Electrode reactions of palladium(II) in chloride solution at carbon paste electrodes modified with derivatives of N-benzoylthiourea |
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Authors: | Karl-Heinz Lubert Markus Guttmann Lothar Beyer |
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Institution: | (1) Institute of Inorganic Chemistry, University of Leipzig, Johannisallee 29, 04103 Leipzig, Germany,;(2) Institute of Microstructure Technology, Forschungszentrum Karlsruhe GmbH, P.O.B. 3640, 76021 Karlsruhe, Germany, |
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Abstract: | The study of the electrode reactions of palladium(II) at non-modified carbon paste electrodes (CPEs) in chloride solution
has revealed the existence of a chloropalladate(II) complex at the electrode surface. The complex is formed during the application
of anodic potentials after preceding palladium deposition. In the present paper the electrode reactions of PdII at CPEs modified with some N′,N′-disubstituted derivatives of N-benzoylthiourea as selective ligands for palladium(II)] are studied in chloride solution by cyclic voltammetry. Two reduction
peaks are observed in the cathodic scans recorded after deposition of palladium and anodization of the electrode. From the
results it is concluded that in addition to the chloropalladate(II) complex, observed at the non-modified electrode] a second
palladium complex is formed at positive potentials. The formation of the palladium(II) complex of the N-benzoylthiourea derivatives by ligand exchange at the electrode surface is assumed. The ligand exchange itself occurs without
charge transfer across the electrode|solution interface; therefore, it cannot be detected electrochemically. After palladium
deposition and anodic treatment a pronounced "inverse" peak (i.e., an anodic peak in the cathodic scan) with peak currents
up to 100 μA is observed at about +0.8 V. Its peak current increases with the amount of deposited palladium and the number
of cycles. The reactions at the electrode surface are discussed. The results of the study reveal the existence of two different
surface complexes of palladium(II) at ligand-modified CPEs, but the surface reactions could not be elucidated in detail.
Electronic Publication |
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Keywords: | N-Benzoylthiourea Carbon paste electrode Chloride Palladium Surface complex |
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