A kinetic and mechanistic study of the oxidative addition of diaryl ditellurides to trans-carbonylchlorobis(triphenylphosphine)iridium(I) in toluene

Abstract

The oxidative addition of diaryl ditellurides to [IrCl(CO)(PPh₃)₂] in toluene solution has been followed by visible spectrophotometry. The reaction is first order in the concentration of each reagent. An e.s.r. signal can be detected from the reacting solution. An i.r. spectroscopic study of the reaction in carbon tetrachloride shows the relatively rapid formation of an adduct before the final stages of the process occur. Rate constants and activation parameters for four different ditellurides have been determined. These parameters vary widely with the substituents on the aryl rings of the ditellurides. A mechanism is suggested which involves the initial addition of ditelluride to iridium(II), followed by homolytic cleavage of the Te–Te bond and formation of the final trans product.