Formation Constants and Thermodynamic Parameters of Transition Metal Chelates Derived from Schiff Base of 4-Benzoyl- 1-(p-nitrophenyl)-3-methyl-2-pyrazolin-5-ones with Some Diamines.

Abstract

Stability constants and thermodynamic data of Mn²⁺, Co²⁺, Ni²⁺,
Cu²⁺ and Zn²⁺ chelates of Schiff base of 4-benzoyl-1-(p-nitrophenyl)-3-
methyl-2-pyrazolin-5-ones with ethylene diamine, m-phenylene diamine,
benzidine have been determined at 25 and 35 °C in 70:30 (v/v) dioxanewater
media and 0.1 M KNO₃, using Calvin-Bjerrum technique as
applied by Irving and Rossotti. The stability constants at both the temperatures
is found to be Mn < Co < Ni < Cu > Zn for all systems.  ΔG,  ΔH,
and  ΔS for the complexation have been derived.