Anion effects in the formation of the active catalyst in the Ruhrchemie - Rhône-Poulenc aqueous biphasic hydroformylation process. Are there any?

The water soluble [Rh(OAc)(CO)(mtppms)2] containing monosulfonated triphenylphosphine ligands was prepared for the first time and its hydrogenation was studied in aqueous solutions. In the presence of additional mtppms, the reaction yielded [RhH(CO)(mtppms)3], a close analogue of [RhH(CO)(mtppts)3], the immediate catalyst precursor in the Ruhrchemie ? Rh©one-Poulenc aqueous biphasic hydroformylation process. The extent of the [Rh(OAc)(CO)(mtppms)2] ? [RhH(CO)(mtppms)3] transformation strongly depended on the solution pH, similar to the case of the hydrogenation of [RhCl(CO)(mtppms)2] studied earlier. In this respect, RhCl3?aq and Rh(OAc)3?aq can be used equally well for the in situ preformation of [RhH(CO)(mtppts)3], although the latter is the preferred choice in the industrial process.