2-(1,3-Dithian-2-yl­idene)-1-phenyl­butane-1,3-dione

The title compound, C₁₃H₁₂O₂S₂, belonging to the group of dioxoketene cyclic S,S-acetals, was prepared from the corresponding dione in high yield. In the structure, the C=O and C=C bonds are not coplanar, with O=C-C=C torsion angles of -36.8 (4) and -21.0 (4)°. The dithian ring has a twisted conformation.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.029
• wR factor = 0.074
• Data-to-parameter ratio = 12.6

checkCIF/PLATON results

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Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           25.00
           From the CIF: _reflns_number_total               1948
           Count of symmetry unique reflns         1207
           Completeness (_total/calc)            161.39%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       741
           Fraction of Friedel pairs measured     0.614
           Are heavy atom types Z>Si present        yes
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

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

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

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S1. Comment

The dioxo ketene cyclic S,S-acetals have been known as a precursor for the synthesis of not only unsaturated ketones and keto esters, but also heterocyclic compounds (Choi et al., 1988; Lin et al., 2005; Zhu et al., 1996; Zhu et al., 1997). We have synthesized the title compound, 1-phenyl-2-(1,3-dithian -2-ylidene)-butane-1,3-dione and determined its molecular structure (Fig. 1). In the structure, the C=O bonds, the benzene ring, and the C2=C5 double bond are not co-planar. The O1—C1—C8—C13 torsion angle is -24.3 (4)°. The dihedral angle between the planes C2_C1_O1 and C2_C3_O2 is 50.7 (4)°, and is 7.6 (4) ° between the C1_C2_C3 and S1_C5_S2 planes.

Related literature

For related literature, see: Choi et al. (1988); Lin et al. (2005); Zhu et al. (1996, 1997).

S2. Experimental

To a suspension of 1-phenyl-butane-1,3-dione(21 mmol) and anhydrous K₂CO₃(60 mmol)in DMF(20 ml was added CS₂(30 mmol) at room temperature. After stirring for about 1 h, 1,2-dibromoethane (22 mmol) was added in full. Stirring was continued another 10 min at room temperature. Water(250 ml) was added to precipitate the yellow block-shaped product, which was recrystallized from ethanol, providing analytically pure compound suitable for single-crystal X-ray diffraction. M.p. 404 K°. Analysis: Found: C: 59.15, H: 4.50; calculated: C: 59.06, H: 4.58%. IR spectra: 3083,1647,1615,1418 and 1240 cm^{-1. 1}H-NMR: 2.08(3H,s,CH₃), 3.43(4H,m, 2*SCH₂), 7.70(5H,m, ph)

S3. Refinement

All H atoms were placed in calculated positions (C—H = 0.93 Å, 0.97 Å, 0.96Å of –CH, –CH₂ and-CH₃ respectively) and included in the refinement in the riding-model approximation with U_iso(H) = 1.2U_eq(carrier atom) (1.5U_eq for methyl H atoms).

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (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 atom labels and 30% probability displacement ellipsoids for non-H atoms.
	Fig. 2. The packing diagram of the compound. viewed down the c axis. H atoms have been omitted for clarity.

2-(1,3-Dithian-2-ylidene)-1-phenylbutane-1,3-dione

Crystal data

C13H12O2S2	F(000) = 276
Mr = 264.35	Dx = 1.436 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 3425 reflections
a = 7.812 (3) Å	θ = 2.7–27.8°
b = 5.5115 (18) Å	µ = 0.42 mm^−1
c = 14.628 (5) Å	T = 298 K
β = 103.876 (4)°	Block, yellow
V = 611.4 (4) Å^3	0.14 × 0.10 × 0.01 mm
Z = 2

Data collection

Bruker APEXII CCD diffractometer	1948 independent reflections
Radiation source: fine-focus sealed tube	1887 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.015
ω scans	θmax = 25.0°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −8→9
Tmin = 0.956, Tmax = 0.993	k = −6→6
3073 measured reflections	l = −17→17

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)] = 0.029	H-atom parameters constrained
wR(F^2) = 0.073	w = 1/[σ^2(Fo^2) + (0.0405P)^2 + 0.1246P] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max < 0.001
1948 reflections	Δρmax = 0.24 e Å^−3
154 parameters	Δρmin = −0.17 e Å^−3
1 restraint	Absolute structure: Flack (1983)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.01 (8)

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	0.45599 (7)	0.16653 (13)	0.16380 (4)	0.04320 (18)
S2	0.11323 (8)	0.39993 (14)	0.08953 (4)	0.04637 (18)
O1	0.4104 (2)	−0.2094 (4)	0.27828 (13)	0.0563 (5)
O2	−0.1208 (2)	0.2157 (4)	0.17817 (13)	0.0531 (5)
C1	0.2829 (3)	−0.1090 (5)	0.29623 (15)	0.0361 (5)
C2	0.1629 (3)	0.0454 (5)	0.22544 (15)	0.0342 (5)
C3	−0.0288 (3)	0.0456 (5)	0.21677 (16)	0.0377 (6)
C4	−0.1148 (3)	−0.1726 (6)	0.24704 (18)	0.0482 (7)
H4A	−0.2388	−0.1430	0.2380	0.072*
H4B	−0.0636	−0.2046	0.3124	0.072*
H4C	−0.0971	−0.3102	0.2101	0.072*
C5	0.2343 (3)	0.1860 (5)	0.16689 (14)	0.0348 (5)
C6	0.4601 (4)	0.4458 (6)	0.1000 (2)	0.0532 (7)
H6A	0.4788	0.5824	0.1431	0.064*
H6B	0.5552	0.4423	0.0679	0.064*
C7	0.2864 (4)	0.4705 (7)	0.0300 (2)	0.0614 (9)
H7A	0.2807	0.3597	−0.0222	0.074*
H7B	0.2720	0.6346	0.0055	0.074*
C8	0.2575 (3)	−0.1219 (5)	0.39431 (15)	0.0328 (5)
C9	0.3325 (3)	−0.3133 (5)	0.45259 (16)	0.0390 (5)
H9A	0.3892	−0.4378	0.4286	0.047*
C10	0.3233 (3)	−0.3194 (6)	0.54551 (17)	0.0459 (6)
H10A	0.3714	−0.4495	0.5836	0.055*
C11	0.2424 (3)	−0.1316 (6)	0.58230 (17)	0.0461 (7)
H11A	0.2390	−0.1337	0.6454	0.055*
C12	0.1671 (3)	0.0579 (6)	0.52532 (17)	0.0438 (6)
H12A	0.1111	0.1825	0.5497	0.053*
C13	0.1749 (3)	0.0631 (5)	0.43144 (16)	0.0368 (5)
H13A	0.1243	0.1917	0.3932	0.044*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0350 (3)	0.0536 (4)	0.0445 (3)	0.0025 (3)	0.0165 (2)	0.0021 (3)
S2	0.0403 (3)	0.0550 (4)	0.0434 (3)	0.0041 (3)	0.0093 (3)	0.0130 (3)
O1	0.0513 (11)	0.0737 (14)	0.0483 (10)	0.0252 (10)	0.0205 (8)	0.0065 (10)
O2	0.0350 (9)	0.0578 (14)	0.0650 (12)	0.0054 (9)	0.0091 (8)	0.0119 (10)
C1	0.0330 (11)	0.0399 (13)	0.0353 (12)	0.0004 (12)	0.0078 (9)	−0.0035 (12)
C2	0.0309 (11)	0.0423 (15)	0.0298 (11)	0.0007 (10)	0.0082 (9)	−0.0025 (11)
C3	0.0344 (12)	0.0467 (16)	0.0318 (11)	−0.0004 (11)	0.0073 (10)	−0.0018 (12)
C4	0.0393 (13)	0.059 (2)	0.0466 (14)	−0.0102 (12)	0.0099 (12)	0.0019 (13)
C5	0.0331 (11)	0.0413 (14)	0.0294 (10)	−0.0005 (11)	0.0066 (9)	−0.0056 (11)
C6	0.0499 (15)	0.058 (2)	0.0607 (16)	−0.0052 (13)	0.0302 (13)	−0.0006 (15)
C7	0.0612 (17)	0.077 (2)	0.0520 (16)	0.0039 (16)	0.0259 (14)	0.0197 (16)
C8	0.0279 (10)	0.0354 (13)	0.0341 (11)	−0.0003 (10)	0.0052 (8)	0.0013 (11)
C9	0.0346 (11)	0.0368 (14)	0.0460 (13)	0.0028 (12)	0.0103 (10)	0.0009 (12)
C10	0.0345 (11)	0.0525 (16)	0.0487 (13)	0.0018 (13)	0.0062 (10)	0.0188 (15)
C11	0.0402 (12)	0.0626 (19)	0.0346 (12)	−0.0066 (14)	0.0071 (10)	0.0035 (14)
C12	0.0490 (14)	0.0475 (16)	0.0358 (13)	0.0020 (12)	0.0117 (11)	−0.0068 (12)
C13	0.0384 (12)	0.0347 (13)	0.0352 (12)	0.0033 (10)	0.0050 (10)	0.0007 (10)

Geometric parameters (Å, º)

S1—C5	1.746 (2)	C6—H6A	0.9700
S1—C6	1.804 (3)	C6—H6B	0.9700
S2—C5	1.747 (3)	C7—H7A	0.9700
S2—C7	1.817 (3)	C7—H7B	0.9700
O1—C1	1.221 (3)	C8—C13	1.385 (3)
O2—C3	1.233 (3)	C8—C9	1.394 (3)
C1—C2	1.487 (3)	C9—C10	1.378 (3)
C1—C8	1.496 (3)	C9—H9A	0.9300
C2—C5	1.369 (3)	C10—C11	1.387 (4)
C2—C3	1.472 (3)	C10—H10A	0.9300
C3—C4	1.495 (4)	C11—C12	1.377 (4)
C4—H4A	0.9600	C11—H11A	0.9300
C4—H4B	0.9600	C12—C13	1.389 (3)
C4—H4C	0.9600	C12—H12A	0.9300
C6—C7	1.497 (4)	C13—H13A	0.9300
C5—S1—C6	95.83 (12)	H6A—C6—H6B	108.5
C5—S2—C7	96.03 (13)	C6—C7—S2	108.04 (19)
O1—C1—C2	121.3 (2)	C6—C7—H7A	110.1
O1—C1—C8	119.2 (2)	S2—C7—H7A	110.1
C2—C1—C8	119.2 (2)	C6—C7—H7B	110.1
C5—C2—C3	120.3 (2)	S2—C7—H7B	110.1
C5—C2—C1	118.4 (2)	H7A—C7—H7B	108.4
C3—C2—C1	121.3 (2)	C13—C8—C9	119.0 (2)
O2—C3—C2	120.6 (2)	C13—C8—C1	121.5 (2)
O2—C3—C4	119.5 (2)	C9—C8—C1	119.3 (2)
C2—C3—C4	119.6 (2)	C10—C9—C8	120.5 (2)
C3—C4—H4A	109.5	C10—C9—H9A	119.7
C3—C4—H4B	109.5	C8—C9—H9A	119.7
H4A—C4—H4B	109.5	C9—C10—C11	120.1 (3)
C3—C4—H4C	109.5	C9—C10—H10A	120.0
H4A—C4—H4C	109.5	C11—C10—H10A	120.0
H4B—C4—H4C	109.5	C12—C11—C10	120.0 (2)
C2—C5—S1	122.47 (19)	C12—C11—H11A	120.0
C2—C5—S2	123.26 (17)	C10—C11—H11A	120.0
S1—C5—S2	114.27 (14)	C11—C12—C13	120.0 (3)
C7—C6—S1	107.8 (2)	C11—C12—H12A	120.0
C7—C6—H6A	110.1	C13—C12—H12A	120.0
S1—C6—H6A	110.1	C8—C13—C12	120.5 (2)
C7—C6—H6B	110.1	C8—C13—H13A	119.8
S1—C6—H6B	110.1	C12—C13—H13A	119.8
O1—C1—C2—C5	−36.8 (4)	C5—S1—C6—C7	−36.6 (2)
C8—C1—C2—C5	137.1 (2)	S1—C6—C7—S2	45.7 (3)
O1—C1—C2—C3	142.2 (3)	C5—S2—C7—C6	−32.4 (3)
C8—C1—C2—C3	−43.9 (3)	O1—C1—C8—C13	149.8 (3)
C5—C2—C3—O2	−21.0 (4)	C2—C1—C8—C13	−24.2 (3)
C1—C2—C3—O2	160.0 (2)	O1—C1—C8—C9	−24.3 (4)
C5—C2—C3—C4	153.3 (2)	C2—C1—C8—C9	161.7 (2)
C1—C2—C3—C4	−25.7 (3)	C13—C8—C9—C10	0.6 (3)
C3—C2—C5—S1	−172.03 (19)	C1—C8—C9—C10	174.8 (2)
C1—C2—C5—S1	7.0 (3)	C8—C9—C10—C11	−1.4 (4)
C3—C2—C5—S2	8.2 (3)	C9—C10—C11—C12	1.7 (4)
C1—C2—C5—S2	−172.79 (18)	C10—C11—C12—C13	−1.1 (4)
C6—S1—C5—C2	−165.4 (2)	C9—C8—C13—C12	0.0 (3)
C6—S1—C5—S2	14.38 (17)	C1—C8—C13—C12	−174.0 (2)
C7—S2—C5—C2	−172.7 (2)	C11—C12—C13—C8	0.2 (4)
C7—S2—C5—S1	7.48 (18)