3,5-Dichloro­salicylaldehyde

Abstract

The title compound (systematic name: 3,5-dichloro-2-hydroxy­benzaldehyde), C₇H₄Cl₂O₂, crystallizes as discrete mol­ecules, the conformation of which may be influenced by an intra­molecular hydr­oxy–carbonyl O—H⋯O hydrogen bond.

Related literature

For the crystal structure of 3′,5′-dichloro­acetophenone, see: Filarowski et al. (2004 ▶).

Experimental

Crystal data

• C₇H₄Cl₂O₂

• M _r = 191.00

• Monoclinic,

• a = 8.2823 (2) Å

• b = 13.7412 (3) Å

• c = 7.0973 (2) Å

• β = 115.185 (2)°

• V = 730.95 (3) ų

• Z = 4

• Mo Kα radiation

• μ = 0.82 mm⁻¹

• T = 100 (2) K

• 0.25 × 0.15 × 0.05 mm

Data collection

• Bruker SMART APEX diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.701, T _max = 0.960

• 8436 measured reflections

• 1672 independent reflections

• 1303 reflections with I > 2σ(I)

• R _int = 0.058

Refinement

• R[F ² > 2σ(F ²)] = 0.037

• wR(F ²) = 0.101

• S = 1.05

• 1672 reflections

• 104 parameters

• 1 restraint

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.59 e Å⁻³

• Δρ_min = −0.49 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: X-SEED (Barbour, 2001 ▶); software used to prepare material for publication: publCIF (Westrip, 2008 ▶).

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O2	0.84 (1)	1.87 (2)	2.628 (3)	149 (3)

supplementary crystallographic information

Comment

The intramolecular hydrogen bonds in small molecules such as ortho-hydroxyacetopheonone and its derivatives has been extensively studied, both theoretically and crystallographically. Such compounds can exist in a keto-enol equilibrium. For 3',5'-dichloroacetophenone, geometry-optimization calculations suggest that the presence of two chlorine substituents raises the acidity of the hydroxyl proton and decreases the basicity of the carbonyl function. The O···O distance in the hydrogen bond is 2.567 (3) Å (Filarowski et al., 2004).

The hydrogen bond in the title molecule (I) is longer with an O···O distance of 2.628 (3) Å. 3,5-Dichlorosalicylaldehyde (I) exists as a monomeric compound (Fig. 1); the molecule is flat and all bond dimensions are normal.

Experimental

The compound was purchased from Aldrich Chemical Company; the chemical exists as colorless prismatic crystals. The bulk chemical has a yellow color.

Refinement

Carbon-bound H-atoms were placed in calculated positions (C—H 0.95 Å) and were included in the refinement in the riding model approximation, with U(H) set to 1.2U(C). The oxygen-bound H atom was located in a difference Fourier map, and was refined with a distance restraint of O–H 0.84±0.01 Å; its temperature factor was freely refined.

Figures

Fig. 1.

70% Probability thermal ellipsoid plot of 3,5-dichlorosalicylaldehyde. Hydrogen atoms are drawn as spheres of arbitrary radius.

Crystal data

C7H4Cl2O2	F(000) = 384
Mr = 191.00	Dx = 1.736 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3128 reflections
a = 8.2823 (2) Å	θ = 3.0–28.2°
b = 13.7412 (3) Å	µ = 0.82 mm−1
c = 7.0973 (2) Å	T = 100 K
β = 115.185 (2)°	Block, colorless
V = 730.95 (3) Å3	0.25 × 0.15 × 0.05 mm
Z = 4

Data collection

Bruker SMART APEXII diffractometer	1672 independent reflections
Radiation source: fine-focus sealed tube	1303 reflections with I > 2σ(I)
graphite	Rint = 0.058
ω scans	θmax = 27.5°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −10→10
Tmin = 0.701, Tmax = 0.960	k = −17→17
8436 measured reflections	l = −9→9

Refinement

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)] = 0.037	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.101	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ2(Fo2) + (0.0416P)2 + 0.8939P] where P = (Fo2 + 2Fc2)/3
1672 reflections	(Δ/σ)max = 0.001
104 parameters	Δρmax = 0.59 e Å−3
1 restraint	Δρmin = −0.49 e Å−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cl1	0.17794 (9)	0.14230 (4)	0.48280 (10)	0.01972 (18)
Cl2	0.15345 (9)	0.53148 (4)	0.39904 (11)	0.02166 (19)
O1	0.5328 (3)	0.17615 (13)	0.8080 (3)	0.0200 (4)
H1	0.631 (3)	0.192 (3)	0.905 (4)	0.038 (10)*
O2	0.7916 (3)	0.28892 (14)	1.0580 (3)	0.0252 (4)
C1	0.4488 (3)	0.25960 (17)	0.7232 (4)	0.0155 (5)
C2	0.2766 (3)	0.25497 (17)	0.5629 (4)	0.0164 (5)
C3	0.1851 (4)	0.33804 (17)	0.4659 (4)	0.0168 (5)
H3	0.0680	0.3339	0.3572	0.020*
C4	0.2680 (4)	0.42815 (17)	0.5306 (4)	0.0177 (5)
C5	0.4355 (4)	0.43592 (17)	0.6906 (4)	0.0179 (5)
H5	0.4890	0.4980	0.7336	0.021*
C6	0.5266 (3)	0.35155 (17)	0.7897 (4)	0.0160 (5)
C7	0.7028 (4)	0.35892 (18)	0.9634 (4)	0.0206 (6)
H7	0.7517	0.4220	1.0058	0.025*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Cl1	0.0225 (3)	0.0110 (3)	0.0228 (3)	−0.0036 (2)	0.0068 (3)	−0.0026 (2)
Cl2	0.0204 (3)	0.0122 (3)	0.0276 (4)	0.0029 (2)	0.0056 (3)	0.0051 (2)
O1	0.0193 (10)	0.0111 (8)	0.0243 (11)	0.0025 (7)	0.0042 (9)	0.0025 (7)
O2	0.0211 (10)	0.0197 (9)	0.0272 (11)	0.0004 (8)	0.0030 (9)	0.0033 (8)
C1	0.0182 (13)	0.0111 (10)	0.0180 (12)	0.0028 (9)	0.0083 (11)	0.0016 (9)
C2	0.0216 (13)	0.0106 (10)	0.0186 (12)	−0.0017 (9)	0.0100 (11)	−0.0016 (9)
C3	0.0163 (13)	0.0162 (12)	0.0172 (13)	−0.0004 (9)	0.0063 (11)	−0.0007 (9)
C4	0.0201 (14)	0.0114 (11)	0.0213 (13)	0.0038 (9)	0.0086 (12)	0.0032 (9)
C5	0.0202 (14)	0.0108 (11)	0.0228 (14)	−0.0024 (9)	0.0093 (12)	0.0000 (9)
C6	0.0151 (13)	0.0123 (11)	0.0195 (13)	−0.0004 (9)	0.0064 (11)	0.0003 (9)
C7	0.0212 (14)	0.0149 (12)	0.0229 (14)	−0.0029 (10)	0.0068 (12)	−0.0003 (10)

Geometric parameters (Å, °)

Cl1—C2	1.730 (2)	C3—C4	1.395 (3)
Cl2—C4	1.742 (2)	C3—H3	0.9500
O1—C1	1.343 (3)	C4—C5	1.373 (4)
O1—H1	0.840 (10)	C5—C6	1.399 (3)
O2—C7	1.223 (3)	C5—H5	0.9500
C1—C2	1.397 (4)	C6—C7	1.459 (4)
C1—C6	1.406 (3)	C7—H7	0.9500
C2—C3	1.381 (3)
C1—O1—H1	107 (3)	C5—C4—Cl2	120.53 (19)
O1—C1—C2	118.7 (2)	C3—C4—Cl2	117.9 (2)
O1—C1—C6	122.7 (2)	C4—C5—C6	119.4 (2)
C2—C1—C6	118.5 (2)	C4—C5—H5	120.3
C3—C2—C1	121.5 (2)	C6—C5—H5	120.3
C3—C2—Cl1	119.6 (2)	C5—C6—C1	120.3 (2)
C1—C2—Cl1	118.96 (18)	C5—C6—C7	119.9 (2)
C2—C3—C4	118.7 (2)	C1—C6—C7	119.8 (2)
C2—C3—H3	120.6	O2—C7—C6	124.1 (2)
C4—C3—H3	120.6	O2—C7—H7	118.0
C5—C4—C3	121.6 (2)	C6—C7—H7	118.0
O1—C1—C2—C3	−178.3 (2)	Cl2—C4—C5—C6	−178.17 (19)
C6—C1—C2—C3	2.0 (4)	C4—C5—C6—C1	1.3 (4)
O1—C1—C2—Cl1	0.8 (3)	C4—C5—C6—C7	−178.4 (2)
C6—C1—C2—Cl1	−178.90 (18)	O1—C1—C6—C5	177.7 (2)
C1—C2—C3—C4	0.1 (4)	C2—C1—C6—C5	−2.7 (4)
Cl1—C2—C3—C4	−179.03 (19)	O1—C1—C6—C7	−2.6 (4)
C2—C3—C4—C5	−1.5 (4)	C2—C1—C6—C7	177.1 (2)
C2—C3—C4—Cl2	177.52 (18)	C5—C6—C7—O2	−179.8 (3)
C3—C4—C5—C6	0.9 (4)	C1—C6—C7—O2	0.5 (4)

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O2	0.84 (1)	1.87 (2)	2.628 (3)	149 (3)