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South African Journal of Chemistry

versión On-line ISSN 1996-840X
versión impresa ISSN 0379-4350

S.Afr.j.chem. (Online) vol.64  Durban  2011




The crystal structures of two novel cadmium-picolinic acid complexes in relation to the solution species



Caren Billing*; Demetrius C. Levendis; Vanessa L. Vieira

Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, P.O. WITS, 2050, South Africa




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 thatbonds 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



Full text available only in pdf format.



The financial assistance of the National Research Foundation (NRF) towards this research is hereby acknowledged. Opinions expressed and conclusions arrived at are those of the author and are not attributed to the NRF. The authors also thank Dr M.A. Fernandes for assistance in data collection and advice.



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Received 23 March 2011
Revised 28 March 2011
Accepted 8 April 2011



Submitted by invitation to celebrate 2011 the 'International Year of Chemistry'
* To whom correspondence should be addressed. E-mail:

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