3,4,6-Trichloro-5-cyano-2-hydroxy­benzamide

The title compound, C₈H₃Cl₃N₂O₂, forms crystals in which hydrogen-bonding and Cl...N inter­actions appear to be equally important to the structure. The mol­ecules form ribbons held together alternately by cyclic (CONH)₂ and cyclic (ClCCC[triple bond]N)₂ inter­actions. The ribbons assemble into layers through Cl...Cl inter­actions. The layers are held together by NH...N[triple bond]C hydrogen bonds, as well as by π–π inter­actions.

S1. Comment

In 3,5-dichloro-4-cyanobenzoic acid (Britton, 2006), the molecules are involved in cyclic (COOH)₂ interactions, graph set R₂²(8) (Etter, 1990), as well as in cyclic (ClCCC≡N)₂ interactions. Bernstein et al. (1995) have suggested that graph-set analysis might be extended to other systems than hydrogen bonding. In this spirit, cyclic Cl···N interactions can be described by the graph set R₂²(10), with the electron acceptor Cl replacing H. The title compound, (I), was studied in search of another example of the same phenomenon.

Fig. 1 shows the atom labelling and the anisotropic displacement ellipsoids of (I). The bond lengths and angles are normal. The plane of the benzamide group, excluding the H atoms, is rotated 31.2 (10)° out of the plane of the C₆ ring, while the plane of the NH₂ group is rotated another 10 (2)° out of the plane of the benzamide group. The hydroxy group is intramolecularly hydrogen bonded to atom O1, graph set S(6); geometric details are given in Table 1.

One layer of the packing in (I) is shown in Fig. 2. The molecules form ribbons along the [211] direction, held together by the anticipated (CONH)₂ cyclic hydrogen bonds and Cl···N interactions. Geometric data for the hydrogen bond are given in Table 1. Data for the Cl···N interaction are: C4—Cl4···N2ⁱ 171.66 (5)°, Cl4···N2ⁱ 3.0809 (13) Å and Cl4···N2ⁱ≡C8ⁱ 129.09 (11)° [symmetry code: (i) 2 - x, 2 - y, 1 - z]. The ribbons assemble into layers parallel to the (102) plane, held together by Cl···Cl interactions: C3—Cl3···Cl6ⁱⁱ 138.11 (5)°, Cl3···Cl6ⁱⁱ 3.3900 (5) Å and Cl3···Cl6ⁱⁱ—C6ⁱⁱ 136.03 (4)° [symmetry code: (ii) x, 1 + y, z].

The layers are held together by N—H···N≡C hydrogen bonds. Fig. 3 shows the hydrogen bonds between two molecules in adjacent layers; geometric details are given in Table 1. Pairs of molecules form cyclic dimers, graph set R₂²(16). In a single layer, alternate molecules form such dimers with adjacent layers on opposite sides of the original sheet.

It would be of interest to determine the structure of the corresponding carboxylic acid. It seems reasonable to suppose that similar layers of molecules might form, but that the stacking of the layers would be different in the absence of interlayer hydrogen bonds.

Related literature

For related literature, see: Bernstein et al. (1995); Britton (2006); Etter (1990).

S2. Experimental

The compound was obtained from the Diamond Shamrock Corporation. The crystal used was from the original sample.

S3. Refinement

The solution and refinement were straightforward. The H-atom positions and isotropic displacement parameters were refined.

Computing details

Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of the title compound, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. One layer of the crystal packing of (I). Hydrogen bonds and Cl···N≡ C interactions are shown as dashed lines. The Cl···Cl interactions are shown as dotted lines.
	Fig. 3. Adjacent molecules of (I) from two different layers. Hydrogen bonds are shown as dashed lines.

3,4,6-Trichloro-5-cyano-2-hydroxybenzamide

Crystal data

C8H3Cl3N2O2	Z = 2
Mr = 265.47	F(000) = 264
Triclinic, P1	Dx = 1.830 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.3020 (6) Å	Cell parameters from 2326 reflections
b = 9.0437 (8) Å	θ = 2.3–27.4°
c = 9.3822 (9) Å	µ = 0.93 mm^−1
α = 109.196 (1)°	T = 174 K
β = 94.937 (1)°	Prism, colourless
γ = 104.076 (1)°	0.45 × 0.30 × 0.25 mm
V = 481.72 (8) Å^3

Data collection

Bruker SMART 1K CCD area-detector diffractometer	2164 independent reflections
Radiation source: fine-focus sealed tube	2036 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.017
ω scans	θmax = 27.5°, θmin = 2.3°
Absorption correction: multi-scan [SADABS (Sheldrick, 2003; Blessing, 1995)]	h = −8→8
Tmin = 0.74, Tmax = 0.79	k = −11→11
5659 measured reflections	l = −12→12

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.022	All H-atom parameters refined
wR(F^2) = 0.063	w = 1/[σ^2(Fo^2) + (0.031P)^2 + 0.208P], where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max = 0.001
2164 reflections	Δρmax = 0.43 e Å^−3
149 parameters	Δρmin = −0.22 e Å^−3
0 restraints	Extinction correction: SHELXTL (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.023 (2)

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

	x	y	z	Uiso*/Ueq
Cl3	0.37098 (6)	1.18489 (4)	0.80299 (4)	0.02742 (11)
Cl4	0.75184 (5)	1.08721 (4)	0.62495 (4)	0.02395 (10)
Cl6	0.58111 (6)	0.52885 (4)	0.72883 (4)	0.02654 (11)
O1	0.10836 (16)	0.70392 (12)	1.00184 (11)	0.0247 (2)
O2	0.15037 (17)	0.94932 (12)	0.91936 (11)	0.0235 (2)
H2	0.109 (3)	0.883 (2)	0.962 (2)	0.040 (5)*
N1	0.1264 (2)	0.47587 (14)	0.81978 (14)	0.0248 (3)
H11	0.037 (3)	0.416 (2)	0.861 (2)	0.032 (4)*
H12	0.156 (3)	0.432 (2)	0.735 (2)	0.033 (5)*
N2	0.9345 (2)	0.72514 (16)	0.53256 (14)	0.0294 (3)
C1	0.3346 (2)	0.74280 (15)	0.82112 (13)	0.0166 (2)
C2	0.3022 (2)	0.89712 (15)	0.84156 (14)	0.0176 (2)
C3	0.4274 (2)	1.00282 (15)	0.77880 (14)	0.0186 (2)
C4	0.5929 (2)	0.95968 (15)	0.70084 (14)	0.0182 (2)
C5	0.6338 (2)	0.80989 (15)	0.68383 (14)	0.0182 (3)
C6	0.5062 (2)	0.70427 (15)	0.74507 (14)	0.0175 (2)
C7	0.1831 (2)	0.63648 (16)	0.88678 (14)	0.0183 (2)
C8	0.8037 (2)	0.76415 (16)	0.60143 (15)	0.0213 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl3	0.03132 (19)	0.02051 (17)	0.0373 (2)	0.01134 (13)	0.00961 (14)	0.01559 (14)
Cl4	0.02459 (17)	0.02381 (17)	0.02327 (17)	−0.00040 (13)	0.00747 (12)	0.01283 (13)
Cl6	0.02574 (18)	0.02134 (17)	0.0402 (2)	0.01189 (13)	0.01471 (14)	0.01511 (14)
O1	0.0302 (5)	0.0209 (5)	0.0235 (5)	0.0048 (4)	0.0154 (4)	0.0082 (4)
O2	0.0253 (5)	0.0230 (5)	0.0290 (5)	0.0119 (4)	0.0160 (4)	0.0119 (4)
N1	0.0310 (6)	0.0178 (5)	0.0258 (6)	0.0035 (5)	0.0160 (5)	0.0082 (5)
N2	0.0275 (6)	0.0319 (7)	0.0285 (6)	0.0076 (5)	0.0134 (5)	0.0090 (5)
C1	0.0169 (6)	0.0176 (6)	0.0161 (5)	0.0039 (5)	0.0057 (4)	0.0074 (5)
C2	0.0169 (6)	0.0191 (6)	0.0170 (6)	0.0053 (5)	0.0051 (5)	0.0063 (5)
C3	0.0204 (6)	0.0170 (6)	0.0204 (6)	0.0056 (5)	0.0044 (5)	0.0087 (5)
C4	0.0182 (6)	0.0192 (6)	0.0165 (5)	0.0010 (5)	0.0040 (5)	0.0085 (5)
C5	0.0166 (6)	0.0206 (6)	0.0168 (6)	0.0037 (5)	0.0062 (5)	0.0064 (5)
C6	0.0181 (6)	0.0163 (6)	0.0184 (6)	0.0054 (5)	0.0047 (5)	0.0061 (5)
C7	0.0178 (6)	0.0198 (6)	0.0187 (6)	0.0035 (5)	0.0061 (5)	0.0095 (5)
C8	0.0203 (6)	0.0219 (6)	0.0195 (6)	0.0025 (5)	0.0059 (5)	0.0068 (5)

Geometric parameters (Å, º)

Cl3—C3	1.7153 (13)	N2—C8	1.1424 (17)
Cl4—C4	1.7151 (12)	C1—C6	1.3975 (17)
Cl6—C6	1.7263 (13)	C1—C2	1.4127 (17)
O1—C7	1.2464 (15)	C1—C7	1.5033 (16)
O2—C2	1.3360 (15)	C2—C3	1.4023 (18)
O2—H2	0.83 (2)	C3—C4	1.3841 (18)
N1—C7	1.3194 (17)	C4—C5	1.4006 (18)
N1—H11	0.891 (19)	C5—C6	1.3983 (17)
N1—H12	0.823 (19)	C5—C8	1.4362 (17)
C2—O2—H2	104.4 (13)	C3—C4—C5	119.89 (11)
C7—N1—H11	118.0 (11)	C3—C4—Cl4	121.23 (10)
C7—N1—H12	121.6 (13)	C5—C4—Cl4	118.87 (10)
H11—N1—H12	119.7 (17)	C6—C5—C4	119.76 (11)
C6—C1—C2	117.43 (11)	C6—C5—C8	120.28 (12)
C6—C1—C7	126.05 (11)	C4—C5—C8	119.94 (11)
C2—C1—C7	116.51 (11)	C1—C6—C5	121.61 (11)
O2—C2—C3	116.57 (11)	C1—C6—Cl6	122.11 (10)
O2—C2—C1	122.22 (11)	C5—C6—Cl6	116.21 (9)
C3—C2—C1	121.20 (11)	O1—C7—N1	121.54 (12)
C4—C3—C2	119.98 (12)	O1—C7—C1	118.40 (11)
C4—C3—Cl3	121.72 (10)	N1—C7—C1	120.02 (11)
C2—C3—Cl3	118.30 (10)	N2—C8—C5	178.17 (15)
C6—C1—C2—O2	−176.57 (12)	C3—C4—C5—C8	179.27 (12)
C7—C1—C2—O2	2.15 (18)	Cl4—C4—C5—C8	−1.16 (17)
C6—C1—C2—C3	4.26 (18)	C2—C1—C6—C5	−3.44 (18)
C7—C1—C2—C3	−177.02 (11)	C7—C1—C6—C5	177.98 (12)
O2—C2—C3—C4	177.93 (12)	C2—C1—C6—Cl6	173.60 (9)
C1—C2—C3—C4	−2.85 (19)	C7—C1—C6—Cl6	−4.99 (18)
O2—C2—C3—Cl3	−1.53 (16)	C4—C5—C6—C1	1.21 (19)
C1—C2—C3—Cl3	177.69 (10)	C8—C5—C6—C1	−177.72 (12)
C2—C3—C4—C5	0.48 (19)	C4—C5—C6—Cl6	−175.99 (10)
Cl3—C3—C4—C5	179.92 (10)	C8—C5—C6—Cl6	5.08 (16)
C2—C3—C4—Cl4	−179.07 (9)	C6—C1—C7—O1	149.53 (13)
Cl3—C3—C4—Cl4	0.37 (16)	C2—C1—C7—O1	−29.06 (17)
C3—C4—C5—C6	0.34 (19)	C6—C1—C7—N1	−32.67 (19)
Cl4—C4—C5—C6	179.90 (10)	C2—C1—C7—N1	148.73 (13)