Synthesis and structural characterization of a calcium coordination polymer based on a μ3-bridging tetradentate binding mode of glycine

Abstract

A new coordination polymer namely [[Ca6(H-gly) 12(H2O)18]Cl12·6H 2O]n (1) (H-gly = glycine) has been isolated from the calcium chloride-glycine-water system and structurally characterized. Each Ca(II) in 1 is eight-coordinated and is bonded to eight oxygen atoms three of which are from terminal water molecules and five oxygen atoms from four symmetry related zwitterionic glycine ligands. The H-gly ligands exhibit two different binding modes viz. a monodentate carboxylate ligation and a μ3- tetradentate bridging carboxylate binding mode, which results in the formation of a one-dimensional coordination polymer. In the infinite chain the Ca(II) atoms are organized in a zigzag fashion. A comparative study reveals a rich and diverse structural chemistry of calcium halide-glycine compounds. © Indian Academy of Sciences.