Thermokinetic study on the complexation reaction of the first-row transitional metal chlorides with histidine

✍ Scribed by San-Ping Chen; Sheng-Li Gao; Qi-Zhen Shi

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 557 KB
• Volume: 22
• Category: Article
• ISSN: 0256-7660
• DOI: 10.1002/cjoc.20040221012

✦ Synopsis

Abstract

The enthalpy change of the complexation reactions of the first‐row transitional metal chlorides including CrCl~3~, MnCl~2~, FeCl~2~, CoCl~2~, NiCl~2~ and CuCl~2~ with L‐α‐histidine in water were determined by a microcalorimeter at 298.15‐323.15 K. The standard enthalpy of formation of Cr(His) (aq) and M(His) (aq) (M=Mn, Fe, Co, Ni and Cu) were calculated. Based on the thermodynamic and kinetic equations of the reactions, three thermodynamic parameters (the activation enthalpy, the activation entropy, the activation free energy), the rate constants, and three kinetic parameters (the apparent activation energy, the pre‐exponential constant and the reaction order) are obtained. The solid complexes of CrCl~3~, MnCl~2~, FeCl~2~, CoCl~2~, NiCl~2~ and CuCl~2~ with histidine were prepared and identified as Cr(His)~2~Cl~3~·H~2~O. Mn(His)~2~Cl~2~·4H~2~O. Fe(His)~2~Cl~2~·H~2~O, Co(His)~2~Cl~2~·H~2~O, Ni(His)~2~Cl~2~·H~2~O and CU(HiS)~2~Cl~2~·H~2~O by chemical and elemental analyses. The bonding characteristics of these complexes were characterized by R as well. The results showed that, with the atomic number increasing, three thermodynamic parameters, ΔG, ΔH and ΔS of the complexation reaction of these metal chlorides with L‐α‐histidine in water present an analogy regularity.