(Z)-4,5-Di­bromo-3,3,6,6-tetra­methyl-2,3,6,7-tetra­hydro­thiepine-1,1-dione

The crystal of the title compound is formed from layers built from centrosymmetric pairs of mol­ecules. The mol­ecule adopts a twist conformation with the carbons next to sulfur above or below the mean plane.

Abstract

The crystal of the title compound, C₁₀H₁₆Br₂O₂S, is formed from layers built from centrosymmetric pairs of mol­ecules. The mol­ecule adopts a twist conformation with the carbon atoms next to sulfur above or below the mean plane.

Structure description

As part of our studies on the reactivity of angle-strained compounds (Krämer et al., 2009 ▸; Detert 2011 ▸), the addition of bromine appeared to be a challenging project (Chiappe et al., 2002 ▸; Detert et al. 1992 ▸). Whereas the addition of bromine to alkynes generally leads via bridged bromo­nium ions to trans-di­bromo­alkenes, the bromination of cyclo­octyne gives cis-1,2-di­bromo­cyclo­octene (Wittig & Dorsch, 1968 ▸). While this can proceed via isomerization of the initially formed trans isomer, the addition of bromine to cyclo­heptynes avoids cationic inter­mediates (Herges et al. 2005 ▸). The title compound (Fig. 1 ▸) was obtained within these studies via addition of bromine to tetra­methyl­thia­cyclo­heptyne-S,S-dioxide (Krebs et al. 1979 ▸). Two identical, non-symmetrical mol­ecules comprise the unit cell. The conformation of the seven-membered ring is similar to a twist form. The atoms C7,C1,C3,S5 are nearly coplanar with the largest deviation from planarity at C1 [0.056 (3) Å]. The atoms vicinal to sulfur adopt positions below [−0.789 (3) Å, C4] and above [0.785 (3) Å, C6] this plane. The tetra­substituted olefin is twisted, torsion angle C7—C1—C2—C3 is −13.7 (6)° and Br1—C1—C2—Br2 at −15.3 (3)° is even larger. Two mol­ecules are connected by a center of inversion, the packing appears as a layer structure (Fig. 2 ▸). Layers are parallel to the a axis, the minimal distance between bromine atoms (Br1⋯Br1′) of different layers is 3.4168 (6) Å.

Figure 1.

View of the title compound. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2.

Partial packing diagram. View along the a-axis.

Synthesis and crystallization

The title compound C₁₀H₁₆O₂Br₂S was prepared from the cyclic alkyne (Krebs et al., 1979 ▸; Krebs & Colberg 1980 ▸) by addition of bromine at 203 K according to the procedure given by Herges et al. (2005 ▸). After evaporation of the solvent, the oily compound crystallized after standing for 15 years at ambient temperature.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1 ▸.

Table 1. Experimental details.

Crystal data
Chemical formula	C10H16Br2O2S
M r	360.11
Crystal system, space group	Triclinic, P
Temperature (K)	193
a, b, c (Å)	5.9685 (4), 8.9642 (6), 12.4927 (9)
α, β, γ (°)	94.804 (6), 102.448 (5), 99.356 (5)
V (Å3)	639.09 (8)
Z	2
Radiation type	Mo Kα
μ (mm−1)	6.49
Crystal size (mm)	0.67 × 0.39 × 0.08
Data collection
Diffractometer	Stoe IPDS 2T
Absorption correction	Integration (X-RED; Stoe et al., 2019 ▸)
T min, T max	0.088, 0.553
No. of measured, independent and observed [I > 2σ(I)] reflections	8129, 3038, 2686
R int	0.023
(sin θ/λ)max (Å−1)	0.663
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.036, 0.089, 1.14
No. of reflections	3038
No. of parameters	140
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	1.28, −0.89

Computer programs: X-AREA WinXpose, Recipe and Integrate (Stoe & Cie, 2019 ▸), SHELXT2014 (Sheldrick, 2015a ▸), SHELXL2018/3 (Sheldrick, 2015b ▸) and PLATON (Spek, 2020 ▸).

Supplementary Material

CCDC reference: 2236694

Additional supporting information: crystallographic information; 3D view; checkCIF report

full crystallographic data

Crystal data

C10H16Br2O2S	Z = 2
Mr = 360.11	F(000) = 356
Triclinic, P1	Dx = 1.871 Mg m−3
a = 5.9685 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.9642 (6) Å	Cell parameters from 18448 reflections
c = 12.4927 (9) Å	θ = 2.7–28.4°
α = 94.804 (6)°	µ = 6.49 mm−1
β = 102.448 (5)°	T = 193 K
γ = 99.356 (5)°	Plate, colourless
V = 639.09 (8) Å3	0.67 × 0.39 × 0.08 mm

Data collection

Stoe IPDS 2T diffractometer	3038 independent reflections
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus	2686 reflections with I > 2σ(I)
Detector resolution: 6.67 pixels mm-1	Rint = 0.023
rotation method, ω scans	θmax = 28.1°, θmin = 2.7°
Absorption correction: integration (XRED; Stoe et al., 2019)	h = −7→7
Tmin = 0.088, Tmax = 0.553	k = −11→11
8129 measured reflections	l = −16→16

Refinement

Refinement on F2	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.036	H-atom parameters constrained
wR(F2) = 0.089	w = 1/[σ2(Fo2) + (0.0307P)2 + 1.4492P] where P = (Fo2 + 2Fc2)/3
S = 1.14	(Δ/σ)max < 0.001
3038 reflections	Δρmax = 1.28 e Å−3
140 parameters	Δρmin = −0.89 e Å−3
0 restraints

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Hydrogen atoms attached to carbons were placed at calculated positions and were refined in the riding-model approximation with C–H = 0.95 Å, and with Uiso(H) = 1.2 Ueq(C).

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

	x	y	z	Uiso*/Ueq
Br1	0.15368 (7)	0.46873 (4)	0.40230 (3)	0.03826 (12)
Br2	0.21628 (8)	0.13145 (5)	0.44057 (3)	0.04584 (13)
C1	0.2846 (5)	0.3563 (4)	0.3004 (2)	0.0251 (6)
C2	0.2791 (5)	0.2074 (4)	0.3085 (3)	0.0265 (6)
C3	0.3191 (6)	0.0802 (4)	0.2281 (3)	0.0281 (7)
C4	0.2643 (5)	0.1158 (4)	0.1074 (3)	0.0266 (6)
H4A	0.115877	0.154728	0.094409	0.032*
H4B	0.235588	0.018273	0.058883	0.032*
S5	0.46965 (15)	0.24522 (9)	0.06328 (7)	0.02945 (18)
C6	0.5605 (5)	0.3987 (3)	0.1695 (3)	0.0254 (6)
H6A	0.674923	0.368072	0.229620	0.031*
H6B	0.645465	0.484410	0.140356	0.031*
C7	0.3767 (5)	0.4610 (3)	0.2221 (3)	0.0226 (6)
C8	0.5636 (6)	0.0428 (5)	0.2667 (4)	0.0401 (9)
H8A	0.586667	−0.036909	0.213729	0.060*
H8B	0.578609	0.006994	0.339500	0.060*
H8C	0.681643	0.134537	0.271694	0.060*
C9	0.1385 (7)	−0.0676 (4)	0.2226 (4)	0.0396 (8)
H9A	0.155064	−0.144330	0.165629	0.059*
H9B	−0.019675	−0.045063	0.204374	0.059*
H9C	0.165983	−0.106587	0.294348	0.059*
O10	0.6724 (5)	0.1800 (3)	0.0569 (3)	0.0434 (7)
O11	0.3486 (5)	0.2945 (3)	−0.0361 (2)	0.0416 (6)
C12	0.1749 (6)	0.4981 (4)	0.1357 (3)	0.0300 (7)
H12A	0.238109	0.561693	0.085059	0.045*
H12B	0.078319	0.553061	0.172897	0.045*
H12C	0.079307	0.403256	0.093870	0.045*
C13	0.5228 (6)	0.6125 (4)	0.2895 (3)	0.0315 (7)
H13A	0.593338	0.675014	0.240333	0.047*
H13B	0.646160	0.589899	0.348092	0.047*
H13C	0.420881	0.668146	0.322457	0.047*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Br1	0.0480 (2)	0.0446 (2)	0.03061 (19)	0.01935 (16)	0.02005 (15)	0.00268 (15)
Br2	0.0666 (3)	0.0435 (2)	0.0296 (2)	0.00595 (19)	0.01546 (18)	0.01398 (16)
C1	0.0262 (14)	0.0332 (16)	0.0169 (13)	0.0094 (12)	0.0058 (11)	0.0003 (12)
C2	0.0254 (15)	0.0331 (16)	0.0230 (15)	0.0073 (12)	0.0064 (12)	0.0086 (13)
C3	0.0255 (15)	0.0251 (15)	0.0356 (18)	0.0066 (12)	0.0088 (13)	0.0062 (13)
C4	0.0242 (14)	0.0244 (15)	0.0296 (16)	0.0013 (12)	0.0075 (12)	−0.0034 (12)
S5	0.0316 (4)	0.0281 (4)	0.0289 (4)	−0.0004 (3)	0.0151 (3)	−0.0049 (3)
C6	0.0250 (14)	0.0226 (14)	0.0285 (16)	0.0033 (11)	0.0083 (12)	−0.0011 (12)
C7	0.0267 (14)	0.0217 (14)	0.0209 (14)	0.0066 (11)	0.0079 (11)	0.0008 (11)
C8	0.0314 (18)	0.0378 (19)	0.055 (2)	0.0150 (15)	0.0094 (16)	0.0136 (17)
C9	0.041 (2)	0.0278 (17)	0.052 (2)	0.0009 (15)	0.0191 (17)	0.0054 (16)
O10	0.0377 (14)	0.0372 (14)	0.0587 (18)	0.0019 (11)	0.0290 (13)	−0.0124 (12)
O11	0.0546 (16)	0.0428 (15)	0.0247 (12)	−0.0024 (12)	0.0133 (11)	0.0007 (11)
C12	0.0280 (16)	0.0327 (17)	0.0300 (17)	0.0070 (13)	0.0052 (13)	0.0087 (13)
C13	0.0373 (18)	0.0261 (16)	0.0291 (17)	0.0066 (13)	0.0053 (14)	−0.0034 (13)

Geometric parameters (Å, º)

Br1—C1	1.927 (3)	C6—H6B	0.9900
Br2—C2	1.923 (3)	C7—C12	1.536 (4)
C1—C2	1.343 (5)	C7—C13	1.556 (4)
C1—C7	1.536 (4)	C8—H8A	0.9800
C2—C3	1.538 (5)	C8—H8B	0.9800
C3—C8	1.535 (5)	C8—H8C	0.9800
C3—C4	1.543 (5)	C9—H9A	0.9800
C3—C9	1.552 (5)	C9—H9B	0.9800
C4—S5	1.758 (3)	C9—H9C	0.9800
C4—H4A	0.9900	C12—H12A	0.9800
C4—H4B	0.9900	C12—H12B	0.9800
S5—O11	1.438 (3)	C12—H12C	0.9800
S5—O10	1.441 (3)	C13—H13A	0.9800
S5—C6	1.758 (3)	C13—H13B	0.9800
C6—C7	1.547 (4)	C13—H13C	0.9800
C6—H6A	0.9900
C2—C1—C7	132.0 (3)	C1—C7—C12	111.0 (3)
C2—C1—Br1	117.5 (2)	C1—C7—C6	112.8 (2)
C7—C1—Br1	110.4 (2)	C12—C7—C6	112.6 (3)
C1—C2—C3	130.6 (3)	C1—C7—C13	109.7 (3)
C1—C2—Br2	118.0 (2)	C12—C7—C13	108.7 (3)
C3—C2—Br2	111.4 (2)	C6—C7—C13	101.5 (2)
C8—C3—C2	110.8 (3)	C3—C8—H8A	109.5
C8—C3—C4	113.7 (3)	C3—C8—H8B	109.5
C2—C3—C4	112.0 (3)	H8A—C8—H8B	109.5
C8—C3—C9	107.6 (3)	C3—C8—H8C	109.5
C2—C3—C9	110.2 (3)	H8A—C8—H8C	109.5
C4—C3—C9	102.1 (3)	H8B—C8—H8C	109.5
C3—C4—S5	119.1 (2)	C3—C9—H9A	109.5
C3—C4—H4A	107.5	C3—C9—H9B	109.5
S5—C4—H4A	107.5	H9A—C9—H9B	109.5
C3—C4—H4B	107.5	C3—C9—H9C	109.5
S5—C4—H4B	107.5	H9A—C9—H9C	109.5
H4A—C4—H4B	107.0	H9B—C9—H9C	109.5
O11—S5—O10	116.84 (18)	C7—C12—H12A	109.5
O11—S5—C4	107.11 (16)	C7—C12—H12B	109.5
O10—S5—C4	110.42 (17)	H12A—C12—H12B	109.5
O11—S5—C6	109.96 (16)	C7—C12—H12C	109.5
O10—S5—C6	106.90 (16)	H12A—C12—H12C	109.5
C4—S5—C6	105.01 (15)	H12B—C12—H12C	109.5
C7—C6—S5	119.5 (2)	C7—C13—H13A	109.5
C7—C6—H6A	107.4	C7—C13—H13B	109.5
S5—C6—H6A	107.4	H13A—C13—H13B	109.5
C7—C6—H6B	107.4	C7—C13—H13C	109.5
S5—C6—H6B	107.4	H13A—C13—H13C	109.5
H6A—C6—H6B	107.0	H13B—C13—H13C	109.5
C7—C1—C2—C3	−13.7 (6)	C3—C4—S5—O10	70.2 (3)
Br1—C1—C2—C3	165.7 (3)	C3—C4—S5—C6	−44.7 (3)
C7—C1—C2—Br2	165.3 (3)	O11—S5—C6—C7	71.3 (3)
Br1—C1—C2—Br2	−15.3 (3)	O10—S5—C6—C7	−161.0 (3)
C1—C2—C3—C8	102.4 (4)	C4—S5—C6—C7	−43.7 (3)
Br2—C2—C3—C8	−76.6 (3)	C2—C1—C7—C12	105.5 (4)
C1—C2—C3—C4	−25.7 (5)	Br1—C1—C7—C12	−73.9 (3)
Br2—C2—C3—C4	155.3 (2)	C2—C1—C7—C6	−21.9 (5)
C1—C2—C3—C9	−138.6 (4)	Br1—C1—C7—C6	158.6 (2)
Br2—C2—C3—C9	42.4 (3)	C2—C1—C7—C13	−134.3 (4)
C8—C3—C4—S5	−48.3 (4)	Br1—C1—C7—C13	46.3 (3)
C2—C3—C4—S5	78.3 (3)	S5—C6—C7—C1	74.8 (3)
C9—C3—C4—S5	−163.9 (2)	S5—C6—C7—C12	−51.8 (3)
C3—C4—S5—O11	−161.6 (2)	S5—C6—C7—C13	−167.8 (2)