The Crystal Structures of Two Novel Cadmium-Picolinic Acid Complexes in Relation to the Solution Species

Abstract

The crystal structures of two novel cadmium-picolinic acid complexes grown in aqueous solutions at selected pH values are reported. The structures are compared to expected solution species under the same conditions. The crystal structure of complex 1 exhibits a seven coordinate structure which contains a protonated picolinic acid ligand that bonds bidentately to the cadmium ion via both carboxylate oxygens. Two nitrates coordinate to the metal centre within the same plane, one monodentately and the other bidentately, and two water molecules are found in the axial positions. The structure of complex 2 shows cadmium bonded to three of N,O-bidentate picolinic acid ligands to produce a distorted octahedron.

Keywords: Cadmium, picolinic acid, solution species, crystal structures, controlled pH

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