Notes. A kinetic investigation of the base-catalysed deuterium-exchange reaction of tris(2,2′-bipyridine)osmium(II) ion in dimethyl sulphoxide solution

Abstract

A complete deuterium exchange of the protons is observed in the complex ion [Os(bipy)₃]²⁺(bipy = 2,2′-bipyridine) dissolved in [D₆]dimethyl sulphoxide containing NaOD and D₂O. The reaction rates of the different positions were found to decrease in the order: 3,3′ 5,5′ > 6,6′ > 4,4′. The rate of exchange of the 3,3′-protons followed a simple second-order expression: rate =k₂[Os(bipy)₃²⁺][NaOD], indicating attack of OD^– on the protons in the rate-determining step.