trans-3,6-Bis­(chloro­phenyl­methyl­ene)-1,2,4,5-tetra­thia­ne

The title compound, C₁₆H₁₀Cl₂S₄, contains a tetra­thia­ne ring that displays a twist conformation. The S—S bond lengths are 2.049 (2) and 2.046 (2) Å. At the methyl­ene C atoms, the C—C—C angles are by far the largest, with values of 127.7 (3) and 126.8 (4)°. The packing involves C—H...S, C—H...Cl and Cl...Cl interactions.

Key indicators

• Single-crystal X-ray study
• T = 133 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.049
• wR factor = 0.140
• Data-to-parameter ratio = 14.3

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level A:



DIFF_012  Alert A _diffrn_reflns_av_R_equivalents is missing
          R factor for symmetry-equivalent intensities.
          The following tests will not be performed
          RINTA


 Alert Level C:



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           25.05
         From the CIF: _reflns_number_total               2845
         TEST2: Reflns within _diffrn_reflns_theta_max
         Count of symmetry unique reflns         3017
         Completeness (_total/calc)             94.30%
          Alert C: < 95% complete


 1 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 1 Alert Level C = Please check

---

S1. Comment

The reaction of carbenes with CS₂ is not well understood. Several diazo compounds and diazirines have been shown to react thermally (at room or elevated temperatures) with CS₂ with loss of N₂ and formation of 1,2,4,5-tetrathianes (Raasch, 1970; Schoenberg et al., 1962). Loss of nitrogen from the precursors used in these experiments leads to triplet carbenes; however, it is not clear if the carbenes or the precursors react with CS₂. We therefore investigated the photochemical reaction of phenylchlorodiazirine (2), which is the precursor of the singlet carbene (1), with CS₂.

At room temperature, a solution of (2) in CS₂ becomes dark red within several hours, while at 238 K, these solutions are stable. UV irradiation (λ > 350 nm) at 238 K results in the formation of an intense red solution, from which the yellow title compound (3) can be isolated in 15% yield.

A plausible mechanism is shown in the Scheme. Photolysis of (2) results in the formation of carbene (1), which is trapped by CS₂. The methylenedithiirane (4) might then ring-open (either photochemically or in a thermal equilibrium) to give biradical (5). Dimerization of (5) finally produces (3). However, there is no direct evidence for the intermediates (1), (4) and (5), and so the mechanism remains speculative.

The X-ray investigation of the product (3) confirmed the proposed structure, with a trans disposition of the methylene substituents (Fig. 1). Despite the formal symmetry of the chemical formula, the molecule shows no crystallographic symmetry. The tetrathiane ring displays a slightly distorted twist conformation with local twofold axes, one along the direction C1···C2 and the other between the midpoints of S1—S3 and S2—S4. The dimensions of the ring (Table 1) may be considered normal, and are closely similar to those of the only other bis(methylene)-substituted 1,2,4,5-tetrathiane found in a search of the Cambridge Structural Database (Version of October, 2001; Allen & Kennard, 1993), namely the bis(dimesitylmethylene) derivative (Selzer & Rappoport, 1996). The angles around the methylene C atoms, amongst which the C—C—C angles are much the largest, reflect the higher electronegativity of the chlorine substituents.

The crystal packing shows two types of short contacts, three possible weak hydrogen bonds C—H···S and one C—H···Cl (Table 2), and a Cl2···Cl2 contact [symmetry code: 2 - x, 1 - y, 1 - z; Cl···Cl 3.475 (2) Å and C—Cl···Cl 132.01 (14)°]. We note, however, that the hydrogen bonds represent at best borderline cases, cf. sum of van der Waals radii H + Cl = 2.95 Å and H+S = 3.00 Å (Bondi, 1964).

S2. Experimental

Preparation of (3): 870 mg (5.7 mmol) (2) were dissolved in 25 ml dry CS₂ and cooled to liquid-nitrogen temperature. The solution was degassed three times by allowing it to warm slightly in vacuo. Despite the low temperature, the solution became slightly yellow. It was then irradiated with UV light (λ = 380±20 nm) for 4 h at 238 K in a 25 ml quarz cuvette fitted with a cooling mantle. The resulting red solution was subjected to column chromatography on silica with hexane as eluent, yielding 180 mg (15%) of a yellow oil (m.p. 414–415 K). Spectroscopic details are given by Wierlacher (1993). Analysis: calculated C 47.87, H 2.51, S 31.95%; found C 47.97, H 2.51, S 31.68%. Single crystals were obtained from saturated solutions in hexane.

S3. Refinement

H atoms were placed in idealized positions and refined using a riding model.

Computing details

Data collection: DIF4 (Stoe & Cie, 1992); cell refinement: DIF4; data reduction: REDU4 (Stoe & Cie, 1992); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Siemens, 1994); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. The molecular structure of the title compound in the crystal. Ellipsoids represent 50% probability levels.

trans-3,6-Bis(chlorophenylmethylene)-1,2,4,5-tetrathiane

Crystal data

C16H10Cl2S4	Dx = 1.563 Mg m^−3
Mr = 401.38	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 48 reflections
a = 7.611 (4) Å	θ = 10–11.2°
b = 17.137 (5) Å	µ = 0.86 mm^−1
c = 26.161 (10) Å	T = 133 K
V = 3412 (2) Å^3	Prism, yellow
Z = 8	0.6 × 0.4 × 0.4 mm
F(000) = 1632

Data collection

Stoe STADI-4 diffractometer	θmax = 25.1°, θmin = 3.0°
Radiation source: fine-focus sealed tube	h = −9→0
Graphite monochromator	k = 0→20
ω/θ scans	l = 0→31
2845 measured reflections	3 standard reflections every 60 min
2845 independent reflections	intensity decay: none
2414 reflections with I > 2σ(I)

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)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.140	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0776P)^2 + 7.2011P] where P = (Fo^2 + 2Fc^2)/3
2845 reflections	(Δ/σ)max < 0.001
199 parameters	Δρmax = 0.38 e Å^−3
0 restraints	Δρmin = −0.46 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.

Non-bonded contact:

3.4755 (0.0023) Cl2 - Cl2_$1 132.01 (0.14) C4 - Cl2 - Cl2_$1 Operator: $1 2 - x,1 - y,1 - z

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
S1	0.60339 (13)	0.48438 (5)	0.34817 (3)	0.0284 (3)
S2	0.46901 (14)	0.64959 (5)	0.34243 (4)	0.0326 (3)
S3	0.76821 (12)	0.54307 (5)	0.39669 (3)	0.0282 (2)
S4	0.40854 (13)	0.61150 (6)	0.41441 (4)	0.0326 (3)
Cl1	0.42775 (15)	0.64014 (5)	0.22748 (4)	0.0372 (3)
Cl2	0.87739 (14)	0.58501 (7)	0.50623 (4)	0.0441 (3)
C1	0.5216 (5)	0.5618 (2)	0.31008 (13)	0.0242 (7)
C2	0.6188 (5)	0.5893 (2)	0.43936 (13)	0.0252 (8)
C3	0.5001 (5)	0.5560 (2)	0.25935 (13)	0.0266 (8)
C4	0.6657 (5)	0.6094 (2)	0.48640 (13)	0.0266 (8)
C5	0.5323 (5)	0.4880 (2)	0.22703 (13)	0.0257 (7)
C6	0.4831 (5)	0.4139 (2)	0.24334 (14)	0.0313 (8)
H6	0.4261	0.4075	0.2754	0.038*
C7	0.5170 (6)	0.3491 (2)	0.21298 (15)	0.0388 (10)
H7	0.4846	0.2986	0.2245	0.047*
C8	0.5980 (6)	0.3581 (2)	0.16587 (16)	0.0396 (10)
H8	0.6221	0.3137	0.1453	0.047*
C9	0.6434 (5)	0.4315 (2)	0.14901 (14)	0.0348 (9)
H9	0.6982	0.4376	0.1166	0.042*
C10	0.6099 (5)	0.4963 (2)	0.17885 (14)	0.0293 (8)
H10	0.6397	0.5468	0.1666	0.035*
C11	0.5577 (5)	0.6518 (2)	0.52431 (13)	0.0267 (8)
C12	0.3871 (5)	0.6285 (2)	0.53414 (14)	0.0317 (8)
H12	0.3391	0.5849	0.5166	0.038*
C13	0.2855 (5)	0.6687 (2)	0.56963 (15)	0.0363 (9)
H13	0.1679	0.6528	0.5759	0.044*
C14	0.3545 (6)	0.7315 (2)	0.59585 (15)	0.0381 (9)
H14	0.2853	0.7585	0.6203	0.046*
C15	0.5254 (6)	0.7547 (3)	0.58616 (17)	0.0428 (10)
H15	0.5728	0.7983	0.6039	0.051*
C16	0.6270 (5)	0.7157 (2)	0.55136 (15)	0.0359 (9)
H16	0.7447	0.7318	0.5455	0.043*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0381 (6)	0.0253 (5)	0.0217 (5)	0.0023 (4)	−0.0019 (4)	−0.0021 (3)
S2	0.0431 (6)	0.0259 (5)	0.0287 (5)	0.0053 (4)	−0.0080 (4)	−0.0049 (4)
S3	0.0273 (5)	0.0352 (5)	0.0220 (5)	0.0040 (4)	0.0010 (4)	−0.0046 (3)
S4	0.0274 (5)	0.0438 (6)	0.0265 (5)	0.0066 (4)	−0.0025 (4)	−0.0090 (4)
Cl1	0.0499 (6)	0.0297 (5)	0.0322 (5)	0.0019 (4)	−0.0116 (4)	0.0021 (4)
Cl2	0.0345 (5)	0.0687 (7)	0.0290 (5)	0.0164 (5)	−0.0078 (4)	−0.0083 (5)
C1	0.0245 (18)	0.0258 (17)	0.0223 (17)	−0.0011 (14)	−0.0016 (14)	−0.0029 (13)
C2	0.0282 (19)	0.0275 (17)	0.0198 (17)	0.0028 (14)	0.0011 (14)	−0.0019 (14)
C3	0.0297 (18)	0.0261 (17)	0.0240 (18)	−0.0022 (15)	−0.0031 (15)	0.0047 (14)
C4	0.0285 (19)	0.0317 (18)	0.0195 (17)	0.0002 (15)	−0.0019 (15)	0.0014 (14)
C5	0.0281 (19)	0.0285 (18)	0.0205 (17)	0.0000 (15)	−0.0057 (14)	−0.0031 (14)
C6	0.038 (2)	0.0345 (19)	0.0214 (17)	−0.0046 (16)	−0.0010 (16)	0.0006 (15)
C7	0.055 (3)	0.030 (2)	0.032 (2)	−0.0052 (18)	0.000 (2)	−0.0044 (16)
C8	0.048 (3)	0.038 (2)	0.033 (2)	−0.0015 (18)	−0.0030 (19)	−0.0117 (18)
C9	0.035 (2)	0.049 (2)	0.0200 (18)	−0.0015 (18)	−0.0026 (15)	−0.0052 (16)
C10	0.0290 (19)	0.0334 (19)	0.0255 (19)	−0.0044 (15)	−0.0052 (15)	0.0005 (15)
C11	0.033 (2)	0.0305 (18)	0.0163 (16)	0.0023 (15)	0.0017 (15)	0.0045 (13)
C12	0.034 (2)	0.0329 (19)	0.0281 (19)	−0.0037 (16)	0.0028 (16)	0.0004 (16)
C13	0.030 (2)	0.048 (2)	0.031 (2)	0.0013 (17)	0.0070 (17)	0.0008 (17)
C14	0.044 (2)	0.041 (2)	0.030 (2)	0.0105 (19)	0.0067 (18)	−0.0071 (17)
C15	0.045 (3)	0.040 (2)	0.043 (2)	0.0001 (19)	0.003 (2)	−0.0177 (18)
C16	0.033 (2)	0.040 (2)	0.035 (2)	−0.0030 (17)	0.0015 (17)	−0.0079 (17)

Geometric parameters (Å, º)

S1—C1	1.772 (4)	C7—H7	0.9500
S1—S3	2.049 (2)	C8—C9	1.377 (6)
S2—C1	1.772 (3)	C8—H8	0.9500
S2—S4	2.046 (2)	C9—C10	1.382 (5)
S3—C2	1.780 (4)	C9—H9	0.9500
S4—C2	1.770 (4)	C10—H10	0.9500
Cl1—C3	1.754 (4)	C11—C12	1.382 (5)
Cl2—C4	1.743 (4)	C11—C16	1.406 (5)
C1—C3	1.341 (5)	C12—C13	1.391 (5)
C2—C4	1.327 (5)	C12—H12	0.9500
C3—C5	1.460 (5)	C13—C14	1.380 (6)
C4—C11	1.479 (5)	C13—H13	0.9500
C5—C6	1.392 (5)	C14—C15	1.383 (6)
C5—C10	1.399 (5)	C14—H14	0.9500
C6—C7	1.388 (5)	C15—C16	1.369 (6)
C6—H6	0.9500	C15—H15	0.9500
C7—C8	1.386 (6)	C16—H16	0.9500
C1—S1—S3	101.3 (1)	C9—C8—H8	120.1
C1—S2—S4	102.7 (1)	C7—C8—H8	120.1
C2—S3—S1	102.5 (1)	C8—C9—C10	120.5 (4)
C2—S4—S2	101.8 (1)	C8—C9—H9	119.8
C3—C1—S1	123.0 (3)	C10—C9—H9	119.8
C3—C1—S2	120.5 (3)	C9—C10—C5	120.4 (3)
S1—C1—S2	116.5 (2)	C9—C10—H10	119.8
C4—C2—S4	122.0 (3)	C5—C10—H10	119.8
C4—C2—S3	121.7 (3)	C12—C11—C16	118.9 (3)
S4—C2—S3	116.2 (2)	C12—C11—C4	120.3 (3)
C1—C3—C5	127.7 (3)	C16—C11—C4	120.8 (3)
C1—C3—Cl1	116.6 (3)	C11—C12—C13	120.2 (4)
C5—C3—Cl1	115.7 (3)	C11—C12—H12	119.9
C2—C4—C11	126.8 (4)	C13—C12—H12	119.9
C2—C4—Cl2	117.6 (3)	C14—C13—C12	120.4 (4)
C11—C4—Cl2	115.6 (3)	C14—C13—H13	119.8
C6—C5—C10	118.8 (3)	C12—C13—H13	119.8
C6—C5—C3	120.4 (3)	C13—C14—C15	119.4 (4)
C10—C5—C3	120.8 (3)	C13—C14—H14	120.3
C7—C6—C5	120.3 (4)	C15—C14—H14	120.3
C7—C6—H6	119.9	C16—C15—C14	120.8 (4)
C5—C6—H6	119.9	C16—C15—H15	119.6
C8—C7—C6	120.2 (4)	C14—C15—H15	119.6
C8—C7—H7	119.9	C15—C16—C11	120.2 (4)
C6—C7—H7	119.9	C15—C16—H16	119.9
C9—C8—C7	119.9 (4)	C11—C16—H16	119.9
C1—S1—S3—C2	75.0 (2)	Cl1—C3—C5—C10	39.1 (4)
C1—S2—S4—C2	74.5 (2)	C10—C5—C6—C7	2.4 (6)
S3—S1—C1—C3	138.6 (3)	C3—C5—C6—C7	−178.7 (4)
S3—S1—C1—S2	−41.0 (2)	C5—C6—C7—C8	−0.9 (6)
S4—S2—C1—C3	153.0 (3)	C6—C7—C8—C9	−0.6 (7)
S4—S2—C1—S1	−27.4 (2)	C7—C8—C9—C10	0.4 (6)
S2—S4—C2—C4	136.5 (3)	C8—C9—C10—C5	1.2 (6)
S2—S4—C2—S3	−40.3 (2)	C6—C5—C10—C9	−2.6 (5)
S1—S3—C2—C4	155.1 (3)	C3—C5—C10—C9	178.6 (3)
S1—S3—C2—S4	−28.2 (2)	C2—C4—C11—C12	48.5 (5)
S1—C1—C3—C5	2.0 (6)	Cl2—C4—C11—C12	−132.4 (3)
S2—C1—C3—C5	−178.3 (3)	C2—C4—C11—C16	−132.4 (4)
S1—C1—C3—Cl1	−177.0 (2)	Cl2—C4—C11—C16	46.8 (4)
S2—C1—C3—Cl1	2.7 (4)	C16—C11—C12—C13	1.1 (6)
S4—C2—C4—C11	−0.2 (5)	C4—C11—C12—C13	−179.7 (3)
S3—C2—C4—C11	176.3 (3)	C11—C12—C13—C14	−0.9 (6)
S4—C2—C4—Cl2	−179.3 (2)	C12—C13—C14—C15	0.7 (6)
S3—C2—C4—Cl2	−2.8 (4)	C13—C14—C15—C16	−0.7 (7)
C1—C3—C5—C6	41.3 (6)	C14—C15—C16—C11	1.0 (7)
Cl1—C3—C5—C6	−139.7 (3)	C12—C11—C16—C15	−1.2 (6)
C1—C3—C5—C10	−139.9 (4)	C4—C11—C16—C15	179.7 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8···S2^i	0.95	2.91	3.616 (4)	132
C14—H14···S2^ii	0.95	3.04	3.920 (4)	155
C15—H15···S4^iii	0.95	3.02	3.710 (5)	130
C9—H9···Cl2^iv	0.95	2.97	3.749 (4)	140

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