Determination and comparison of the stability constants of some metal complexes of 8-hydroxyquinoline N-oxide and 8-hydroxyquinoline

1970 ◽  
Vol 23 (7) ◽  
pp. 1387 ◽  
Author(s):  
RD Gupta ◽  
GS Manku ◽  
AN Bhat ◽  
BD Jain
Keyword(s):  
Metal Complexes ◽  
Stability Constants ◽  
Sodium Perchlorate ◽  
Ionic Medium ◽  
The Stability ◽  
Gadolinium Break ◽  
Oxide Derivative

The stability constants of 8-hydroxyquinoline N-oxide (or "oxine N-oxide") complexes with MnII, Fell, CoII, Kill, CuII, ZnII, CdII, UO211, AlIII, FeIII, YIII, LaIII, CeIII, PrIII, NdIII, SmIII, GdIII, DyIII, HoIII, ErIII, TmIII, YbIII, and LuIII, and oxine complexes with LnIII and YIII have been determined using pH-metric titrations in 50% v/v aqueous dioxan in the presence of 0.30M sodium perchlorate as the constant ionic medium. With both the ligands, the "gadolinium break" is observed in the case of the lanthanon complexes, whereas the bivalent ion complexes follow the Irving-Williams order of stability constants in the case of the oxine complexes. The stability constants of the oxine complexes have been found to be larger than those of the N-oxide complexes, though the oxine anion is only five times as basic as the N-oxide anion. A possible explanation for the increased stability of the oxine complexes in comparison with the corresponding N-oxide derivative is proposed.

Stability constants and spectral studies of complexes of 2-hydroxy-5-methylazobenzene-2′-carboxylic acid with some divalent metal ions

1984 ◽  
Vol 62 (11) ◽  
pp. 2299-2301
Author(s):  
C. Mahalingam ◽  
J. K. Sthapak ◽  
D. D. Sharma ◽  
R. L. Tiwari ◽  
Smita Sthapak
Keyword(s):  
Carboxylic Acid ◽  
Metal Ions ◽  
Metal Complexes ◽  
Stability Constants ◽  
Divalent Metal ◽  
Reflectance Spectra ◽  
Spectral Studies ◽  
Divalent Metal Ions ◽  
The Stability

The stability constants of metal complexes of 2-hydroxy-5-methylazobenzene-2′-carboxylic acid have been determined spectrophotometrically. These follow the Irving–Williams sequence: log KOH(H) = 10.67, log K1(Co) = 9.02, log K1(Ni) = 9.68, log K1(Cu) = 13.37, log K1(Zn) = 7.58, and [Formula: see text]The chelates of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and [Formula: see text] with the dye have been prepared and characterized on the basis of their ir and reflectance spectra.

Potentiometric and thermodynamic studies of 3-methyl-1-phenyl-{p-[N-(pyrimidin-2-yl)-sulfamoyl]phenylazo}-2-pyrazolin-5-one and its metal complexes

2006 ◽  
Vol 60 (1) ◽  
Author(s):  
A. Fouda ◽  
A. Al-Sarawy ◽  
E. El-Katori
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Stability Constants ◽  
Dissociation Constants ◽  
Transition Metal Ions ◽  
Effect Of Temperature ◽  
Water Mixture ◽  
Dissociation Process ◽  
The Stability ◽  
Metal Ligand

AbstractThe dissociation constants of 3-methyl-1-phenyl-{p-[N-(pyrimidin-2-yl)sulfamoyl]phenylazo}-2-pyrazolin-5-one and metal-ligand stability constants of its complexes with some transition metal ions have been determined potentiometrically in 0.1 M-KCl and ethanol—water mixture (30 vol. %). The order of the stability constants of the formed complexes increases in the sequence Mn2+, Co2+, Ni2+, Cu2+, La3+, Hf3+, UO22+, Zr4+. The effect of temperature was studied and the corresponding thermodynamic parameters (ΔG, ΔH, and ΔS) were derived and discussed. The dissociation process is nonspontaneous, endothermic, and entropically unfavourable. The formation of the metal complexes was found to be spontaneous, exothermic, and entropically favourable.

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