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

Abstract

The title compound, C2H6OS, 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 center dot center dot center dot C axis], with a C-S-C bond angle of 97.73 (7)degrees and an S-O bond length of 1.5040 (10) angstrom, corresponding very well with an S=O double bond, and with almost equal S-C bond lengths [mean value = 1.783 (4)angstrom] and O-S-C bond angles [mean value = 106.57 (4)degrees]. The crystal packing is influenced by CH-O interactions (2.42- 2.47 angstrom) 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 omega and the distance d(norm) 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 dnorm is the distance of the interacting atom from the plane perpendicular to the S=O bond.