Syntheses, Characterizations, and Crystal Structures of Three New Metal Phosphonocarboxylates with a Layered and a Microporous Structure

Abstract

AbstractHydrothermal reactions of N‐(phosphonomethyl)proline (H3L) with MII (M = Cd, Pb, and Zn) chlorides resulted in three new metal amino‐phosphono‐carboxylates, namely, [Cd2LCl(H2O)] (1) and [Pb2Cl2(HL)] (2) with a layered structure, and [Zn7L6][Zn(H2O)6]2·16H2O (3) featuring a microporous structure built from centered octahedral Zn6(Zn) cluster anions. The cadmium(II) ions in complex 1 are octahedrally coordinated [Cd(1)O5Cl, Cd(2)O4NCl]. These cadmium octahedra form a 1D zigzag chain along the b‐axis through edge sharing, and such chains are further interconnected via phosphonate tetrahedra to form a <002> layer. The organic rings of the ligands are orientated to the interlayer space. Complex 2 also has a layered structure, in which Pb(1) is six‐coordinated by four phosphonate oxygen atoms and two carboxylate oxygen atoms from four ligands in a distorted octahedral geometry, three Pb−O distances are relatively longer than those of the remaining ones, whereas Pb(2) is six coordinated by three phosphonate oxygen atoms and one carboxylate oxygen from four ligands as well as two chloride anions in a distorted octahedral geometry, one Pb−O bond is much longer than the remaining ones. These two different types of PbII ions are further interconnected through bridging carboxylate and phosphonate groups to form a <200> layer. Complex 3 contains a novel heptanuclear zinc phosphonate cluster anion [Zn7L6]4− and two hexahydrated zinc(II) cations as well as 16 lattice water molecules. The seven ZnII cations in an anion form an unusual centered Zn6(Zn) octahedron, packing of such cluster anions creates micropores that are occupied by the hexahydrated zinc(II) cations and lattice water molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)