2-Trichloromethylthio-1H-iso­indole-1,3(2H)-dione (Folpet)

The title compound (C₉H₄Cl₃NO₂S), commonly known as Folpet, belongs to a group of phthalimides which function as fungicides or can be used in the laboratory as sulfurizing agents. The phthalimide moiety is slightly folded with a dihedral angle of 3.5 (4)°. The molecule participates in C-H...O and Cl...Cl intermolecular interactions.

S1. Comment

The title compound, (I), is a member of a class of N-(trichloromethylthio)phthalimides which function as useful fungicidal, insecticidal and germicidal agents (Hargreaves et al., 1970). We were particularly interested in the utility of (I) as a convenient sulfurizing agent in the synthesis of dihydrooxathiin complexes. For example, the reaction shown below gives the synthetic route for the preparation of 2,2-bis(4-methoxyphenyl)-2,3-dihydrophenanthro[9,10 − b]-1,4-dioxine using (I) (Carle, 1997). [NB: Scheme shows 1,4-oxathiine not 1,4-dioxine]

The structure of (I) (Fig. 1) resembles other functionalized phthalimides, namely N-trichloromethylthio-3a,4,7,7a-tetrahydrophthalimide (Captan; Moss & Jacobson, 1981), N-(2-nitrophenylthio)phthalimide (Iwasaki & Masuko, 1986) and N-tert-butyldithiophthalimide (Mazhar-ul-Haque & Behforouz, 1979). The thiophthalimido group is slightly folded, with a dihedral angle of 3.5 (4)° between the N1/C2/C3/C8/C9 and C3–C8 planes, whereas nitrophenyl- and butyldithiophthalimide are more planar with corresponding angles of 1.4 and 1.5°, respectively. The S—N bond length [1.668 (5) Å] is shorter than similar bonds in the above related compounds [1.689 (3)–1.702 (2) Å], but is consistent with previously observed S—N single bonds (1.63–1.68 Å) exhibiting π character (Iwasaki & Masuko, 1986).

An intermolecular interaction of the C—H···O═C type (Fig. 2)is observed between the aromatic C atoms of the phthalimide moiety and the symmetry-related carbonyls [C4—H4···O1ⁱ 3.297 (7) Å and 152.5 (2)°; C7—H7···O2ⁱⁱ 3.619 (8) Å and 166.9 (2)°; symmetry codes: (i) −x, 1 − y, 1 − z; (ii) −x, y − 1/2, 1/2 − z]. The H···O distances of 2.44 and 2.71 Å, respectively, are in the range that some consider to be moderate to weak non-conventional hydrogen bonding (Taylor & Kennard, 1982; Steiner, 1996; Jeffrey, 1997). Similar interactions are observed for Captan (C···O 3.400–3.445 Å and 133.2–144.9°; Moss & Jacobson, 1981), N-(2-nitrophenylthio)phthalimide (C···O 3.32–3.33 Å and 152–155°; Iwasaki & Masuko, 1986) and N-tert-butyldithiophthalimide (C···O 3.53 Å and 153°; Mazhar-ul-Haque & Behforouz, 1979).

There is one short intermolecular interaction of 3.350 (3) Å between neighboring Cl atoms which is less than the van der Waals distance (Cl radius = 1.75 Å; Bondi, 1964)). Additionally, one borderline Cl···Cl interaction is observed with a distance of 3.529 (2) Å, which is slightly longer than the van der Waals distance. The corresponding closest contact distance between Cl atoms in Captan is 3.556 Å (Moss & Jacobson, 1981). In Folpet, the nearest-neighbor contact between Cl and S atoms is Cl3···S of 3.675 (2) Å.

S2. Experimental

A heptane solution of trichloromethanesulfenyl chloride was added dropwise to a stirred dimethylformamide solution of phthalimide and triethylamine producing (I) (Wunderly, 1972). Crystals of (I) were obtained by slow evaporation from CH₂Cl₂ at 298 K and was fully characterized by spectroscopic techniques. ¹H NMR (250 MHz, CDCl₃): δ 7.88–7.93 (m, 2H), 8.02–8.07 (m, 2H) p.p.m.; ¹³C NMR (63 MHz, CDCl₃): δ 99.11, 124.65, 131.30, 135.44, 165.77 p.p.m.; IR (CH₂Cl₂): 3948 (m), 3692–3750 (w), 3054 (versus), 2987 (s), 2681 (m), 2410 (m), 2306(s), 1798 (w), 1752 (s), 1721 (w), 1422 (s), 1259 (versus), 1150 (m), 1026 (w), 896 (s), 763 (versus), 711 (versus) cm⁻¹; UV/vis (CH₂Cl₂): λ 239, 296 nm; HRMS (EI): m/z 295 (M⁺), 260, 241, 150, 130, 114, 104, 79, 70; exact mass for C₉H₄Cl₃NO₂S calculated 294.903, found 294.898; m.p. 448–449 K.

Computing details

Data collection: P3-P4/PC (Siemens, 1989); cell refinement: P3-P4/PC; data reduction: XDISK (Siemens, 1989); program(s) used to solve structure: SHELXTL (Sheldrick, 1994); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The structure of (I) showing 50% probability displacement ellipsoids and the atomic numbering scheme.
	Fig. 2. Packing diagram of (I) illustrating the C—H···O interactions in the bc plane.

2-[(trichloromethyl)thio]-1H-isoindole-1,3(2H)-dione

Crystal data

C9H4Cl3NO2S	Dx = 1.780 Mg m^−3
Mr = 296.54	Melting point = 448–449 K
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 9.7666 (19) Å	Cell parameters from 25 reflections
b = 5.7576 (12) Å	θ = 7.5–15.0°
c = 19.754 (3) Å	µ = 1.00 mm^−1
β = 94.905 (14)°	T = 298 K
V = 1106.8 (4) Å^3	Rod, colorless
Z = 4	0.45 × 0.30 × 0.25 mm
F(000) = 592

Data collection

Siemens P3 diffractometer	Rint = 0.035
Radiation source: normal-focus sealed tube	θmax = 27.6°, θmin = 1.5°
Graphite monochromator	h = 0→12
θ–2θ scans	k = 0→7
2702 measured reflections	l = −25→25
2554 independent reflections	3 standard reflections every 250 reflections
1281 reflections with I > 2σ(I)	intensity decay: none

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)] = 0.061	H-atom parameters constrained
wR(F^2) = 0.157	w = 1/[σ^2(Fo^2) + (0.0533P)^2 + 1.2199P] where P = (Fo^2 + 2Fc^2)/3
S = 1.10	(Δ/σ)max < 0.001
2552 reflections	Δρmax = 0.40 e Å^−3
146 parameters	Δρmin = −0.52 e Å^−3
0 restraints	Extinction correction: SHELXTL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.022 (2)

Special details

Experimental. The data was corrected for decay (min. 0.9549, max. 1.000). These data were collected using variable speed θ–2θ scans (3.0–20.0°/ min), and corrected for decay (min. 0.955, max. 1.00), Lorentz, polarization and extinction effects but not for absorption

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 on F² for ALL reflections except for 2 with very negative F² or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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-factor(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.

The structure was solved by direct methods, expanded by difference Fourier techniques and refined by full-matrix least squares on F². H-atom positions were calculated based on geometric criterion (C—H=0.93 Å) and allowed to ride on their respective atoms. H-atom U values were assigned as 1.2U_eq of the adjacent atom.

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

	x	y	z	Uiso*/Ueq
S1	0.2997 (2)	0.2927 (3)	0.29936 (7)	0.0450 (4)
O1	0.1391 (5)	0.4883 (7)	0.4127 (2)	0.0569 (12)
O2	0.1146 (5)	−0.1377 (7)	0.2678 (2)	0.0546 (12)
Cl1	0.4283 (2)	−0.1228 (2)	0.36806 (8)	0.0560 (5)
Cl2	0.4569 (2)	0.3122 (3)	0.43701 (7)	0.0536 (5)
Cl3	0.5867 (2)	0.2517 (3)	0.31233 (7)	0.0557 (5)
N1	0.1642 (5)	0.1895 (8)	0.3357 (2)	0.0414 (11)
C2	0.0975 (7)	0.3066 (10)	0.3879 (3)	0.0460 (15)
C3	−0.0174 (6)	0.1586 (9)	0.4029 (3)	0.0413 (14)
C4	−0.1093 (7)	0.1870 (12)	0.4520 (3)	0.052 (2)
H4	−0.1065 (7)	0.3170 (12)	0.4800 (3)	0.063*
C5	−0.2048 (7)	0.0137 (14)	0.4573 (3)	0.062 (2)
H5	−0.2673 (7)	0.0267 (14)	0.4901 (3)	0.074*
C6	−0.2106 (7)	−0.1796 (12)	0.4154 (3)	0.057 (2)
H6	−0.2760 (7)	−0.2938 (12)	0.4210 (3)	0.068*
C7	−0.1203 (7)	−0.2059 (11)	0.3650 (3)	0.051 (2)
H7	−0.1247 (7)	−0.3340 (11)	0.3362 (3)	0.061*
C8	−0.0246 (6)	−0.0338 (10)	0.3600 (3)	0.0391 (14)
C9	0.0879 (7)	−0.0155 (10)	0.3142 (3)	0.0434 (14)
C10	0.4403 (7)	0.1787 (9)	0.3558 (3)	0.0424 (14)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0602 (10)	0.0394 (8)	0.0345 (7)	0.0008 (8)	−0.0007 (7)	0.0069 (6)
O1	0.067 (3)	0.040 (2)	0.064 (3)	0.004 (2)	0.004 (2)	−0.016 (2)
O2	0.071 (3)	0.052 (2)	0.041 (2)	−0.004 (2)	0.005 (2)	−0.014 (2)
Cl1	0.0765 (12)	0.0294 (7)	0.0603 (10)	0.0012 (8)	−0.0040 (8)	0.0045 (7)
Cl2	0.0744 (11)	0.0508 (9)	0.0347 (7)	−0.0029 (8)	−0.0005 (7)	−0.0102 (7)
Cl3	0.0611 (10)	0.0606 (10)	0.0466 (8)	−0.0027 (9)	0.0109 (7)	0.0063 (7)
N1	0.055 (3)	0.034 (2)	0.035 (2)	0.000 (2)	0.001 (2)	−0.002 (2)
C2	0.060 (4)	0.040 (3)	0.037 (3)	0.012 (3)	−0.003 (3)	−0.002 (3)
C3	0.050 (4)	0.037 (3)	0.036 (3)	0.012 (3)	−0.002 (3)	0.003 (2)
C4	0.066 (4)	0.053 (4)	0.038 (3)	0.016 (4)	0.003 (3)	0.002 (3)
C5	0.054 (4)	0.081 (5)	0.051 (4)	0.024 (4)	0.012 (3)	0.014 (4)
C6	0.054 (4)	0.056 (4)	0.059 (4)	0.003 (4)	−0.005 (3)	0.021 (3)
C7	0.058 (4)	0.042 (3)	0.049 (3)	0.003 (3)	−0.012 (3)	0.001 (3)
C8	0.049 (4)	0.038 (3)	0.029 (3)	0.009 (3)	−0.002 (3)	0.004 (2)
C9	0.060 (4)	0.034 (3)	0.034 (3)	0.010 (3)	−0.007 (3)	0.002 (3)
C10	0.062 (4)	0.032 (3)	0.033 (3)	−0.001 (3)	0.005 (3)	−0.003 (2)

Geometric parameters (Å, º)

S1—N1	1.668 (5)	C2—C3	1.460 (9)
S1—C10	1.816 (6)	C3—C4	1.386 (8)
O1—C2	1.211 (7)	C3—C8	1.394 (7)
O2—C9	1.201 (6)	C4—C5	1.376 (9)
Cl1—C10	1.758 (5)	C5—C6	1.386 (9)
Cl2—C10	1.774 (5)	C6—C7	1.393 (9)
Cl3—C10	1.780 (6)	C7—C8	1.372 (8)
N1—C2	1.434 (7)	C8—C9	1.485 (8)
N1—C9	1.440 (7)
N1—S1—C10	101.2 (2)	C8—C7—C6	116.8 (6)
C2—N1—C9	110.0 (5)	C7—C8—C3	121.9 (6)
C2—N1—S1	124.6 (4)	C7—C8—C9	129.8 (5)
C9—N1—S1	125.1 (4)	C3—C8—C9	108.2 (5)
O1—C2—N1	122.7 (6)	O2—C9—N1	124.3 (6)
O1—C2—C3	131.2 (6)	O2—C9—C8	130.0 (6)
N1—C2—C3	106.0 (5)	N1—C9—C8	105.7 (5)
C4—C3—C8	121.2 (6)	Cl1—C10—Cl2	107.8 (3)
C4—C3—C2	129.0 (5)	Cl1—C10—Cl3	111.5 (3)
C8—C3—C2	109.8 (5)	Cl2—C10—Cl3	108.6 (3)
C5—C4—C3	116.8 (6)	Cl1—C10—S1	112.7 (3)
C4—C5—C6	122.0 (6)	Cl2—C10—S1	113.8 (3)
C5—C6—C7	121.2 (7)	Cl3—C10—S1	102.4 (3)
C10—S1—N1—C2	89.0 (5)	C6—C7—C8—C9	177.3 (6)
C10—S1—N1—C9	−98.5 (5)	C4—C3—C8—C7	−1.4 (9)
C9—N1—C2—O1	−177.4 (5)	C2—C3—C8—C7	177.5 (5)
S1—N1—C2—O1	−3.9 (8)	C4—C3—C8—C9	−179.2 (5)
C9—N1—C2—C3	4.7 (6)	C2—C3—C8—C9	−0.4 (6)
S1—N1—C2—C3	178.2 (4)	C2—N1—C9—O2	174.5 (5)
O1—C2—C3—C4	−1.5 (10)	S1—N1—C9—O2	1.0 (8)
N1—C2—C3—C4	176.1 (5)	C2—N1—C9—C8	−4.9 (6)
O1—C2—C3—C8	179.7 (6)	S1—N1—C9—C8	−178.4 (4)
N1—C2—C3—C8	−2.6 (6)	C7—C8—C9—O2	6.3 (10)
C8—C3—C4—C5	1.7 (8)	C3—C8—C9—O2	−176.1 (6)
C2—C3—C4—C5	−177.0 (5)	C7—C8—C9—N1	−174.4 (5)
C3—C4—C5—C6	−0.6 (9)	C3—C8—C9—N1	3.2 (6)
C4—C5—C6—C7	−0.7 (10)	N1—S1—C10—Cl1	52.5 (3)
C5—C6—C7—C8	1.1 (9)	N1—S1—C10—Cl2	−70.6 (3)
C6—C7—C8—C3	0.0 (8)	N1—S1—C10—Cl3	172.4 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4···O1^i	0.93	2.44	3.295 (7)	153
C7—H7···O2^ii	0.93	2.71	3.619 (8)	167

Symmetry codes: (i) −x, y+3/2, −z+3/2; (ii) −x, −y−1, −z.