硫代草酸铁(Ⅲ)配合物的酸性水解动力学

KINETICS OF THE ACID HYDROLYSIS OF (THIOOXALATO-O,S)FERRIC COMPLEX

本文研究了配合物KCaFe(SC_2O_3)_3·3H_2O在30、40、50℃的Clark-Lubs缓冲溶液中的酸性水解动力学。测定了不同温度和酸度的准一级速度常数K_(th),K_(th)。与[H^(+1)呈直线关系,K_(th)=K_1[H^+]+k_2,K_1是与平衡常数和速度常数k_1有关的常数,k_2为速度常数。提出的反应机制认为是通过不对称配位原子形成共轭酸,再发生铁-硫键破裂,酸性水解的活化参数△H^(?)=78.81±1.18kJ.mol^(-1),△S^(?)=-46.67±0.68J·K^(-1)·mol^(-1),与文献报导的具有不对称配位原子螯合物的酸性催化离解的数值相近。

The kinetics of the acid hydrolysis of the complex KCaFe(SC2O3)3 · 3H2O has been investigated in Cleark-Lubs buffer at 30,40,501, pseudo first-order rate constants Kth in different acidity and temperature were determined.The plot of Kth vs.[H+] is a straight line,Kth = K1 [H+] + k2, K1 is constant related to equilibrium constant K and rate constant k1,k22 is rate constant. The mechanism suggested was considered through the formation of conjugate acid of unsymmetrical coordinated atoms ,then ferricsulfur bond was broken. Activation parameters are:ΔH =78.81±1.18kJ·mol-1 , and ΔS=-46.67± 0.68 JK-1·mol-1 in pH1.00.The values were agreement with the activation parameters of acid-catalysed aquation of unsymmerical chelate complex.