Structures of the anhydrous Yb(III) and the hydrated Ce(III), Sm(III) and Tb(III) methanesulfonates

The methanesulfonates of trivalent lanthanides, Ln(CH3SO3)(3) . xH(2)O (Ln=Ce, Sm and Tb with x=2 and Ln=Yb with x=0), have been prepared by the reaction of mechanesulfonic acid with the respective lanthanide oxide (CeO2, Sm2O3, Tb4O7 and Yb2O3) in the presence of water. In the reactions involving cerium and terbium oxides, hydrogen peroxide was used as reducing agent. Single crystals, suitable for X-ray examination, were obtained by slow evaporation of water-ethyl alcohol (50:50, v/v) solution. The isostructural tris(methanesulfonate)dihydrates of the trivalent Ce, Sm and Tb crystallize in the monoclinic system, space group P2(1)/c (14), with Z=4, and cell parameters: a=948.9(1); b=1431.9(2); c=983.7(1) pm, beta=91.22(2)degrees for Ce; a=938.1(1), b=1417.9(2), c=974.3(3) pm, beta=91.19(2)degrees for Sm; and a=931.3(3), b=1407.2(3), c=966.4(3) pm, beta=91.09(3)degrees for Tb. Also the water-free ytterbium compound crystallizes in the monoclinic system, however the space group is P2, (4), with two molecules per elementary cell. Its crystallographic parameters are a=979.8(5), b=509.4(2), c=1183.7(5) pm and beta=107.16(4)degrees. In all investigated compounds the methanesulfonate anion acts as a bidentate ligand, bridging two metallic centers to yield polymeric structures.