5-Chloro-2-methyl­isothia­zolin-3-one: inter­molecular two-dimensional networks via unusual C—Cl...O=C inter­actions

The title mol­ecule, C₄H₄ClNOS, contains an essentially planar five-membered ring. The C [pdbond]C(=O) bond is slightly longer than expected. In the crystal structure, two-dimensional networks are formed through inter­molecular C—Cl...O=C inter­actions [Cl...O = 2.9811 (19) Å].

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.044
• wR factor = 0.098
• Data-to-parameter ratio = 19.9

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT322_ALERT_2_C Check Hybridisation of  S1     in Main Residue .          ?
PLAT431_ALERT_2_C Short Inter HL..A Contact  Cl1    ..  O1      ..       2.98 Ang.

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The title compound, 5-Chloro-2-methylisothiazolin-3-one (I) is widely used as a biocide. Some molecular structures which contain (I) as co-crystals have been reported previously (Suzuki et al., 1997; Sekine, Jomoto et al., 2003; Sekine, Mitsumori et al., 2003) but there are no reports on the crystal structure of (I) itself. We are interested in the relationship between the crystal structures of isothiazolines and their biocidal activities (Kato et al., 2007) and report here the crystal structure of (I).

The molecular structure of (I), with the atom-labelling scheme, is shown in Fig. 1. Selected bond lengths and angles are shown in Table 1. The C1—C2 bond length is slightly longer than that previously reported (1.441 (3) Å, Sekine, Mitsumori et al., 2003; 1.438 (4) Å, Sekine, Jomoto et al., 2003; 1.437 Å, Suzuki et al., 1997). The five-membered ring (S1/N1/C1—C3) is planar and the largest deviation from the plane being for atom N1 [0.0086 (12) Å]. The deviation of the C4 atom in the methyl group from the five-membered ring is 0.2214 (36) Å despite the N1 atom with sp³-hybridization state. The planarity around the N1 atom indicates the delocalization of the lone pair of electrons on the N1 atom. An intermolecular interaction between Cl1 and O1 is observed (Fig. 2) and its distance is 2.9811 (19) Å. This distance is the same as reported previously (2.981 (2) Å, Fujii et al., 2005). The Cl1 atom accepts the lone pair electrons of O1 and this intermolecular interaction stabilizes the crystal structure.

We performed the DFT calculations on (I) and 2-methylisothiazolin-3-one (II) by the B3LYP method for elucidating its electronic structure using the Gaussian03 package program (Frisch et al., 2003). The 6–31+G(d,p) basis set was used for all the elements. The optimized geometry shows a good agreement with the crystal structure. The Wiberg bond indices (Wiberg, 1968) were evaluated by natural-bond orbital (NBO) analysis (Glendening et al., 2001) and these values are shown in Fig. 3. The almost Wiberg bond indices, except that of the C1—N1 bond, in (I) tend to be lower than those in (II). This may be due to the electron-withdrawing Cl on the C3 instead of H, and decreases the electron density on the five-membered ring. These results correspond to the higher activity of (I) as a biocide compared to that of (II) since the ease of cleavage of the N1—S1 bond is claimed to give rise to the biocidal activity (Lewis et al., 1973).

Related literature

Some crystal structures that contain the title molecule in cocrystals have been reported previously (Suzuki et al., 1997; Sekine, Jomoto et al., 2003; Sekine, Mitsumori et al., 2003).

For related literature, see: Frisch et al. (2003); Fujii et al. (2005); Glendening et al. (2001); Kato et al. (2007); Lewis et al. (1973); Wiberg (1968).

S2. Experimental

Single crystals of (I) suitable for X-ray diffraction were obtained as follows:

4-Chloro-2-methylisothiazolin-3-one was extracted from 'Kathon WT', which was purchased from Rohm and Hass, by 1,2-dichloroethane and was dried with anhydrous MgSO₄. Crude crystals were obtained by evaporation of the solvents and were recrystallized from ligroin. Elemental analysis, found: C 31.87, H 2.52, N 9.20%; calcd. for C₄H₄ClNOS: C 32.11, H 2.70, N 9.36%.

S3. Refinement

H atoms were placed in calculated positions [C—H = 0.95 & 0.98 Å] and included in the refinement in the riding-model approximation with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(C) for methyl H atoms.

Computing details

Data collection: SMART-W2K/NT (Bruker, 2003); cell refinement: SAINT-W2K/NT (Bruker, 2003); data reduction: SAINT-W2K/NT; program(s) used to solve structure: SHELXTL-NT (Bruker, 2003); program(s) used to refine structure: SHELXTL-NT; molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXTL-NT.

Figures

	Fig. 1. The molecular structure the title compound with the atom-numbering scheme. Displacement ellipsoids are shown at the 50% probability level.
	Fig. 2. Diagram showing the intermolecular C=O···Cl—C interactions (dashed line).
	Fig. 3. Wiberg bond indecies in (I) (left) and (II) (right).

5-Chloro-2-methylisothiazolin-3-one

Crystal data

C4H4ClNOS	F(000) = 304
Mr = 149.59	Dx = 1.621 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 824 reflections
a = 8.0290 (16) Å	θ = 2.7–24.8°
b = 13.978 (3) Å	µ = 0.86 mm^−1
c = 5.7375 (11) Å	T = 173 K
β = 107.812 (4)°	Needle, colorless
V = 613.1 (2) Å^3	0.40 × 0.09 × 0.09 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer	1474 independent reflections
Radiation source: fine-focus sealed tube	1157 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.044
Detector resolution: 8.366 pixels mm^-1	θmax = 28.0°, θmin = 2.7°
φ and ω scans	h = −10→10
Absorption correction: multi-scan (SADABS; Sheldrick 1996)	k = −14→18
Tmin = 0.726, Tmax = 0.927	l = −7→7
4451 measured reflections

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.098	H-atom parameters constrained
S = 1.00	w = 1/[σ^2(Fo^2) + (0.0484P)^2] where P = (Fo^2 + 2Fc^2)/3
1474 reflections	(Δ/σ)max = 0.001
74 parameters	Δρmax = 0.33 e Å^−3
0 restraints	Δρmin = −0.27 e Å^−3

Special details

Geometry. Distance SDEV

2.9811 (0.0019) O1 - Cl1_$1

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

- 0.2147 (0.0078) x + 12.2058 (0.0061) y - 2.6112 (0.0038) z = 5.0659 (0.0082)

* -0.0061 (0.0013) C1 * -0.0006 (0.0014) C2 * 0.0052 (0.0013) C3 * 0.0086 (0.0012) N1 * -0.0071 (0.0010) S1 - 0.0161 (0.0029) O1 - 0.2214 (0.0036) C4 0.0272 (0.0032) Cl1

Rms deviation of fitted atoms = 0.0061

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
C1	0.5852 (3)	0.59959 (15)	0.8169 (4)	0.0214 (5)
C2	0.4002 (3)	0.57570 (16)	0.7183 (4)	0.0222 (5)
H1	0.3505	0.5427	0.5683	0.027*
C3	0.3088 (3)	0.60554 (16)	0.8631 (4)	0.0229 (5)
C4	0.7856 (3)	0.66864 (17)	1.2057 (4)	0.0287 (6)
H2A	0.8755	0.6419	1.1412	0.043*
H2B	0.7960	0.6397	1.3651	0.043*
H2C	0.8014	0.7380	1.2246	0.043*
Cl1	0.08933 (8)	0.59406 (5)	0.81908 (12)	0.0338 (2)
N1	0.6122 (2)	0.64805 (13)	1.0356 (4)	0.0229 (4)
O1	0.7041 (2)	0.58234 (11)	0.7303 (3)	0.0289 (4)
S1	0.43218 (8)	0.66265 (4)	1.12464 (11)	0.02660 (19)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0250 (12)	0.0201 (11)	0.0199 (12)	−0.0007 (9)	0.0080 (10)	0.0019 (9)
C2	0.0236 (12)	0.0230 (12)	0.0192 (12)	−0.0016 (9)	0.0051 (10)	−0.0019 (9)
C3	0.0206 (12)	0.0241 (12)	0.0239 (12)	−0.0002 (9)	0.0067 (10)	0.0021 (9)
C4	0.0272 (14)	0.0339 (14)	0.0231 (13)	−0.0033 (11)	0.0049 (11)	−0.0032 (10)
Cl1	0.0209 (3)	0.0439 (4)	0.0370 (4)	0.0012 (3)	0.0094 (3)	0.0014 (3)
N1	0.0209 (10)	0.0271 (11)	0.0210 (10)	−0.0021 (8)	0.0069 (8)	−0.0039 (8)
O1	0.0247 (9)	0.0386 (10)	0.0253 (10)	−0.0027 (7)	0.0103 (7)	−0.0061 (7)
S1	0.0271 (3)	0.0308 (4)	0.0248 (3)	−0.0009 (3)	0.0123 (3)	−0.0056 (2)

Geometric parameters (Å, º)

C1—O1	1.227 (3)	C3—S1	1.721 (2)
C1—N1	1.383 (3)	C4—N1	1.464 (3)
C1—C2	1.458 (3)	C4—H2A	0.9800
C2—C3	1.332 (3)	C4—H2B	0.9800
C2—H1	0.9500	C4—H2C	0.9800
C3—Cl1	1.710 (2)	N1—S1	1.686 (2)
O1—C1—N1	122.5 (2)	N1—C4—H2B	109.5
O1—C1—C2	128.7 (2)	H2A—C4—H2B	109.5
N1—C1—C2	108.8 (2)	N1—C4—H2C	109.5
C3—C2—C1	112.1 (2)	H2A—C4—H2C	109.5
C3—C2—H1	123.9	H2B—C4—H2C	109.5
C1—C2—H1	123.9	C1—N1—C4	123.7 (2)
C2—C3—Cl1	128.16 (19)	C1—N1—S1	115.04 (16)
C2—C3—S1	114.15 (18)	C4—N1—S1	120.17 (16)
Cl1—C3—S1	117.69 (14)	N1—S1—C3	89.86 (10)
N1—C4—H2A	109.5
O1—C1—C2—C3	179.8 (2)	O1—C1—N1—S1	−178.96 (17)
N1—C1—C2—C3	−0.5 (3)	C2—C1—N1—S1	1.3 (2)
C1—C2—C3—Cl1	179.39 (17)	C1—N1—S1—C3	−1.33 (17)
C1—C2—C3—S1	−0.4 (3)	C4—N1—S1—C3	−169.62 (18)
O1—C1—N1—C4	−11.1 (3)	C2—C3—S1—N1	0.99 (19)
C2—C1—N1—C4	169.1 (2)	Cl1—C3—S1—N1	−178.85 (14)