Enhanced stability of ternary complexes in solution through the participation of heteroaromatic N bases. Comparison of the coordination tendency of pyridine, imidazole, ammonia, acetate, and hydrogen phosphate toward metal ion nitrilotriacetate complexes

1981 ◽  
Vol 20 (8) ◽  
pp. 2586-2590 ◽  
Author(s):  
Debabrata. Banerjea ◽  
Thomas A. Kaden ◽  
Helmut. Sigel
Keyword(s):  
Metal Ion ◽  
Ternary Complexes ◽  
Hydrogen Phosphate ◽  
Enhanced Stability

Ternary Complexes in Solution, XXX Increased Stability Through Intramolecular Stacking in Mixed-Ligand Cu 2+ and Zn 2+ Complexes of 2,2′ -Bipyridyl and Carboxymethyl Aryl Derivatives

1979 ◽  
Vol 34 (2) ◽  
pp. 208-216 ◽  
Author(s):  
Etelka Farkas ◽  
Beda E. Fischer ◽  
Rolf Griesser ◽  
Volker M. Rheinberger ◽  
Helmut Sigel
Keyword(s):  
Metal Ion ◽  
Ternary Systems ◽  
Ternary Complexes ◽  
Mixed Ligand ◽  
Difference Spectra ◽  
Ternary Metal ◽  
The Stability ◽  
Stability Enhancement ◽  
Aryl Sulfide ◽  
Enhanced Stability

Abstract The stability constants of ternary Cu 2+ and Zn 2+ complexes, each of which contains 2,2′-bipyridyl and a carboxymethyl aryl sulfide, were determined in 50% aqueous dioxane. A comparison of the stability of these ternary complexes with those formed with simple carboxylates demonstrates an enhanced stability of the carboxymethyl aryl sulfide containing mixed ligand complexes. This enhanced stability is not due to a thioether-metal ion interaction, but due to an intramolecular aromatic stacking interaction between the aryl moiety of the carboxymethyl aryl sulfide and 2,2′-bipyridyl. Indeed, by UV difference spectra and by PMR measurements it is possible to show that a binary (metal ion-free) stacked adduct between the aromatic moieties of the two mentioned ligands is formed. Furthermore, by studying the binary and ternary systems of Zn 2+ or Cu 2+ , 2,2′-bipyridyl and hydrocinnamate, i.e. 3-phenylpropionate (-S-of carboxymethyl phenyl sulfide is replaced by -CH2-), it becomes obvious that the thioether moiety is not essential for the observation of an enhanced stability of the ternary complexes. PMR shift studies of 2,2′-bipyridyl/Zn 2+ /carboxymethyl aryl sulfide systems confirm the presence of stacking in the corresponding ternary complexes. Depending on the kind of the ternary metal ion complex the stability enhancement, due to the intramolecular stacking between the aromatic parts of the coordinated ligands, is between about 0.2 to 0.5 log unit.

THERMODYNAMICS OF ALKALI AND ALKALINE EARTH METAL ION - EXCHANGE ON CERIUM(IV) HYDROGEN PHOSPHATE

1995 ◽  
Vol 13 (6) ◽  
pp. 1145-1158 ◽  
Author(s):  
H. Hayashi ◽  
T. Iwasaki ◽  
T. Nagase ◽  
Y. Onodera ◽  
K. Torii
Keyword(s):  
Ion Exchange ◽  
Metal Ion ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Alkaline Earth Metal ◽  
Hydrogen Phosphate ◽  
Metal Ion Exchange
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