The X-ray Structures of 2- and 3-Sulfolene and Two Halogenated Derivatives

Journal of Chemical Crystallography https://doi.org/10.1007/s10870-023-00982-4 ORIGINAL PAPER The X‑ray Structures of 2‑ and 3‑Sulfolene and Two Halogenated Derivatives R. Alan Aitken1 · Alexandra M. Z. Slawin1 · Dheirya K. Sonecha1 Received: 10 January 2023 / Accepted: 8 March 2023 © The Author(s) 2023, corrected publication 2023 Abstract The structures of the isomeric 2,5-dihydrothiophene 1,1-dioxide [orthorhombic, a = 11.340(2), b = 7.0887(15), c = 6.2811(13) Å, space group Pnma] and 2,3-dihydrothiophene 1,1-dioxide [orthorhombic, a = 6.3903(13), b = 7.2783(16), c = 11.075(2) Å, space group Pnma] have been determined and show perfectly planar rings with the expected bond lengths and angles. In contrast, the halogenated derivatives 3,3,4,4-tetrachlorotetrahydrothiophene 1,1-dioxide [monoclinic, a = 11.8716(8), b = 6.5579(4), c = 11.4802(8) Å, β = 97.705(17), space group P21/c] and 2,3-dibromotetrahydrothiophene 1,1-dioxide [orthorhombic, a = 5.2502(3), b = 11.3561(6), c = 24.9802(17) Å, space group Pbca] both show twisted conformations. The degree of planarity is compared with that in the structures of comparable 5-membered ring cyclic sulfones and C–H…O hydrogen bonding patterns are discussed for all four structures. Graphical Abstract The two isomeric sulfolenes are perfectly planar while tetrachloro- and dibromo-derivatives adopt twisted structures. Keywords Cyclic sulfones · X-ray structure · Conformation Introduction Some time ago we described the X-ray structures of a range of ten symmetrical and unsymmetrical sulfones [1]. Although these included diaryl, aryl alkyl and dialkyl sulfones they were all acyclic. In studies related to the thermal extrusion of SO2 from cyclic sulfones, we and others have recently reported structures for various cyclic sulfones (Fig. 1) [2–5]. A survey of the structural data for simple cyclic sulfones, particularly those containing a five-membered ring, led to the realisation that the structures of several * R. Alan Aitken 1 EaStCHEM School of Chemistry, University of St Andrews, St Andrews, Fife KY16 9ST, UK key compounds have not yet been determined. In this paper we report the crystal and molecular structures for 2,5-dihydrothiophene 1,1-dioxide (butadiene sulfone, 3-sulfolene) 1, its isomer 2,3-dihydrothiophene 1,1-dioxide (2-sulfolene) 2 and the halogenated derivatives 3,3,4,4-tetrachlorotetrahydrothiophene 1,1-dioxide 3 and 2,3-dibromotetrahydrothiophene 1,1-dioxide 4 (Scheme 1). Experimental Compound 1 was obtained commercially and converted into the isomer 2 by base-induced isomerisation using the published method [6]. Photochemical chlorination of 1 gave 3 [7, 8] while addition of bromine to 2 gave the trans-dibromide 4 13 Vol.:(0123456789) Journal of Chemical Crystallography Fig. 1  Some recently determined cyclic sulfone structures with CCDC Ref Codes, literature references and sum of in-ring torsion angles Br S Br O O O O H DEKXEW [2] 98.29º Cl Cl Cl Cl S O Cl2, hν S O 3 Ph Ph H O S O O S 2 S O O O DOXJAD [5] 123.41º UJEWIS [4] 157.24º aq KOH 1 O CH2iPr KIMDIW [3] 158.71º O S O O Br2 S Br 4 O O Br Scheme 1  Structures and synthetic routes for compounds 1–4 [9, 10]. All four compounds had melting points and spectroscopic data in agreement with published values. Data were collected on Rigaku XtalLAB P200 (1,2,4) or Rigaku SCX Mini (3) diffractometers using graphite monochromated Mo Kα radiation λ = 0.71075 Å and are summarised in Table 1. The data can be obtained free of charge from the Cambridge Crystallographic Data Centre via http://www.ccdc.cam.ac.uk/getstructures. The structures were solved by direct methods and refined by full-matrix least-squares against F2 (SHELXL, Version 2018/3 [11]). Results and Discussion The structures of 3-sulfolene 1 and 2-sulfolene 2 are shown in Fig. 2 and both are perfectly planar with equivalent oxygen atoms located equidistant above and below the plane containing the ring atoms. The bonds lengths and angles (Table 2) are as expected and in good agreement with those observed for acyclic sulfones [1] and the average bond lengths of 1.786 Å for C–S and 1.436 Å for S=O for sulfones in general [12]. The structure of 1 was in fact investigated at a very early stage (Ref Code ZZZGBM) [13], but the methods of that time only allowed some rough information on the unit cell dimensions to be obtained. There is a more recent structure determination, which for some reason is not included in the CSD, that gives a very similar result to ours (space group Pnma, a = 11.484, b = 7.262, c = 6.316Å) [14]. Whilst wishing to give full credit to this earlier determination, we feel it is important 13 to finally document the structure of this fundamental compound in the CSD. For comparison a range of simple analogues of 1 (Fig. 3) [15–22] and 2 (Fig. 4) [15, 23–26] that have been crystallographically characterised are shown with CSD reference codes, literature references and, as a measure of planarity, the sum of the five in-ring torsion angles. As compared to the structures of 1 and 2 which have all torsion angles zero, we can see that introducing a substituent has a range of effects on the degree of planarity from no effect (IPRNSO) to small (GAMKEK), moderate (BAHQEG, MIXYUN, XOJFUX, WASBOI) and fairly large (BAHQIK, VUFKIS, XUTVUF, VAGXAC). However the presence of a ring double bond in all these compounds limits the possible degree of non-planarity. As might be expected, coordination of the oxygen of 1 to M oCl5 results in significant lengthening of that S–O bond and movement of sulfur out of the plane of the ring carbons [22]. The structures of both 1 and 2 show a range of weak C–H…O hydrogen bonds and these are listed in Table 3. As shown in Fig. 5, the different position of the double bond between 1 and 2 leads to different higher level motifs with 1 forming R22(8) dimers while 2 displays R21(4) interactions. The structures of halogenated derivatives 3 and 4 are shown in Fig. 6 and, in contrast to those of 1 and 2, these are significantly twisted with C(3) 0.432 Å above and C(4) 0.261 Å below the plane defined by S(1), C(2) and C(5) in 3. In the case of 4 there is again a twisted conformation with C(3) 0.489 Å above and C(4) 0.249 Å below the plane defined by S(1), C(2) and C(5), although Journal of Chemical Crystallography Table 1  Summary of crystallographic data obtained for compounds 1–4 Compound 1 2 3 4 CCDC deposit no. Empirical formula Formula weight Crystal system Space group Temperature (K) Crystal form Size (mm) Unit cell Dimensions (Å, °) 2225717 C4H6O2S 118.15 Orthorhombic Pnma (No. 62) 93 Colourless prism 0.10 ⋅ 0.05 ⋅ 0.05 a = 11.340(2) b = 7.0887(15) c = 6.2811(13) 2225718 C4H6O2S 118.15 Orthorhombic Pnma (No. 62) 93 Colourless prism 0.10 ⋅ 0.05 ⋅ 0.05 a = 6.3903(13) b = 7.2783(16) c = 11.075(2) 2225720 C4H6Br2O2S 277.96 Orthorhombic Pbca (No. 61) 93 Colourless prism 0.12 ⋅ 0.03 ⋅ 0.03 a = 5.2502(3) b = 11.3561(6) c = 24.9802(1 (...truncated)