Ethylene Carbonylation in Methanol and in Aqueous Media by Palladium(II) Catalysts Modified with 1,1'-Bis(dialkylphosphino)ferrocenes

Palladium(II) complexes with the formula [Pd(H2O)(OTs)(P-P)]OTs, where P-P is 1,1?-bis- (dimethylphosphino)ferrocene (dmpf), 1,1?-bis(diethylphosphino)ferrocene (depf), or 1,1?-bis- (diisopropylphosphino)ferrocene (dippf), have been synthesized and used to catalyze the carbonylation of ethylene in MeOH, water, or a 1/1 water/1,4-dioxane mixture. In MeOH, the reactions catalyzed by the dmpf and depf complexes gave alternating polyketone (alt- E-CO), while methyl propanoate and 3-pentanone were selectively produced with the dippf catalyst. The last catalyst was inactive in aqueous solvent. In contrast, the dmpf and depf catalysts were active in either water or water/1,4-dioxane for the copolymerization of CO with ethylene. These two catalysts were efficient also for the terpolymerization of CO with ethylene and propene in MeOH or water/1,4-dioxane. Operando high-pressure NMR experiments and in situ reactions with model compounds have provided useful information to rationalize the activity and selectivity of the catalytic systems investigated.