Involvement of an acetato ligand in the reductive elimination step of the rhodium-catalyzed methanol carbonylation
Résumé
the complex cis-[PPN][RhI2(CO)2] 1 is produced in high yield by reaction under CO of RhI3 in DMF at 160°C, followed by metathesis of the [NH2Me2]+ with bis(triphenylphosphoranylidene)ammonium]chloride, ([PPN]Cl). Under CO, complex 1 reacts in neat CH3I to afford [PPN][RhI3(COMe)(CO)2] 2. At low water content the reductive elimination reaction was shown by Infrared, 1H and 13C NMR, kinetics measurements and DFT calculations to involve two steps: the substitution of an iodo ligand by an acetate ligand followed by the reductive elimination of acetic anhydride from the [PPN][RhI2(COMe)(OCOMe)(CO)2] 3 intermediate regenerate 1.