Electron transfer reaction in the chromium(VI)-manganese(II) system in the presence of ethylenediaminetetraacetic acid (EDTA)

Author： Babu Prabijna

Publisher： Springer Publishing Company

ISSN： 0340-4285

Source： Transition Metal Chemistry, Vol.29, Iss.8, 2004-11, pp. : 885-892

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

Upon addition of Cr^VI to a solution of ethylenediaminetetraacetic acid (EDTA) and Mn^II, a transient species appears which has an absorption maximum at 500 nm. Kinetic studies of the outer-sphere oxidation of the Mn^II-EDTA complex with the Cr^VI-EDTA complex have been investigated by visible spectrophotometry at 25 °C. The formation of a transient species has been characterized spectrophotometrically and the encounter complex formation constants have been determined (K_OS = 1.75 × 10² and 1.66 × 10³ mol^-2 dm⁶ for [EDTA] and [Mn^II] variations, respectively). The effect of total [EDTA], [Mn^II], [Cr^VI] and [HClO₄] on the rate of the reaction was determined. On addition of HClO₄, there is a decrease in the rate constants. The reaction product is the Cr^III-EDTA complex with _max = 400 and 550 nm. On the basis of the various observations and product characterization a most plausible outer-sphere mechanism has been envisaged.