Lanthanide coordination polymers with dicarboxylate-like ligands: crystal structures of polymeric lanthanum(III) and terbium(III) complexes with flexible double betaines

Abstract

Four novel polymeric lanthanide(III) complexes of two new double betaine derivatives have been synthesized and structurally determined. In [{La 2(L 1) 2(H 2O) 9} n ]Cl 6 n ·2 nH 2O ( 1) and [{Tb(L 1)(H 2O) 4} n ]Cl 3 n · nH 2O ( 2) (L 1=4,4′-trimethylenedipyridinio- N, N′-diacetate), the lanthanide(III) ions form a two-dimensional layer in which each pair of lanthanide(III) ions is bridged by two syn–anti μ-carboxylato- O, O′ groups. Adjacent layers are cross-linked through hydrogen bonds among aqua ligands, lattice water molecules and chloride ions, to form a three-dimensional network. Isomorphous [{Ln(L 2)(H 2O) 4} n ]Cl 3 n ·5 nH 2O (Ln=La, 3; Ln=Tb, 4; L 2=1,3 bis(pyridinio-4-carboxylato)-propane) each contain a centrosymmetric paddle-wheel-like dimeric unit in which each pair of adjacent metal atoms is bridged by four syn–syn μ-carboxylato- O, O′ groups that are oriented nearly perpendicular to each other about the metal–metal axis. Neighboring dimeric subunits are bridged by a pair of flexible L 2 ligands into a polymeric chain. Adjacent chains are inter-linked by hydrogen bonds among aqua ligands, lattice water molecules and chloride ions into a three-dimensional network.