Solid-state reactions in the carbonylchlorobis(triphenylphosphine)iridium(I)–hydrogen chloride system

Abstract

The kinetics of addition of HCl gas to the solid complex [IrClCO(PPh₃)₂] to form the trans-chloro-octahedral species have been studied. The rate-controlling step is chemical reaction at the phase boundary, with an activation energy of 37 kJ mol^–1 and an entropy change of –184 J K^–1 mol^–1. The reverse reaction has an activation energy of 51 kJ mol^–1 and an entropy change of –176 J K^–1 mol^–1. Loss of HCl from the cis-chloro-isomer is again controlled by reaction at the phase boundary with an activation energy of 130 kJ mol^–1 and an entropy change of –92 J K^–1 mol^–1. The enthalpy of dehydrochlorination of each isomer has been measured, and mechanistic implications of the results are discussed.