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4699778 
Journal Article 
Elucidation of the liquid-liquid distribution behavior of ion associates of metal-halogeno complex anions with quaternary ammonium counter cations and its application to separation and analysis 
Yamamoto, K; Motomizu, S 
2001 
1 
Bunseki Kagaku / Analysis Chemistry
ISSN: 0525-1931 
50 
1 
31-46 
WOS:000166626900002 
The distribution behavior of ion associates of both monovalent and divalent metal-halogeno complex anions with various quaternary ammonium cations between the aqueous phase and several organic phases {1,2-dichloroethane, chloroform (CF), chlorobenrene (Cl-B), benzene (B), toluene (T) and carbon tetrachloride (CTC)} was examined, and the extraction constants (log K-ex) were determined. The larger is the size of the ligand (Cl- < Br- < I-) and the coordination number, the greater is the ion associability. For the same coordination number, in general, the larger is the size of the metal ion, the greater is the ion associability. In general, the extractability of monovalent metal-halogeno complex anions is larger than that of divalent metal-halogeno complex anions. A linear relationship was obtained between log K-ex and the number of carbon atoms in quaternary ammonium ion, and the contribution of a methylene group to the extraction constant (Delta log k(ex)/-CH2-) was found to be about 0.4 similar to 0.8, Among the ion associates examined, the order of the extractability of the extracting solvent was generally CTC < T < B < Cl-B < CF. Also, the order of the extractability of the ion associates for dihalogenocuprate(I), tetrahalogenoaurate(III) and tetrahalogenothallate(III) complex ions was as follows, respectively: CuCl2- < CuBr2- < CuI2-; AuCl4- < AuBr4-; TlCI4- < TlBr4- < TlI4- The values of Delta log K-ex between the complex anions were almost equal, even though the extracting solvents were changed. From these results, several extraction-spectrophotometric methods for the determination of metal based on the formation of an ion associate of metal-halogeno complex anion with hydrophobic cations were developed. 
liquid-liquid distribution; metal-halogeno complex anion; quaternary ammonium ion; ion association; solvent extraction