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|Title:||Polarographic and potentiometric studies on some binary and ternary complex systems of dioxouranium(VI)|
Nair, M Sivasankaran
|Abstract:||The relative coordinating abilities of donor sites in the potentially tridentate ligands viz., asparagine. glutamine, aspartic acid and glutamic acid towards uranyl ion have been invgestigated by polarographic and pH-metric techniques. The metal ion forms 1:2 complexes under polarographic conditions. However, only 1:1 complex is observed under pH-metric conditions, where 1:2 complexes do not proceed due to extensive hydrolysis of the metal ion. The relative variations of E1/2 with pH and ligand concentration supported by conductometric titration.data indicate that the primary amino groups in the amino acids are not involved in coordination with uranyl ion. Further, the amide groups in asparagine and glutamine also do not participate in coordination thus rendering these ligands unidentate, In aspartic and glutamic acid complexes, seven- and eight- membered chelate rings are formed involving two terminal carboxyl groups. The mixed ligand complex equilibria of uranyl ion involving aspartic acid/glutamic acid as primary ligands (A) and maleic acid, malonic acid, succinic acid and lactic acid as secondary ligands (B) have also been studied by computer based numerical evaluation of pH titration data. The concentration profiles have indicated the favourability of the formation of ternary complexes in general as reflected in the logK values.|
|Appears in Collections:||IJC-A Vol.34A(03) [March 1995]|
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