—C2	119.1 (3)	C10—C11—C12	118.1 (3)
C4—C3—H3	120.5	C10—C11—Cl6	121.3 (3)
C2—C3—H3	120.5	C12—C11—Cl6	120.5 (2)
C3—C4—C5	118.7 (3)	N2—C12—O4	120.4 (3)
C3—C4—Cl3	120.1 (2)	N2—C12—C11	122.5 (3)
C5—C4—Cl3	121.2 (2)	O4—C12—C11	117.0 (3)
N1—C5—O1	119.7 (3)	O4—C13—C14	110.5 (3)
N1—C5—C4	122.4 (3)	O4—C13—H13A	109.6
O1—C5—C4	117.9 (3)	C14—C13—H13A	109.6
O1—C6—C7	110.3 (3)	O4—C13—H13B	109.6
O1—C6—H6A	109.6	C14—C13—H13B	109.6
C7—C6—H6A	109.6	H13A—C13—H13B	108.1
O1—C6—H6B	109.6	O6—C14—O5	125.5 (3)
C7—C6—H6B	109.6	O6—C14—C13	122.9 (3)
H6A—C6—H6B	108.1	O5—C14—C13	111.5 (3)
C5—N1—C1—C2	0.8 (5)	C12—N2—C8—C9	0.3 (5)
C5—N1—C1—Cl1	−179.5 (2)	C12—N2—C8—Cl4	−179.1 (2)
N1—C1—C2—C3	−3.1 (5)	N2—C8—C9—C10	−3.0 (5)
Cl1—C1—C2—C3	177.2 (2)	Cl4—C8—C9—C10	176.4 (2)
N1—C1—C2—Cl2	177.6 (3)	N2—C8—C9—Cl5	178.1 (3)
Cl1—C1—C2—Cl2	−2.1 (4)	Cl4—C8—C9—Cl5	−2.5 (4)
C1—C2—C3—C4	2.3 (5)	C8—C9—C10—C11	2.3 (5)
Cl2—C2—C3—C4	−178.4 (3)	Cl5—C9—C10—C11	−178.8 (3)
C2—C3—C4—C5	0.5 (5)	C9—C10—C11—C12	0.8 (5)
C2—C3—C4—Cl3	−179.1 (3)	C9—C10—C11—Cl6	−178.3 (2)
C1—N1—C5—O1	−177.0 (3)	C8—N2—C12—O4	−175.5 (3)
C1—N1—C5—C4	2.3 (5)	C8—N2—C12—C11	3.1 (5)
C6—O1—C5—N1	−4.9 (4)	C13—O4—C12—N2	−5.8 (4)
C6—O1—C5—C4	175.7 (3)	C13—O4—C12—C11	175.5 (3)
C3—C4—C5—N1	−3.0 (5)	C10—C11—C12—N2	−3.6 (5)
Cl3—C4—C5—N1	176.6 (2)	Cl6—C11—C12—N2	175.5 (2)
C3—C4—C5—O1	176.4 (3)	C10—C11—C12—O4	175.0 (3)
Cl3—C4—C5—O1	−4.1 (4)	Cl6—C11—C12—O4	−5.9 (4)
C5—O1—C6—C7	−75.3 (3)	C12—O4—C13—C14	−80.9 (3)
O1—C6—C7—O2	3.1 (5)	O4—C13—C14—O6	11.0 (4)
O1—C6—C7—O3	−176.7 (3)	O4—C13—C14—O5	−168.6 (2)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3O···O6	0.84	1.85	2.688 (3)	174
O5—H5O···O2	0.84	1.84	2.671 (3)	172

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3O⋯O6	0.84	1.85	2.688 (3)	174
O5—H5O⋯O2	0.84	1.84	2.671 (3)	172