Crystal Structure of 3-(1,3-Dithiolan-2-ylidene)pentane-2,4-dione

Abstract

In 1,1-diacetyl ethylenes, three conformations (EE, EZ and ZZ) must be taken into account. In 1,1-bis-methylthio-2,2-diacetyl ethylene and 1,1-bis-methylthio-2,2-dicarbomethoxy ethylene, the S-cis-S trans arrangement of the carbonyl groups with respect to the C-C double bond approximates the EZ conformation. However, in 3-bis(methylthio)methylene-pentane-2,4-dione, which is closely related to the title compound ( Fig. 1), it approximates the EE conformation. 3 The title compound was obtained by the reaction of acetyl acetone with carbon disulfide in the presence of a base, followed by alkylation with 1,2-dibromoethane.To a suspension of KOH (5.6 g, 0.1 mol) in acetonitrile (30 ml) a mixture of acetyl acetone (10 ml, 0.1 mol) and carbon disulfide (0.1 mol, 6.5 ml) was added and stirred for 2 h at room temperature. A solution of 1,2-dibromoethane (8.5 ml, 0.1 ml) in 10 ml acetonitrile was added to this, and stirred for another 24 h. The obtained crude solid was washed with water, evaporated in a vacuum and recrystallized from dichloromethane.Colorless prismatic crystals used for data collection were obtained by slow evaporation from an acetone solution. X-ray intensity data were collected on a Enraf-Nonius CAD-4 diffractometer with Cu Kα radiation (λ = 1.5418 Å) in the ω-2θ scan mode. Then, 868 reflections were measured (hmax = 0; kmax = 17; lmax = 9), of which 849 were treated while being observed with I > 2σ(I). Data were corrected for Lorentz, polarization and extinction effects.Crystal data, intensity collection conditions and refinement parameters are given in Table 1.The structure was solved by direct methods using SHELXS97. Isotropic refinements of the hydrogen atoms and anisotropic refinements of the non-hydrogen atoms lowered the R-factor to 0.0309. All hydrogen atoms were fixed by the program. The absolute structure of this crystal was determined by Flack's parameters-0.02(3). The maximum and minimum electron densities in the final difference Fourier map were at 0.49 e Å -3 x221 ANALYTICAL SCIENCES 2007, VOL. 23 X-ray Structure Analysis OnlineCrystal Structure of 3-(1,3-Dithiolan-2-ylidene)pentane-2,4-dione Kerala, India This compound with molecular formula C8H10O2S2 crystallized in the orthorhombic space group Pca21 (Z = 4) with unitcell parameters a = 7.3576(9)Å, b = 14.2238(11)Å, c = 8.714(2)Å. The structure was solved by direct methods and refined to R = 0.0309. This compound approximates the rare ZZ conformation in which both the ketenedithioacetal group and the oxygen atoms are on the same plane with the sulfur atoms close to the respective oxygen atoms.

Annulation of a 1,3-dithiole ring to a sterically hindered o-quinone core. Novel ditopic redox-active ligands

“…The S(1)–O(2) distance (Figure S4 in Supporting Information File 1 ) is 2.560(2) Å, it is less than the sum of the van der Waals radii. A very similar geometry was previously observed in the case of the acetylacetonate unit attached to a 1,3-dithiole ring [ 31 ].…”

“…The S(1)-O(2) distance (Figure S4 in Supporting Information File 1) is 2.560(2) Å, it is less than the sum of the van der Waals radii. A very similar ge- ometry was previously observed in the case of the acetylacetonate unit attached to a 1,3-dithiole ring [31]. o-Quinone 7, which is the minor product in the reaction of 4 with acetylacetone gem-dithiolate, is particularly interesting since information on the geometrical configuration of the benzothiete molecule is scarce and, to the best of our knowledge, this is the first example of a structurally characterized benzothiete species.…”

Crystal and Molecular Structure of 1,1-Bis(methylthio)-5-(4-chlorophenyl)-1,4-pentadien-3-one

“…The bond lengths and bond angles for the nonhydrogen atoms are listed in Tables 2 and 3, respectively. The structure is more planar compared to our earlier reported structures having a dithiolane ring [6][7][8][9][10].…”

“…The atoms C2, S1, and O1 are having deviations 0.226Å, The presence of the bis(methylthio) group as a donor and the cinnamoyl moiety as an acceptor about the double bond C10-C11 was expected to induce a "weak" pushpull character. The C10-C11 bond length [1.360(5)Å] is less than the corresponding average length [1.388Å] found in structures having a dithiolane ring attached to C(10) carbon [6][7][8][9][10]. The angle S1-C11-S2 [115.8(2) ∘ ] is greater than the corresponding angle [113.8 ∘ ] in the dithiolane ring of these compounds.…”