Structural parameters of dimethyl sulfoxide, DMSO, at 100 K, based on a redetermination by use of high-quality single-crystal X-ray data

The title compound, C(2)H(6)OS, is a high melting, polar and aprotic solvent widely used in organic and inorganic chemistry. It serves as a H-atom acceptor in hydrogen bonding and is used as an ambidentate ligand in coordination chemistry. The evaluation of the influence of inter­molecular inter­actions on the inter­nal structural parameters of the chemically bonded DMSO mol­ecules affords precise structural data of the free mol­ecule as a point of reference. So far, valid data have been obtained only by use of neutron powder diffraction [Ibberson (2005 ▸). Acta Cryst. C61, o571–o573]. In the present redetermination, structural data have been obtained from a single-crystal X-ray diffraction experiment at 100 K, revealing a better comparison with DMSO mol­ecules in other crystal structures. In the solid state, the pyramidal mol­ecule exhibits a nearly perfect C (s) symmetry [including H atoms, which are eclipsed with respect to the C⋯C axis], with a C—S—C bond angle of 97.73 (7)° and an S—O bond length of 1.5040 (10) Å, corresponding very well with an S=O double bond, and with almost equal S—C bond lengths [mean value = 1.783 (4) Å] and O—S—C bond angles [mean value = 106.57 (4)°]. The crystal packing is influenced by C—H⋯O inter­actions (2.42–2.47 Å) between all three H atoms of only one methyl group with the O atoms of three neighbouring DMSO mol­ecules. The inter­actions of the O atom with H atoms (or Lewis acids, or hydrogen-donor groups) of adjacent mol­ecules in relation to the orientation of the complete DMSO mol­ecule are described in terms of the angle ω and the distance d (norm); ω is the angle between the pseudo-mirror plane of the mol­ecule and the plane defined through the S=O bond and the inter­acting atom, and d (norm) is the distance of the inter­acting atom from the plane perpendicular to the S=O bond.