Dimethyl-sulphoxide and its roles in the coordination chemistry of the uranyl ion

Structure determinations for the dimethyl-sulphoxide (DMSO) solvates of uranyl triflate, nitrate, picrate and a tetra-nuclear basic acetate show DMSO to be bound in all cases as an O-donor ligand but with the sulphur atoms involved in a variety of close approaches which may be significant in determining details of the complex ion structures. These close approaches, which generally mean that S may be considered to have '3+2' coordination, usually involve O of an adjacent DMSO or oxy-anion ligand, but can also involve uranyl-O and can be both intra- and inter-molecular. (authors)