Kinetics and thermodynamics of the oxidative-addition reaction of iodine with the dicyanoaurate(I) ion in aqueous solution

Abstract

The equilibrium constant for the reaction Au(CN)2–+ I2⇌ Au(CN)2I2– has been measured. The reaction obeys the rate expression d[Au(CN)2I2–]/dt=k2[Au(CN)2–][I2]+k2′[Au(CN)2–][I3–] with k2=(2·8 ± 0·2)× 104 l mol–1 s–1 and k2′=(4·40 ± 0·08)× 106 l mol–1 s–1 at 25 °C and µ= 0·10M, and is unusual in having kI2/kI3–= 0·0064 (normally kI2/kI3– > 1).