Mechanistic aspects of the reduction of ruthenium(III) catalyzed hexacyanoferrate(III) by atenolol in alkaline medium

The kinetics of Ru-III catalyzed reduction of hexacyanoferrate(III) [Fe(CN)(6)](3-), by atenolol in alkaline medium at constant ionic strength (0.80 mol dm(-3))has been studied spectrophotometrically, using a rapid kinetic accessory. The reaction between atenolol and [Fe(CN)(6)](3-) in alkaline medium exhibits 1:2 stoichiometry [atenolol:Fe(CN)(6)(3-)]. The reaction showed first order kinetics in [Fe(CN)(6)](3-) concentration and apparent less than unit order dependence, each in atenolol and alkali concentrations. Effect of added products, ionic strength and dielectric constant of the reaction medium have been investigated. A retarding effect was observed by one of the products i.e., hexacyanoferrate(II). The main products were identified by i.r., n.m.r., fluorimetric and mass spectral studies. A mechanism involving the formation of a complex between the atenolol and the hydroxylated species of ruthenium(III) has been proposed. The active species of oxidant and catalyst were [Fe(CN)(6)](3-) and [Ru (H2O)(5)OH](2+), respectively. The reaction constants involved in the mechanism were evaluated. The activation parameters were computed with respect to the slow step of the mechanism, and discussed.