Abstract
Hydrothermal reactions of different lanthanide(III) salts with (H~2~O~3~PCH~2~)~2~NCH~2~COOH (H~5~L^1^) led to two new layeredlanthanide(III) carboxylate‐diphosphonates, namely La(H~2~L^1^)(H~2~O)~2~·H~2~O (1) and La(H~2~L^1^)(H~2~O) (2). The structure of compound 1 features a layered architecture in which the nine‐coordinate La^3+^ ions are bridged by phosphonate groups of the ligands. The carboxylate group of the phosphonate ligand remains protonated and is involved in the interlayer hydrogen bonding. Compound 2 features a double layer structure in which the La^3+^ ion is eight‐coordinated and the carboxylate group of the ligand is chelated to a La^3+^ ion in a bidentate fashion. Hydrothermal reactions of lanthanide(III) salts with 4‐HOOC–C~6~H~4~–CH~2~N(CH~2~PO~3~H~2~)~2~ (H~5~L^2^) afforded three new compounds, namely, La(H~4~L^2^)(H~3~L^2^)(H~2~O)·2H~2~O (3), Er(H~3~L^2^)(H~4~L^2^) (4), and Er(HL^3^)(H~2~L^3^)(H~2~O) (5) [H~2~L^3^ = H~2~O~3~PCH~2~N(CHO)(CH~2~–C~6~H~4~–COOH)]. H~2~L^3^ was formed by the in situ oxidation of one P–C bond of the H~5~L^2^ ligand. Compound 3 features a (002) lanthanum(III) phosphonate layer in which the seven‐coordinate La^3+^ ions are bridged by diphosphonate moieties of the ligands. The carboxylate group remains protonated and is involved in the interlayer hydrogen bonding. The structure of compound 4 contains a 1D chain along the a axis in which each pair of ErO~6~ octahedra is bridged by a pair of phosphonate groups. These 1D chains are further interconnected by hydrogen bonds between noncoordinated phosphonate oxygen atoms into a (002) layer with the phenyl carboxylate groups hanging on the interlayer space. The structure of compound 5 is also layered. The interconnection of Er^3+^ ions by bidentate and tetradentate bridging phosphonate groups resulted in a (002) inorganic layer with the organic groups orientated to the interlayer space. Luminescence properties of compounds 4 and 5 have also been studied.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)