Preparation and crystal structures of two dimeric lanthanoid(III) complexes containing pyridinioacetate and 2,2'-bipyridine ligands: [Ln(2)(bpy)(2)(pybet)(4)(H2O)(4)](bpy)(3)(ClO4)(6)center dot H2O (Ln=Eu and Tb)

Two dimeric lanthanoid(III) complexes, [Ln(2)(bpy)(2)(pybet)(4)(H2O)(4)](bpy)(3)(ClO4)(6).H2O (bpy = 2,2'-bipyridine, pybet = pyridinioacetate, and Ln = Eu and Tb), have been prepared and characterized by X-ray crystallography. The complexes are isostructural, each comprising a quadruply carboxylato-bridged, centrosymmetrical dimeric cation, six perchlorate anions, three uncoordinated bpy molecules and a lattice water molecule. Each Ln ion is surrounded in a distorted square-antiprismatic environment by four carboxylato oxygen atoms, two nitrogen atoms of the bidentate bpy ligand and two aqua ligands. The Ln-O bond lengths range from 2.33 to 2.44 Angstrom, and Ln-N bond lengths from 2.55 to 2.64 Angstrom. The uncoordinated bpy molecules are linked to the aqua ligands by hydrogen bonds.