Determination of Kinetic Parameters and Formation Constants of In(III)-{3-Hydroxy-3-o-Tolyl-1-(p-Carboxy-phenyl) Triazene} (HOTCPT) and In(III)-{3-Hydroxy-3-Ethyl-1-(p-Carboxyphenyl) Triazene} (HECPT) Complexes&

Abstract

The interaction of In³⁺ with hydroxy triazene has been studied at
dropping mercury electrode at a constant ionic strength. The reductions
were diffusion controlled but quasi-reversible. The E^r_1/2 have been obtained
by Gelling's method and the formation constants of the complexes
formed have been evaluated by Deford and Hume's method.
In(iii) forms four complex species with 3-hydroxy-3-o-tolyl-1-(p-carboxyphenyl)
triazene (HOTCPT) and 3-hydroxy-
3-ethyl-1-(p-carboxyphenyl) triazene} (HECPT) ions having β₁ =
5.5 X 10¹²,   β₂ = 7.1 X 10¹³,  β₃ = 50 X 10¹⁴,  β₄ = 384 X 10¹⁴ and
β₁= 1.2 x 10¹²,  β₂ = 4 X 10¹³,   β₃ = 112 X 10¹⁵,  β₄ = 8.8 x 10¹⁸.respec_
tively. The kinetic parameters have been calculated by Meites and Israel
method. The value of K_s comes of the order of 10₄ cm sec ^-1 confirming
the quasi-reversible nature of the electrode process. With increase in
complexing agent concentration, the value of K_s slightly decreases indicating
the increase irreversibility of the electrode process.