Kinetic study of the complex reaction between copper(II) and 2-(2′-hydroxy-3′-methoxyphenyl)benzothiazole

Abstract

2-(2′-Hydroxy-3′-methoxyphenyl)benzothiazole reacts with copper(II) in an ethanol/water mixture to form an O,S chelate which exhibits the remarkable property of changing the chelation site above a pH of ca. 5.0, to the O,N site. The detailed kinetics of this reaction in an ethanol/water mixture (3:1) at a temperature of 25 °C was investigated using a stopped-flow spectrophotometric technique employing a wavelength of 400 nm. The initial complex, Cu(O,S), is formed via a fast, reversible second-order complex formation step whereupon the formation of the Cu (O,N) follows first order kinetics. The Cu(O,N) complex is, however, unstable towards internal electron exchange and after the reaction is..