Structures of the hydrated La(III), Nd(III) and Er(III) methanesulfonates

Full text: The methanesulfonates of trivalent lanthanides, Ln(CH3SO3)3.2H2O (Ln = La, Nd and Er) have been prepared by the reaction of methanesulfonic acid with a suspension of the respective lanthanide oxides (Ln2O3) in water. Single crystals, suitable for X-ray examination, were obtained by slow evaporation of water/ethyl alcohol 1:1 solutions. The isostructural tris(methanesulfonate)dihydrates of trivalent Nd and Er crystallize in a monoclinic system, space group P21/c, with Z = 4, and cell parameters: a = 942.5(2); β = 1422.4(2); c 976.5(1) pm; b = 91.18(1)o for Nd; and a 922.4(7), b = 1394.8(9), c = 9.560(7) pm, β = 91.00(6)deg. The dihydrated lanthanum compound crystallizes in a triclinic system, space group P-1, with two molecules per elementary cell. Its crystallographic parameters are a = 524.7(4); b 1011.4(7); c = 1291. 2(6)pm; α 98.73(5)deg; β= 107.16(4)deg and γ = 104.55(8)deg. In all investigated compounds the methanesulfonate anion acts as a bidentate ligand, bridging two metallic centres to yield polymeric structures. The trivalent Nd and Er are octa coordinated, to six methanesulfonate anions and two water molecules, giving a distorted bicapped prism as coordination polyhedron. The La cation is eneacoordinated, with a very amazing structure. Six methanesulfonate anions are coordinated to the central cation as well as three water molecules. Two water molecules are coordinated as bidentate ligands bridging two La(III) ions with an angle of 129.9(2)deg, while the third one coordinates in a terminal form. The coordination polyhedron around the lanthanum cation is a distorted tricapped prism. The far infrared spectra of Ln(CH3SO3)3.2H2O (Ln = La, Nd and Er) were registered in a matrix of polyethylene in the range of 200 to 700 cm-1 and also classified the compounds into two isomorphous series which are coherent with the X-ray structural investigation