Taking too many precautions in making a catalyst is never a loss of time: A lesson we learned at our own expense

The reaction in MeOH between the bis-chelate complex [Pd(dppe)(2)](OAc)(2) and Pd(OAc)(2) to give the monochelate product Pd(OAc)(2)(dppe) is assisted by free acetate ion, and its rate is proportional to the concentrations of both reagents (dppe = 1,2-bis(diphenylphosphino)ethane). The aggregation of Pd(OAc)(2) in CH2Cl2 and the low dielectric constant of this solvent are proposed to be important factors in accelerating the formation of Pd(OAc)(2)(dppe) in CH2Cl2.