Equilibrium and kinetic study for the reaction of Trans-K[Cr(ox}z(H20)2).3Hz0 with 4-aminoantipyrine

new complex of Cr(UI) has been prepared. Tbe kinetics and equi librium study of the substitution reaction for the complex TransK[ Cr(ox)2(H202].3H20 {TI }, with 4-aminoantipyrine {AAP}, bave been performed in aqucous= medja at (pH = 4.9. 5.6 and 6.0) (f..l=0.4M NaNO 3). Activation parameters for the reactions are (Ea1= 1.891 kCal mor^-1 Δ H=89.29 kCal mor^-1 and ΔS^++1 = 0.281 Cal. mor^-1 and (Ea2=0.487kCal mor^-1 ; ΔH^++2 =6.2.03 kCal mor^-1 and ΔS^++2 = -92.8 Cal mor^-1 The observed rate constants are in good agreement with substitution reaction of the complex with amino acids( I) and other anions(2).