Thallium(III) chloride in organic solvents: Synthesis, solutions and solvates. The crystal structures of trichlorobis(dimethylsulfoxide)thallium(III) and tribromobis(dimethylsulfoxide)thallium(III)

Abstract

The synthesis of thallium(III) chloride and bromide was performed in solution by chlorination and bromination, respectively, of the suspensions of the corresponding thallium(I) halides in acetonitrile. Crystalline compounds TlX 3(CH 3CN) 2 (X = Cl −, Br −) were prepared from the acetonitrile solutions. Thallium(III) chloride and bromide in dimethylsulfoxide solution were obtained by dissolving the corresponding solid compounds TlX 3(CH 3CN) 2 (Cl −, Br −) in DMSO. Both acetonitrile and dimethylsulfoxide solutions of thallium(III) chloride were studied by UV–Vis and 205Tl NMR spectroscopy. The UV–Vis study of the TlCl 3–CH 3CN system showed presence of at least two thallium(III) chloride species. Only one signal arising from the thallium(III) species was, however, detected by the 205Tl NMR in the solution because of the fast chemical exchange. The 205Tl NMR study of thallium(III) chloride in dimethylsulfoxide showed three separate signals assigned to the solvated TlCl 4 - , TlCl 3 and TlCl 2 + species. The crystalline compounds of trichlorobis(dimethylsulfoxide)thallium(III) and tribromobis(dimethylsulfoxide)thallium(III) were prepared and their crystal structures were solved by single-crystal X-ray analysis. The thallium atom in the complexes has a trigonal bipyramidal environment built by three halide ions occupying equatorial positions of the polyhedron and two oxygen atoms of the DMSO molecules in the apical positions.