Mechanism of electron transfer reaction of ternary dipicolinatochromium(III) complex involving oxalate as secondary ligand

Journal of Chemical Sciences

Hassan Amroun Ewais1 2¹  Iqbal Mohamed Ibrhium Ismail1¹ 

[1] Department of Chemistry, Faculty of Science, King Abdulaziz University, PO Box 80203, Jeddah 21589, Saudi Arabia$$

关键词: Ternary complex;    electron transfer;    inner-sphere mechanism;    thermodynamic activation parameters.;   

DOI  :  

来源: Indian Academy of Sciences

【 摘 要 】

Mechanism of electron transfer reaction of ternary Mechanism of the oxidation of [CrIII(DPA)(OX)(H2O)]− (DPA = dipicolinate and OX = oxalate) by periodate in aqueous acidic medium has been studied spectrophotometrically over the pH range of 4.45-5.57 at different temperatures. The reaction is first order with respect to both [IO$^{−}_{4}$] and the complex concentration, and it obeys the following rate law: $$d[{ext Cr}^{ext{VI}}]/dt = k_6K_4K_6[{ext IO}^−_4][{ext{Cr}}^{ext{III}}]_{ext{T}}/{([H^+] + K_4) + (K_5[H+] + K_6K_4)[{ext{IO}}^{−}_{4}]}.$$The rate of the reaction increases with increasing pH due to the deprotonation equilibria of the complex. The experimental rate law is consistent with a mechanism in which the deprotonated form [CrIII(DPA)(OX)(OH)]2− is more reactive than the conjugated acid. It is proposed that electron transfer proceeds through an inner-sphere mechanism via coordination of IO$^{−}_{4}$ to chromium(III). Thermodynamic activation parameters were calculated using the transition state theory equation.dipicolinatochromium(III) complex involving oxalate as secondary ligand

【 授权许可】

Unknown