Monoclinic form of (E)-1,2-bis­(methyl­thio)-1,2-di­phenyl­ethyl­ene

The structure of a new monoclinic polymorph of the title compound, C₁₆H₁₆S₂, is reported here. The mol­ecule lies on an inversion centre with an E configuration about the C=C bond.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.044
• wR factor = 0.121
• Data-to-parameter ratio = 16.2

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level A:



DIFF_020  Alert A _diffrn_standards_interval_count and
          _diffrn_standards_interval_time are missing. Number of measurements
          between standards or time (min) between standards.

General Notes



ABSTM_02  When printed, the submitted absorption T values will be replaced
          by the scaled T values. Since the ratio of scaled T's is
          identical to the ratio of reported T values, the scaling does
          not imply a change to the absorption corrections used in the
          study.
          Ratio of Tmax expected/reported      0.932
          Tmax scaled      0.932 Tmin scaled      0.841


 1 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 0 Alert Level C = Please check

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S1. Comment

The title compound, (I), crystallizes in at least two polymorphic forms; the one presented here is monoclinic in space group P2₁/c and the other, in P1, was reported previously (Adiwidjaja et al., 1981). In both polymorphs, the molecules lie about centres of symmetry. In the monoclinic form, the asymmetric unit comprises one half molecule, whereas there are two half molecules in the asymmetric unit of the triclinic unit cell. The structure confirms the E configuration about the C═C bond with the aromatic rings inclined at 58.84 (8)° to the plane of the double bond, precluding any extensive delocalization in the molecular system.

Some significant differences are found between the geometric parameters defining the alkene unit. In particular, the S1—C1, S1—C8 and C1—C1ⁱ bond distances in this structure are significantly longer than those reported for the other polymorph, while the torsion angle C1ⁱ—C1—C2—C3 of -62.3 (3)° is substantially reduced [symmetry code: (i) -x, 1 - y, 1 - z].

Molecules are well separated and stack in a head-to-head fashion along the a axis of the monoclinic unit cell (Fig. 2), with a repeat distance between individual molecules in the stack of 5.2034 (2) Å, the length of the unit cell edge.

S2. Experimental

The title compound was prepared from the reaction of (Ph₂C₂S₂)₂CoP(OCH₃)₃ with an excess of P(OCH₃)₃ in refluxing toluene for 48 h under an argon atmosphere (Rieger & Rieger, 2002). The products were dissolved in CH₂Cl₂ and chromatographed on silica. The title compound was eluted with hexane and recrystallization from methanol/water gave colourless prisms. Found: C 70.45, H 6.16, S 23.44%; C₁₆H₁₆S₂ requires: C 70.54, H 5.92, S 23.54%. EI mass spectrum: m/z 272 (M⁺).

Computing details

Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997) and TITAN2000 (Hunter & Simpson, 1999); program(s) used to refine structure: SHELXL97 and TITAN2000; molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97'.

Figures

	Fig. 1. Perspective drawing of the title molecule (Farrugia, 1997), showing the atom-numbering scheme, with displacement ellipsoids drawn at the 50% probability level. The molecule is centrosymmetric. H atoms are drawn as circles with arbitrary radii.
	Fig. 2. Packing diagram (Farrugia, 1997) of the title compound viewed down the a axis

(E)-1,2-bis(methylthio)-1,2-diphenylethylene

Crystal data

C16H16S2	F(000) = 288
Mr = 272.41	Dx = 1.271 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3211 reflections
a = 5.2034 (2) Å	θ = 2.6–25.7°
b = 8.5978 (3) Å	µ = 0.35 mm^−1
c = 15.9048 (6) Å	T = 150 K
β = 90.112 (1)°	Prisms, colourless
V = 711.54 (5) Å^3	0.24 × 0.20 × 0.20 mm
Z = 2

Data collection

Siemens SMART diffractometer	1346 independent reflections
Radiation source: fine-focus sealed tube	1177 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.000
ω scans	θmax = 25.7°, θmin = 2.6°
Absorption correction: empirical (using intensity measurements) (SADABS; Siemens, 1995)	h = −6→6
Tmin = 0.903, Tmax = 1	k = 0→10
1346 measured reflections	l = 0→19

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) = 0.121	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0918P)^2 + 0.03P] where P = (Fo^2 + 2Fc^2)/3
1346 reflections	(Δ/σ)max < 0.001
83 parameters	Δρmax = 0.46 e Å^−3
0 restraints	Δρmin = −0.72 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.

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	0.02892 (9)	0.24605 (4)	0.48976 (3)	0.0287 (2)
C1	0.0359 (3)	0.44212 (19)	0.52620 (10)	0.0223 (4)
C2	0.1150 (3)	0.46607 (19)	0.61549 (10)	0.0222 (4)
C3	0.3309 (3)	0.5553 (2)	0.63608 (11)	0.0277 (4)
H3	0.4280	0.6035	0.5928	0.033*
C4	0.4045 (3)	0.5738 (2)	0.71980 (12)	0.0338 (4)
H4	0.5493	0.6363	0.7334	0.041*
C5	0.2667 (4)	0.5010 (2)	0.78339 (11)	0.0338 (5)
H5	0.3181	0.5129	0.8404	0.041*
C6	0.0532 (4)	0.4108 (2)	0.76338 (11)	0.0334 (4)
H6	−0.0412	0.3609	0.8067	0.040*
C7	−0.0218 (3)	0.3937 (2)	0.68028 (11)	0.0276 (4)
H7	−0.1680	0.3320	0.6671	0.033*
C8	0.2801 (4)	0.1544 (2)	0.55086 (12)	0.0338 (4)
H8A	0.4429	0.2088	0.5414	0.051*
H8B	0.2974	0.0455	0.5336	0.051*
H8C	0.2360	0.1592	0.6107	0.051*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0337 (3)	0.0227 (3)	0.0296 (3)	0.00139 (15)	−0.0064 (2)	−0.00319 (15)
C1	0.0174 (7)	0.0240 (8)	0.0256 (8)	−0.0010 (6)	0.0025 (6)	−0.0018 (6)
C2	0.0190 (7)	0.0223 (8)	0.0254 (8)	0.0032 (6)	0.0008 (6)	−0.0016 (6)
C3	0.0220 (8)	0.0304 (9)	0.0308 (9)	0.0005 (7)	0.0011 (7)	−0.0003 (7)
C4	0.0272 (9)	0.0348 (10)	0.0395 (10)	−0.0005 (7)	−0.0095 (7)	−0.0049 (8)
C5	0.0385 (10)	0.0377 (11)	0.0250 (9)	0.0073 (8)	−0.0084 (7)	−0.0040 (7)
C6	0.0369 (9)	0.0369 (10)	0.0263 (9)	0.0027 (8)	0.0026 (7)	0.0026 (7)
C7	0.0262 (8)	0.0281 (9)	0.0285 (9)	−0.0018 (7)	0.0005 (6)	0.0004 (7)
C8	0.0300 (9)	0.0297 (9)	0.0417 (10)	0.0080 (8)	−0.0009 (7)	−0.0004 (8)

Geometric parameters (Å, º)

S1—C1	1.7830 (17)	C4—H4	0.9500
S1—C8	1.8078 (18)	C5—C6	1.391 (3)
C1—C1^i	1.350 (3)	C5—H5	0.9500
C1—C2	1.492 (2)	C6—C7	1.385 (2)
C2—C3	1.399 (2)	C6—H6	0.9500
C2—C7	1.400 (2)	C7—H7	0.9500
C3—C4	1.394 (2)	C8—H8A	0.9800
C3—H3	0.9500	C8—H8B	0.9800
C4—C5	1.390 (3)	C8—H8C	0.9800
C1—S1—C8	102.90 (8)	C4—C5—H5	120.1
C1^i—C1—C2	124.13 (19)	C6—C5—H5	120.1
C1^i—C1—S1	119.40 (17)	C7—C6—C5	120.07 (17)
C2—C1—S1	116.44 (12)	C7—C6—H6	120.0
C3—C2—C7	118.75 (16)	C5—C6—H6	120.0
C3—C2—C1	121.22 (14)	C6—C7—C2	120.82 (16)
C7—C2—C1	119.98 (14)	C6—C7—H7	119.6
C4—C3—C2	120.34 (16)	C2—C7—H7	119.6
C4—C3—H3	119.8	S1—C8—H8A	109.5
C2—C3—H3	119.8	S1—C8—H8B	109.5
C5—C4—C3	120.18 (16)	H8A—C8—H8B	109.5
C5—C4—H4	119.9	S1—C8—H8C	109.5
C3—C4—H4	119.9	H8A—C8—H8C	109.5
C4—C5—C6	119.82 (17)	H8B—C8—H8C	109.5
C8—S1—C1—C1^i	150.93 (18)	C3—C4—C5—C6	−0.6 (3)
C8—S1—C1—C2	−30.94 (13)	C4—C5—C6—C7	−0.1 (3)
C1^i—C1—C2—C3	−62.3 (3)	C5—C6—C7—C2	0.1 (3)
S1—C1—C2—C3	119.70 (15)	C3—C2—C7—C6	0.6 (2)
C1^i—C1—C2—C7	120.3 (2)	C1—C2—C7—C6	178.09 (15)
S1—C1—C2—C7	−57.76 (18)	S1—C1—C1^i—S1^i	180.0
C7—C2—C3—C4	−1.3 (2)	S1—C1—C1^i—C2^i	−2.0 (3)
C1—C2—C3—C4	−178.75 (15)	C2—C1—C1^i—S1^i	2.0 (3)
C2—C3—C4—C5	1.3 (3)	C2—C1—C1^i—C2^i	180.000 (1)

Symmetry code: (i) −x, −y+1, −z+1.