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A novel mixed-ligand complexes of Er(III), Yb(III) and Lu(III) with title ligands were prepared and characterized by chemical and elemental analysis and IR spectroscopy, conductivity (in methanol, dimethyloformamide and dimethylsulphoxide). The thermal properties of complexes in the solid state were studied. The mode of metal-ligand coordination was discussed. The title compounds are isomorphic and isostructural in solid state. All atoms in studied compounds lie in general positions but occurrence of inversion on the midpoint of the bond linking two pyridine rings leads to existence in asymmetric unit one complex molecule and half of outer coordination sphere 4-bpy molecule. All chelating carboxylate groups are symmetrically bonded to the metal cations. The molecules of studied compounds are connected to the three dimensional network via O-HÁÁÁO and O-HÁÁÁN intermolecular hydrogen bonds. In the structures also exist C-HÁÁÁO, C-HÁÁÁCl weak hydrogen bonds and pÁÁÁÁp stacking interactions.

New Y(III) and La(III) complexes with 4-bpy (4,4 0 -bipyridine) and trichloro-or dibromoacetates with the formulae: Y(4-bpy) 2 (CCl 3 COO) 3 ÁH 2 O I, La(4-bpy) 1.5 (CCl 3 COO) 3 Á2H 2 O II, Y(4-bpy) 1.5 (CHBr 2 COO) 3 Á3H 2 O III, and La(4-bpy)(CHBr 2 COO) 3 ÁH 2 O IV were prepared and characterized by chemical, elemental analysis, and IR spectroscopy. Conductivity studies (in methanol, dimethyloformamide, and dimethylsulfoxide) were also described. They are small, crystalline substances. The way of metalligand coordination was discussed. The thermal properties of complexes in the solid state were studied by TG-DTG techniques under dynamic flowing air atmosphere. TG-FTIR system was used to analyze principal volatile thermal decomposition and fragmentation products evolved during pyrolysis in dynamic flowing argon atmosphere for La(III) compounds.