title: Multinuclear complex formation in aqueous solutions of Ca(II) and heptagluconate ions.
abstract: The equilibria and structure of complexes formed between the Ca(2+) ion and the heptagluconate (Hglu(-)) ion in both neutral and alkaline solutions have been studied. In alkaline solutions an uncharged, multinuclear complex is formed with the composition of Ca3Hglu2(OH)4 (or [Ca3Hglu2H(-4)](0)) with an unexpectedly high stability constant (lg β(32-4) = 14.09). The formation of the trinuclear complex was deduced from potentiometry and confirmed by freezing-point depression measurements and conductometry as well. The binding sites of Hglu(-) were determined from NMR measurements. Besides the carboxylate group, the O atoms on the second and third carbon atoms proved to be the most probable sites for Ca(2+) binding.
authors: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, H-6720 Hungary.
authors: Attila
authors: A
authors: Pallagi
authors: Zita
authors: Z
authors: Csendes
authors: Bence
authors: B
authors: Kutus
authors: Eszter
authors: E
authors: Czeglédi
authors: Gábor
authors: G
authors: Peintler
authors: Péter
authors: P
authors: Forgo
authors: István
authors: I
authors: Pálinkó
authors: Pál
authors: P
authors: Sipos