Kinetic study of the reaction IrCl 2–6+IrBr 3–6⇌IrCl 3–6+IrBr 2–6

Abstract

The temperature-jump method has been used to determine the rate constants for the reaction[graphic omitted] over a range of temperatures. At 20°C and at an ionic strength of 0.1 M, kf= 1.2×10⁷ M^–1 sec^–1 and k_r= 1.8×10⁶ M^–1 sec^–1. The forward and reverse activation energies are 5.7 and 7.5 kcal/mole, respectively. In addition, the rate constant for the exchange reaction [graphic omitted]was determined; k= 2.3×10⁵ M^–1 sec^–1 at 25°C and at an ionic strength of 0.1 M. The net reaction was studied in the presence of so-called inert electrolytes such as LiNO₃, KNO₃, NH₄Cl and N(CH₃)₄Cl. These salts affected the relaxation time, cations being more effective than anions. The Marcus theory was applied to these reactions, the calculated rate constants agreeing with experiment.