Comparison of the C-H⋯O bonding in two crystalline phases of 1,4-di-thiane 1,1,4,4-tetra-oxide

• Published in: Acta crystallographica. Section E, Crystallographic communications Vol. 75; no. Pt 5; pp. 576 - 579
• Main Authors: Harlow, Richard L, Oliver, Allen G, Baker, Jonathan M, Marshall, William J, Sammes, Michael P
• Format: Journal Article
• Language: English
• Published: England International Union of Crystallography 01-05-2019
• Subjects: Research Communications; C—H⋯O bonding; crystal structures; 1,4-di­thiane-1,1,4,4-tetra­oxide
• ISSN: 2056-9890; 2056-9890
• DOI: 10.1107/S2056989019004407

The crystal structures of two crystalline phases of 1,4-di-thiane 1,1,4,4-tetra-oxide, C
H
O
S
, have been determined in order to examine the nature of possible inter-molecular hydrogen bonds. Phase 1 is monoclinic, space group
2/
, with unit-cell dimensions of
= 9.073 (8),
= 7.077 (6),
= 5.597 (5) Å and β = 105.89 (1)°. The mol-ecule adopts 2/
symmetry and all of the mol-ecules are related by translation and thus have the same orientation. Phase 2 is also monoclinic but in space group
2
/
with unit-cell dimensions of
= 7.1305 (5),
= 5.7245 (4),
= 8.3760 (6) Å and β = 91.138 (2)°. In this phase, the mol-ecule sits on an inversion center and the mol-ecules within the unit cell adopt quite different orientations. In both phases, examination of the potential C-H⋯O hydrogen bonds around each of the independent oxygen atoms (one axial and the other equatorial) shows the general O⋯H patterns to be quite similar with each oxygen atom in contact with four neighboring H atoms, and each H atom contacting two neighboring O atoms. While none of the H⋯O contacts is particularly short (all are greater than 2.5 Å), each mol-ecule has 32 such contacts that form an extensive inter-molecular network. A
H NMR spectrum of the compound dissolved in DMSO shows a singlet of 8H at δ 3.677 which indicates that the C-H bonds are only moderately polarized by the single adjacent -SO
- moiety: strongly polarized C-H bonds have δ values in the 5-6 range [Li & Sammes (1983 ▸).
, pp. 1303-1309]. The phase 1 crystal studied was non-merohedrally twinned.