Hydridorhodium(I) complexes with amphiphilic polyether phosphines: NMR study and biphasic hydroformylation of 1-octene

The formation of hydridorhodium(I) complexes with the amphiphilic phosphines 4-(R)C6H4(OCH2CH2)nPPh2 (R=2,2,4,4-tetramethylbutyl, n=1, ) was studied by NMR methods and IR spectroscopy. Two approaches were used: (1) the substitution reaction of triphenylphosphine in RhH(CO)(PPh3)3 by an amphiphilic phosphine and (2) a reaction between the precursor Rh(acac)(CO)2, syngas and the amphiphilic ligand in hydroformylation reaction conditions. Both approaches show the formation of P-coordinated hydridorhodium(I) complexes, and no relevant chelated (P, O) complexes were recognised. The biphasic rhodium-catalysed hydroformylation of 1-octene with the following water-soluble amphiphilic phosphines was studied: 4-(R)C6H4(OCH2CH2)nP(Ph)CH2CH2SO3Na (R=2,2,4,4-tetramethylbutyl, ; R=n-nonyl, ), and RP(Ph)CH2CH2SO3Na (R=n-octyl, CH3(OCH2CH2)2OCH2CH2). Ligands with a hydrophobic group and a short polyether chain led to the higher conversion. This result is ascribed to the ability of these ligands to increase the metal concentration in the organic phase.