Crystal structure of 1,6-dithiacyclodeca-cis-3,cis-8-diene (DTCDD)

The title compound, C8H12S2 (trivial name DTCDD), was obtained as a side product of the reaction between cis-1,4-dichlorobut-2-ene and sodium sulfide. The asymmetric unit consists of one-quarter of the molecule (S site symmetry 2) and the complete molecule has 2/m (C 2h) point symmetry with the C=C bond in an E conformation. The geometry of the title compound is compared to those of a chloro derivative and a mercury complex.


Related literature
The structure of the compound having the ethylinic H atoms replaced by Cl atoms has been reported (Eaton et al., 2002) as has one where the title compound is ligated to Hg atoms (Cheung & Sim, 1965 (Allen, 2002). Symmetry codes: (i) 1 À x, y, z; (ii) x, 1 À y, 1 À z.
The S1-C1 bond lengths in DTCDD and the Cl derivative are within 3σ of each other while the C1-C2 distance in the Hg complex is ~6σ greater than the other two. The two C2-C1-S1 angles in DTCDD and the Cl derivative differ by as much as 16σ; the same angle in the Cl derivative may differ by as much as 5σ (5°) from the Hg derivative, while the DTCDD and Hg derivative angles are essentially the same (≤3σ). A difference of as much as 8σ is noted between the C2═C2-C1 angles in DTCDD and the Cl derivative, while the Hg analog angle is within 3σ of both of the other compounds. Many of these differences may likely be attributed to the presence of the Cl's on all four C2's only in the Cl derivative.

S2. Synthesis and crystallization
DTCDD is a side product of the reaction of cis-1,4-dichloro-2-butene and sodium sulfide in MeOH/DMSO. DTCDD was slowly recrystallized from a solution in pentane to yield colourless parallelepipeds.

Figure 2
The unit-cell packing in DTCDD viewed down the b-axis.

1,6-Dithiacyclodeca-cis-3,cis-8-diene
where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.19 e Å −3 Δρ min = −0.22 e Å −3 Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor, wR, and goodness of fit, S, are based on F 2 , conventional R-factors, R, are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.