Intermolecular interactions and unexpected isostructurality in the crystal structures of the dichlorobenzaldehyde isomers

The crystal structures of the six dichlorobenzaldehyde isomers, four of them newly determined, are analyzed in terms of the geometry and energies of their intermolecular interactions, quantified using the semi-classical density sums (SCDS-PIXEL) method. A consistent feature in all six structures is molecular stacks propagating along a short crystallographic axis of ca 3.8 Å. The stacks have a closely comparable geometry in each isomer, but the interaction energies between stacked molecules are variable on account of the differing relative positions of the Cl substituents. In the majority of the isomers the stacking interactions are the most stabilizing in the structure. Exceptions are the 2,4- and 3,5-isomers, where more stabilizing interactions are made between stacks. In general, the most stabilizing non-stacking intermolecular interactions in the structures are those involving C—H...O contacts. Observed motifs based on Cl...Cl interactions appear to be largely imposed by the constraints of other more stabilizing intermolecular interactions. The isomeric series displays the following noteworthy features: (i) the 2,3- and 2,6-isomers are isostructural despite having different orientations of the Cl and aldehyde functionalities; (ii) the 2,5-isomer exhibits whole-molecule disorder; (iii) the 2,5- and 3,5-isomers have more than one molecule in the crystallographic asymmetric unit (Z′ > 1). These features in particular are considered on the basis of the intermolecular interaction energies.

Computing details

For all compounds, data collection: APEX2 v.1.0-22 (Bruker Nonius, 2004); cell refinement: SAINT v.7.06a (Bruker, 2003); data reduction: SAINT v.7.06a; program(s) used to solve structure: SHELXTL v.6.10 (Sheldrick, 2000); program(s) used to refine structure: SHELXTL v.6.10; molecular graphics: SHELXTL v.6.10; software used to prepare material for publication: SHELXTL v.6.10.

Figures

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Crystal data

C7H4Cl2O	F(000) = 352
Mr = 175.00	Dx = 1.708 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3550 reflections
a = 3.7888 (3) Å	θ = 3.0–24.8°
b = 13.7784 (15) Å	µ = 0.87 mm^−1
c = 13.0368 (15) Å	T = 120 K
β = 90.979 (5)°	Needle, colourless
V = 680.47 (12) Å^3	0.30 × 0.05 × 0.05 mm
Z = 4

Data collection

Bruker-Nonius X8APEX-II CCD diffractometer	1226 independent reflections
Radiation source: fine-focus sealed tube	1036 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.049
thin–slice ω and ϕ scans	θmax = 25.3°, θmin = 4.3°
Absorption correction: multi-scan SADABS v.2.10 (Sheldrick, 2003) Ratio of minimum to maximum apparent transmission: 0.751021	h = −4→4
Tmin = 0.751, Tmax = 1.000	k = −16→16
11531 measured reflections	l = −15→15

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)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.093	H-atom parameters constrained
S = 1.13	w = 1/[σ^2(Fo^2) + (0.0365P)^2 + 1.0914P] where P = (Fo^2 + 2Fc^2)/3
1226 reflections	(Δ/σ)max < 0.001
91 parameters	Δρmax = 0.63 e Å^−3
0 restraints	Δρmin = −0.38 e Å^−3

Special details

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
Cl2	0.69778 (19)	0.85196 (5)	0.44125 (6)	0.0198 (2)
Cl3	0.61767 (19)	0.62727 (5)	0.41170 (6)	0.0195 (2)
O1	1.2820 (6)	0.94542 (15)	0.70410 (17)	0.0261 (5)
C1	1.0117 (7)	0.8087 (2)	0.6253 (2)	0.0156 (6)
C2	0.8454 (7)	0.7735 (2)	0.5366 (2)	0.0146 (6)
C3	0.8030 (7)	0.6735 (2)	0.5238 (2)	0.0152 (6)
C4	0.9164 (7)	0.6105 (2)	0.5996 (2)	0.0171 (6)
H4	0.8815	0.5427	0.5911	0.021*
C5	1.0795 (8)	0.6449 (2)	0.6872 (2)	0.0193 (7)
H5	1.1586	0.6008	0.7387	0.023*
C6	1.1285 (7)	0.7437 (2)	0.7003 (2)	0.0175 (6)
H6	1.2424	0.7673	0.7608	0.021*
C7	1.0775 (8)	0.9139 (2)	0.6411 (2)	0.0208 (7)
H7	0.9509	0.9587	0.5990	0.025*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl2	0.0238 (4)	0.0155 (4)	0.0200 (4)	0.0005 (3)	−0.0032 (3)	0.0045 (3)
Cl3	0.0218 (4)	0.0172 (4)	0.0195 (4)	−0.0008 (3)	−0.0034 (3)	−0.0029 (3)
O1	0.0359 (13)	0.0165 (11)	0.0258 (13)	−0.0021 (10)	−0.0086 (10)	−0.0033 (9)
C1	0.0142 (14)	0.0136 (14)	0.0191 (16)	−0.0004 (11)	0.0025 (12)	−0.0009 (12)
C2	0.0137 (14)	0.0153 (14)	0.0147 (15)	0.0024 (11)	0.0012 (11)	0.0045 (12)
C3	0.0138 (14)	0.0150 (15)	0.0169 (15)	−0.0018 (11)	0.0001 (11)	−0.0024 (12)
C4	0.0194 (15)	0.0127 (14)	0.0193 (16)	0.0000 (12)	0.0031 (12)	0.0005 (12)
C5	0.0191 (15)	0.0172 (15)	0.0216 (17)	0.0010 (12)	0.0002 (12)	0.0050 (12)
C6	0.0175 (14)	0.0185 (15)	0.0166 (16)	−0.0011 (12)	0.0004 (12)	−0.0019 (12)
C7	0.0227 (16)	0.0169 (16)	0.0229 (17)	0.0007 (13)	0.0020 (13)	−0.0006 (13)

Geometric parameters (Å, º)

Cl2—C2	1.734 (3)	C3—C4	1.378 (4)
Cl3—C3	1.732 (3)	C4—C5	1.373 (4)
O1—C7	1.201 (4)	C4—H4	0.950
C1—C6	1.392 (4)	C5—C6	1.385 (4)
C1—C2	1.394 (4)	C5—H5	0.950
C1—C7	1.485 (4)	C6—H6	0.950
C2—C3	1.397 (4)	C7—H7	0.950
C6—C1—C2	119.5 (3)	C3—C4—H4	119.7
C6—C1—C7	118.6 (3)	C4—C5—C6	120.0 (3)
C2—C1—C7	121.8 (3)	C4—C5—H5	120.0
C1—C2—C3	119.5 (3)	C6—C5—H5	120.0
C1—C2—Cl2	120.9 (2)	C5—C6—C1	120.3 (3)
C3—C2—Cl2	119.6 (2)	C5—C6—H6	119.8
C4—C3—C2	120.1 (3)	C1—C6—H6	119.8
C4—C3—Cl3	119.4 (2)	O1—C7—C1	123.6 (3)
C2—C3—Cl3	120.5 (2)	O1—C7—H7	118.2
C5—C4—C3	120.6 (3)	C1—C7—H7	118.2
C5—C4—H4	119.7
C6—C1—C2—C3	−0.9 (4)	C2—C3—C4—C5	−1.6 (4)
C7—C1—C2—C3	177.4 (3)	Cl3—C3—C4—C5	176.9 (2)
C6—C1—C2—Cl2	−179.8 (2)	C3—C4—C5—C6	0.5 (4)
C7—C1—C2—Cl2	−1.4 (4)	C4—C5—C6—C1	0.3 (4)
C1—C2—C3—C4	1.7 (4)	C2—C1—C6—C5	−0.1 (4)
Cl2—C2—C3—C4	−179.4 (2)	C7—C1—C6—C5	−178.5 (3)
C1—C2—C3—Cl3	−176.7 (2)	C6—C1—C7—O1	14.9 (4)
Cl2—C2—C3—Cl3	2.2 (3)	C2—C1—C7—O1	−163.5 (3)

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Crystal data

C7H4Cl2O	Z = 3
Mr = 175.00	F(000) = 264
Triclinic, P1	Dx = 1.656 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 3.8150 (5) Å	Cell parameters from 1343 reflections
b = 7.8290 (11) Å	θ = 2.9–24.1°
c = 17.895 (3) Å	µ = 0.84 mm^−1
α = 89.091 (5)°	T = 120 K
β = 85.728 (5)°	Needle, colourless
γ = 81.115 (5)°	0.35 × 0.03 × 0.03 mm
V = 526.60 (13) Å^3

Data collection

Bruker-Nonius X8APEX-II CCD diffractometer	1827 independent reflections
Radiation source: fine-focus sealed tube	1313 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.047
thin–slice ω and ϕ scans	θmax = 25.1°, θmin = 4.3°
Absorption correction: multi-scan SADABS v.2.10 (Sheldrick, 2003) Ratio of minimum to maximum apparent transmission: 0.721852	h = −4→4
Tmin = 0.704, Tmax = 0.975	k = −9→9
6319 measured reflections	l = −21→20

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)] = 0.037	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.081	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0339P)^2] where P = (Fo^2 + 2Fc^2)/3
1827 reflections	(Δ/σ)max < 0.001
145 parameters	Δρmax = 0.41 e Å^−3
0 restraints	Δρmin = −0.30 e Å^−3

Special details

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	Occ. (<1)
O1	0.2055 (5)	1.2310 (2)	0.18353 (11)	0.0278 (5)
C1	0.0282 (7)	0.9539 (3)	0.18013 (16)	0.0159 (7)
C2	−0.1146 (7)	0.8213 (4)	0.21890 (16)	0.0162 (7)
Cl2	−0.30351 (19)	0.85462 (10)	0.31062 (4)	0.0255 (2)
C3	−0.1086 (7)	0.6606 (3)	0.18701 (17)	0.0183 (7)
H3	−0.2003	0.5710	0.2149	0.022*
C4	0.0317 (7)	0.6327 (4)	0.11464 (17)	0.0190 (7)
H4	0.0347	0.5236	0.0920	0.023*
C5	0.1685 (7)	0.7627 (3)	0.07462 (15)	0.0141 (7)
Cl5	0.34316 (19)	0.72875 (9)	−0.01745 (4)	0.0196 (2)
C6	0.1683 (7)	0.9211 (4)	0.10660 (16)	0.0167 (7)
H6	0.2644	1.0091	0.0784	0.020*
C7	0.0427 (8)	1.1240 (4)	0.21324 (17)	0.0215 (7)
H7	−0.0827	1.1511	0.2605	0.026*
O1A	0.0815 (13)	0.9457 (5)	0.5114 (3)	0.0444 (13)	0.50
C7A	0.2594 (15)	0.8383 (8)	0.5478 (3)	0.0272 (16)	0.50
H7A	0.3169	0.8724	0.5955	0.033*	0.50
H4A	0.3142	0.7827	0.5433	0.033*	0.50
C1A	0.3878 (7)	0.6681 (4)	0.52552 (17)	0.0208 (7)
C2A	0.5752 (7)	0.5422 (4)	0.57071 (16)	0.0209 (7)
Cl2A	0.6697 (2)	0.59588 (10)	0.66033 (4)	0.0281 (2)
C3A	0.6859 (7)	0.3776 (4)	0.54496 (17)	0.0214 (7)
H3A	0.8143	0.2943	0.5759	0.026*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0415 (14)	0.0172 (11)	0.0262 (13)	−0.0113 (10)	0.0022 (11)	−0.0015 (10)
C1	0.0165 (16)	0.0139 (16)	0.0168 (17)	−0.0006 (13)	−0.0031 (14)	0.0028 (13)
C2	0.0107 (16)	0.0236 (17)	0.0139 (17)	−0.0006 (13)	−0.0034 (13)	0.0044 (13)
Cl2	0.0262 (5)	0.0317 (5)	0.0187 (5)	−0.0070 (4)	0.0022 (4)	0.0043 (3)
C3	0.0161 (17)	0.0152 (16)	0.0244 (19)	−0.0045 (13)	−0.0036 (14)	0.0082 (14)
C4	0.0196 (17)	0.0123 (16)	0.0265 (19)	−0.0041 (13)	−0.0074 (15)	0.0004 (13)
C5	0.0121 (16)	0.0142 (15)	0.0156 (17)	−0.0006 (12)	−0.0021 (13)	0.0010 (13)
Cl5	0.0244 (4)	0.0167 (4)	0.0179 (4)	−0.0044 (3)	0.0003 (3)	−0.0001 (3)
C6	0.0133 (16)	0.0164 (16)	0.0206 (18)	−0.0027 (13)	−0.0038 (14)	0.0070 (13)
C7	0.0226 (18)	0.0171 (17)	0.0236 (19)	0.0014 (14)	−0.0022 (15)	0.0007 (14)
O1A	0.056 (4)	0.017 (3)	0.056 (4)	0.012 (3)	−0.018 (3)	−0.003 (3)
C7A	0.037 (4)	0.015 (4)	0.029 (4)	−0.005 (3)	0.002 (3)	−0.003 (3)
C1A	0.0169 (17)	0.0193 (17)	0.0262 (19)	−0.0054 (14)	0.0035 (15)	0.0047 (14)
C2A	0.0152 (16)	0.0254 (18)	0.0223 (18)	−0.0066 (14)	0.0032 (14)	0.0065 (14)
Cl2A	0.0245 (5)	0.0387 (5)	0.0218 (5)	−0.0074 (4)	−0.0022 (4)	0.0042 (4)
C3A	0.0148 (17)	0.0251 (18)	0.0232 (19)	−0.0021 (13)	0.0026 (14)	0.0113 (15)

Geometric parameters (Å, º)

O1—C7	1.212 (3)	C6—H6	0.950
C1—C6	1.395 (4)	C7—H7	0.950
C1—C2	1.397 (4)	O1A—C7A	1.210 (6)
C1—C7	1.477 (4)	C7A—C1A	1.400 (6)
C2—C3	1.386 (4)	C7A—H7A	0.950
C2—Cl2	1.750 (3)	C1A—C3A^i	1.377 (4)
C3—C4	1.372 (4)	C1A—C2A	1.407 (4)
C3—H3	0.950	C1A—H4A	0.950
C4—C5	1.381 (4)	C2A—C3A	1.369 (4)
C4—H4	0.950	C2A—Cl2A	1.741 (3)
C5—C6	1.374 (4)	C3A—C1A^i	1.377 (4)
C5—Cl5	1.739 (3)	C3A—H3A	0.950
C6—C1—C2	117.6 (2)	O1—C7—C1	123.7 (3)
C6—C1—C7	118.9 (2)	O1—C7—H7	118.2
C2—C1—C7	123.5 (3)	C1—C7—H7	118.2
C3—C2—C1	121.8 (3)	O1A—C7A—C1A	125.5 (6)
C3—C2—Cl2	118.1 (2)	O1A—C7A—H7A	117.2
C1—C2—Cl2	120.1 (2)	C1A—C7A—H7A	117.2
C4—C3—C2	119.1 (2)	C3A^i—C1A—C7A	116.6 (4)
C4—C3—H3	120.5	C3A^i—C1A—C2A	118.8 (3)
C2—C3—H3	120.5	C7A—C1A—C2A	124.5 (4)
C3—C4—C5	120.2 (3)	C3A^i—C1A—H4A	120.7
C3—C4—H4	119.9	C2A—C1A—H4A	120.5
C5—C4—H4	119.9	C3A—C2A—C1A	120.7 (3)
C6—C5—C4	120.7 (3)	C3A—C2A—Cl2A	119.4 (2)
C6—C5—Cl5	118.8 (2)	C1A—C2A—Cl2A	119.9 (2)
C4—C5—Cl5	120.4 (2)	C2A—C3A—C1A^i	120.4 (3)
C5—C6—C1	120.6 (2)	C2A—C3A—H3A	119.8
C5—C6—H6	119.7	C1A^i—C3A—H3A	119.8
C1—C6—H6	119.7
C6—C1—C2—C3	2.0 (4)	C7—C1—C6—C5	178.2 (3)
C7—C1—C2—C3	−177.0 (3)	C6—C1—C7—O1	−8.8 (4)
C6—C1—C2—Cl2	−178.6 (2)	C2—C1—C7—O1	170.2 (3)
C7—C1—C2—Cl2	2.3 (4)	O1A—C7A—C1A—C3A^i	2.4 (7)
C1—C2—C3—C4	−2.0 (4)	O1A—C7A—C1A—C2A	−175.8 (5)
Cl2—C2—C3—C4	178.7 (2)	C3A^i—C1A—C2A—C3A	0.6 (5)
C2—C3—C4—C5	0.8 (4)	C7A—C1A—C2A—C3A	178.8 (3)
C3—C4—C5—C6	0.4 (4)	C3A^i—C1A—C2A—Cl2A	−179.6 (2)
C3—C4—C5—Cl5	−179.4 (2)	C7A—C1A—C2A—Cl2A	−1.4 (5)
C4—C5—C6—C1	−0.3 (4)	C1A—C2A—C3A—C1A^i	−0.6 (5)
Cl5—C5—C6—C1	179.5 (2)	Cl2A—C2A—C3A—C1A^i	179.6 (2)
C2—C1—C6—C5	−0.9 (4)

Symmetry code: (i) −x+1, −y+1, −z+1.

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Crystal data

C7H4Cl2O	F(000) = 176
Mr = 175.00	Dx = 1.653 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 5012 reflections
a = 3.8094 (3) Å	θ = 2.7–25.9°
b = 14.8887 (13) Å	µ = 0.84 mm^−1
c = 6.2014 (5) Å	T = 120 K
β = 91.849 (4)°	Plate, colourless
V = 351.54 (5) Å^3	0.30 × 0.20 × 0.10 mm
Z = 2

Data collection

Bruker-Nonius X8APEX-II CCD diffractometer	1272 independent reflections
Radiation source: fine-focus sealed tube	1220 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.026
thin–slice ω and ϕ scans	θmax = 26.0°, θmin = 3.6°
Absorption correction: multi-scan SADABS v.2.10 (Sheldrick, 2003) Ratio of minimum to maximum apparent transmission: 0.880814	h = −4→4
Tmin = 0.881, Tmax = 1.000	k = −17→18
6778 measured reflections	l = −7→7

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.024	H-atom parameters constrained
wR(F^2) = 0.055	w = 1/[σ^2(Fo^2) + (0.0295P)^2 + 0.0817P] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max < 0.001
1272 reflections	Δρmax = 0.24 e Å^−3
91 parameters	Δρmin = −0.22 e Å^−3
1 restraint	Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.03 (7)

Special details

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
Cl3	0.18489 (16)	0.20832 (3)	0.72154 (8)	0.02584 (16)
Cl4	0.49718 (15)	0.26293 (4)	0.27122 (8)	0.02766 (16)
O1	−0.1327 (4)	0.53317 (11)	1.0395 (2)	0.0293 (4)
C1	0.1395 (6)	0.47588 (16)	0.7287 (3)	0.0195 (5)
C2	0.1087 (6)	0.38585 (15)	0.7861 (4)	0.0194 (5)
H2	0.0118	0.3698	0.9200	0.023*
C3	0.2198 (6)	0.32030 (15)	0.6474 (4)	0.0202 (5)
C4	0.3601 (6)	0.34418 (15)	0.4501 (3)	0.0205 (5)
C5	0.3942 (6)	0.43341 (15)	0.3935 (3)	0.0223 (5)
H5	0.4926	0.4492	0.2599	0.027*
C6	0.2846 (6)	0.49944 (16)	0.5321 (3)	0.0216 (5)
H6	0.3076	0.5609	0.4941	0.026*
C7	0.0160 (6)	0.54677 (15)	0.8730 (4)	0.0252 (6)
H7	0.0556	0.6074	0.8328	0.030*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl3	0.0306 (3)	0.0227 (3)	0.0242 (3)	−0.0014 (3)	−0.0008 (2)	0.0003 (2)
Cl4	0.0273 (3)	0.0356 (3)	0.0201 (3)	0.0036 (3)	0.0001 (2)	−0.0056 (2)
O1	0.0340 (11)	0.0306 (8)	0.0235 (9)	−0.0037 (8)	0.0059 (7)	−0.0026 (7)
C1	0.0116 (11)	0.0253 (12)	0.0214 (12)	−0.0019 (10)	−0.0059 (9)	0.0006 (9)
C2	0.0121 (12)	0.0281 (12)	0.0178 (10)	−0.0018 (10)	−0.0029 (8)	0.0013 (9)
C3	0.0160 (12)	0.0236 (12)	0.0206 (10)	0.0000 (10)	−0.0061 (9)	0.0024 (9)
C4	0.0120 (12)	0.0298 (11)	0.0192 (10)	0.0014 (10)	−0.0046 (8)	−0.0032 (10)
C5	0.0164 (13)	0.0350 (14)	0.0156 (10)	−0.0017 (11)	−0.0012 (8)	0.0052 (10)
C6	0.0177 (13)	0.0234 (11)	0.0235 (11)	−0.0009 (10)	−0.0029 (9)	0.0042 (9)
C7	0.0211 (14)	0.0244 (13)	0.0297 (13)	−0.0021 (10)	−0.0046 (11)	0.0008 (10)

Geometric parameters (Å, º)

Cl3—C3	1.736 (2)	C2—H2	0.950
Cl4—C4	1.733 (2)	C3—C4	1.397 (3)
O1—C7	1.210 (3)	C4—C5	1.381 (3)
C1—C2	1.393 (3)	C5—C6	1.379 (3)
C1—C6	1.400 (3)	C5—H5	0.950
C1—C7	1.471 (3)	C6—H6	0.950
C2—C3	1.376 (3)	C7—H7	0.950
C2—C1—C6	120.2 (2)	C3—C4—Cl4	120.98 (18)
C2—C1—C7	120.2 (2)	C6—C5—C4	119.65 (19)
C6—C1—C7	119.6 (2)	C6—C5—H5	120.2
C3—C2—C1	119.5 (2)	C4—C5—H5	120.2
C3—C2—H2	120.3	C5—C6—C1	120.0 (2)
C1—C2—H2	120.3	C5—C6—H6	120.0
C2—C3—C4	120.1 (2)	C1—C6—H6	120.0
C2—C3—Cl3	119.19 (18)	O1—C7—C1	124.5 (2)
C4—C3—Cl3	120.74 (17)	O1—C7—H7	117.7
C5—C4—C3	120.6 (2)	C1—C7—H7	117.7
C5—C4—Cl4	118.43 (16)
C6—C1—C2—C3	−0.5 (3)	C3—C4—C5—C6	−0.8 (3)
C7—C1—C2—C3	178.8 (2)	Cl4—C4—C5—C6	179.47 (17)
C1—C2—C3—C4	−0.4 (3)	C4—C5—C6—C1	−0.1 (3)
C1—C2—C3—Cl3	179.31 (17)	C2—C1—C6—C5	0.7 (3)
C2—C3—C4—C5	1.0 (3)	C7—C1—C6—C5	−178.6 (2)
Cl3—C3—C4—C5	−178.67 (18)	C2—C1—C7—O1	−4.1 (3)
C2—C3—C4—Cl4	−179.25 (18)	C6—C1—C7—O1	175.2 (2)
Cl3—C3—C4—Cl4	1.1 (3)

(6)

Crystal data

C7H4Cl2O	F(000) = 704
Mr = 175.00	Dx = 1.628 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 1496 reflections
a = 3.7785 (5) Å	θ = 3.4–20.8°
b = 31.353 (5) Å	µ = 0.82 mm^−1
c = 12.058 (2) Å	T = 120 K
β = 91.546 (6)°	Plate, colourless
V = 1428.0 (4) Å^3	0.30 × 0.15 × 0.01 mm
Z = 8

Data collection

Bruker-Nonius X8APEX-II CCD diffractometer	2678 independent reflections
Radiation source: fine-focus sealed tube	1731 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.069
thin–slice ω and ϕ scans	θmax = 25.7°, θmin = 3.6°
Absorption correction: multi-scan Ratio of minimum to maximum apparent transmission: 0.703457 SADABS v.2.10 (Sheldrick, 2003)	h = −4→4
Tmin = 0.698, Tmax = 0.992	k = −37→38
13283 measured reflections	l = −14→14

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)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.098	H-atom parameters constrained
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0444P)^2] where P = (Fo^2 + 2Fc^2)/3
2678 reflections	(Δ/σ)max = 0.001
181 parameters	Δρmax = 0.38 e Å^−3
0 restraints	Δρmin = −0.35 e Å^−3

Special details

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
O1	0.1658 (7)	0.19259 (7)	0.1451 (2)	0.0285 (6)
C1	0.4429 (8)	0.17430 (10)	0.3185 (3)	0.0160 (8)
C2	0.3804 (9)	0.13052 (10)	0.3110 (3)	0.0190 (8)
H2	0.2700	0.1185	0.2465	0.023*
C3	0.4828 (9)	0.10497 (10)	0.3997 (3)	0.0181 (8)
Cl3	0.3992 (3)	0.05057 (3)	0.39358 (7)	0.0281 (3)
C4	0.6462 (8)	0.12155 (10)	0.4943 (3)	0.0179 (8)
H4	0.7157	0.1035	0.5544	0.022*
C5	0.7057 (9)	0.16505 (11)	0.4991 (3)	0.0170 (8)
Cl5	0.9051 (2)	0.18681 (3)	0.61796 (7)	0.0230 (2)
C6	0.6065 (9)	0.19175 (11)	0.4130 (3)	0.0184 (8)
H6	0.6489	0.2216	0.4179	0.022*
C7	0.3317 (9)	0.20325 (11)	0.2279 (3)	0.0235 (9)
H7	0.3948	0.2325	0.2349	0.028*
O1A	0.3662 (7)	0.21095 (7)	0.8475 (2)	0.0309 (7)
C1A	0.5570 (9)	0.14281 (10)	0.9123 (3)	0.0170 (8)
C2A	0.4249 (8)	0.12059 (10)	0.8201 (3)	0.0185 (8)
H2A	0.3249	0.1354	0.7580	0.022*
C3A	0.4429 (8)	0.07671 (10)	0.8211 (3)	0.0171 (8)
Cl3A	0.2794 (2)	0.04810 (3)	0.70719 (7)	0.0238 (2)
C4A	0.5869 (8)	0.05441 (10)	0.9112 (3)	0.0171 (8)
H4A	0.5977	0.0241	0.9107	0.021*
C5A	0.7141 (9)	0.07749 (11)	1.0017 (3)	0.0172 (8)
Cl5A	0.8886 (2)	0.05036 (3)	1.11618 (7)	0.0224 (2)
C6A	0.7031 (8)	0.12161 (10)	1.0033 (3)	0.0178 (8)
H6A	0.7940	0.1370	1.0656	0.021*
C7A	0.5342 (9)	0.19001 (11)	0.9146 (3)	0.0223 (9)
H7A	0.6592	0.2047	0.9724	0.027*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0291 (17)	0.0353 (15)	0.0207 (15)	−0.0026 (12)	−0.0085 (12)	−0.0005 (12)
C1	0.013 (2)	0.0199 (19)	0.0152 (19)	−0.0012 (14)	0.0012 (15)	−0.0001 (15)
C2	0.014 (2)	0.025 (2)	0.018 (2)	−0.0004 (15)	0.0010 (15)	−0.0042 (15)
C3	0.011 (2)	0.0193 (19)	0.024 (2)	−0.0001 (14)	0.0022 (16)	−0.0032 (15)
Cl3	0.0340 (6)	0.0177 (5)	0.0325 (6)	−0.0040 (4)	−0.0009 (4)	−0.0010 (4)
C4	0.013 (2)	0.024 (2)	0.0167 (19)	0.0012 (15)	0.0011 (15)	0.0043 (15)
C5	0.012 (2)	0.025 (2)	0.0140 (19)	−0.0005 (15)	−0.0023 (15)	0.0003 (15)
Cl5	0.0220 (6)	0.0283 (5)	0.0186 (5)	0.0002 (4)	−0.0046 (4)	−0.0047 (4)
C6	0.016 (2)	0.0185 (19)	0.0210 (19)	−0.0010 (15)	0.0032 (15)	−0.0026 (15)
C7	0.025 (3)	0.023 (2)	0.022 (2)	−0.0008 (17)	−0.0007 (18)	0.0044 (17)
O1A	0.0423 (18)	0.0225 (14)	0.0274 (15)	0.0110 (13)	−0.0069 (13)	0.0009 (12)
C1A	0.013 (2)	0.0184 (19)	0.0195 (19)	0.0031 (15)	0.0018 (15)	0.0005 (15)
C2A	0.014 (2)	0.028 (2)	0.0144 (19)	0.0004 (15)	−0.0025 (15)	0.0010 (15)
C3A	0.016 (2)	0.020 (2)	0.0158 (19)	−0.0006 (15)	0.0045 (15)	−0.0014 (15)
Cl3A	0.0242 (6)	0.0279 (5)	0.0190 (5)	−0.0017 (4)	−0.0040 (4)	−0.0036 (4)
C4A	0.013 (2)	0.0179 (19)	0.0204 (19)	−0.0016 (15)	0.0040 (15)	0.0039 (16)
C5A	0.009 (2)	0.023 (2)	0.019 (2)	−0.0003 (15)	−0.0014 (15)	0.0031 (16)
Cl5A	0.0224 (6)	0.0247 (5)	0.0197 (5)	0.0005 (4)	−0.0047 (4)	0.0052 (4)
C6A	0.012 (2)	0.025 (2)	0.0164 (19)	−0.0038 (15)	0.0025 (15)	0.0003 (16)
C7A	0.025 (2)	0.023 (2)	0.020 (2)	−0.0008 (17)	0.0036 (17)	0.0007 (17)

Geometric parameters (Å, º)

O1—C7	1.211 (4)	O1A—C7A	1.209 (4)
C1—C6	1.393 (4)	C1A—C6A	1.385 (4)
C1—C2	1.395 (4)	C1A—C2A	1.394 (4)
C1—C7	1.473 (4)	C1A—C7A	1.483 (4)
C2—C3	1.383 (4)	C2A—C3A	1.378 (4)
C2—H2	0.950	C2A—H2A	0.950
C3—C4	1.384 (4)	C3A—C4A	1.391 (4)
C3—Cl3	1.736 (3)	C3A—Cl3A	1.739 (3)
C4—C5	1.383 (4)	C4A—C5A	1.385 (4)
C4—H4	0.950	C4A—H4A	0.950
C5—C6	1.378 (4)	C5A—C6A	1.384 (4)
C5—Cl5	1.741 (3)	C5A—Cl5A	1.736 (3)
C6—H6	0.950	C6A—H6A	0.950
C7—H7	0.950	C7A—H7A	0.950
C6—C1—C2	120.7 (3)	C6A—C1A—C2A	121.3 (3)
C6—C1—C7	118.4 (3)	C6A—C1A—C7A	119.1 (3)
C2—C1—C7	120.9 (3)	C2A—C1A—C7A	119.6 (3)
C3—C2—C1	118.4 (3)	C3A—C2A—C1A	118.4 (3)
C3—C2—H2	120.8	C3A—C2A—H2A	120.8
C1—C2—H2	120.8	C1A—C2A—H2A	120.8
C2—C3—C4	122.0 (3)	C2A—C3A—C4A	121.8 (3)
C2—C3—Cl3	119.3 (3)	C2A—C3A—Cl3A	119.5 (3)
C4—C3—Cl3	118.7 (3)	C4A—C3A—Cl3A	118.7 (3)
C5—C4—C3	118.2 (3)	C5A—C4A—C3A	118.3 (3)
C5—C4—H4	120.9	C5A—C4A—H4A	120.9
C3—C4—H4	120.9	C3A—C4A—H4A	120.9
C6—C5—C4	121.8 (3)	C6A—C5A—C4A	121.6 (3)
C6—C5—Cl5	119.0 (3)	C6A—C5A—Cl5A	119.3 (3)
C4—C5—Cl5	119.2 (3)	C4A—C5A—Cl5A	119.1 (3)
C5—C6—C1	118.9 (3)	C5A—C6A—C1A	118.7 (3)
C5—C6—H6	120.6	C5A—C6A—H6A	120.6
C1—C6—H6	120.6	C1A—C6A—H6A	120.6
O1—C7—C1	124.9 (3)	O1A—C7A—C1A	124.0 (3)
O1—C7—H7	117.6	O1A—C7A—H7A	118.0
C1—C7—H7	117.6	C1A—C7A—H7A	118.0
C6—C1—C2—C3	0.3 (5)	C6A—C1A—C2A—C3A	−0.1 (5)
C7—C1—C2—C3	−178.5 (3)	C7A—C1A—C2A—C3A	−178.7 (3)
C1—C2—C3—C4	−0.4 (5)	C1A—C2A—C3A—C4A	0.2 (5)
C1—C2—C3—Cl3	178.6 (2)	C1A—C2A—C3A—Cl3A	179.9 (2)
C2—C3—C4—C5	0.2 (5)	C2A—C3A—C4A—C5A	0.1 (5)
Cl3—C3—C4—C5	−178.8 (2)	Cl3A—C3A—C4A—C5A	−179.6 (3)
C3—C4—C5—C6	0.1 (5)	C3A—C4A—C5A—C6A	−0.6 (5)
C3—C4—C5—Cl5	179.1 (2)	C3A—C4A—C5A—Cl5A	179.0 (2)
C4—C5—C6—C1	−0.2 (5)	C4A—C5A—C6A—C1A	0.8 (5)
Cl5—C5—C6—C1	−179.2 (3)	Cl5A—C5A—C6A—C1A	−178.8 (2)
C2—C1—C6—C5	0.0 (5)	C2A—C1A—C6A—C5A	−0.4 (5)
C7—C1—C6—C5	178.8 (3)	C7A—C1A—C6A—C5A	178.2 (3)
C6—C1—C7—O1	−174.6 (3)	C6A—C1A—C7A—O1A	−168.6 (3)
C2—C1—C7—O1	4.2 (6)	C2A—C1A—C7A—O1A	10.0 (5)