Hydrogenation of olefins catalyzed by Pd(II) complexes containing a perfluoroalkylated S,O-chelating ligand in supercritical CO2 and organic solvents

Pd(II) complexes with the tridentate ligands heptadecafluorodecyl-thiophene-2-carboxylate (L1 = SOSRf1, Rf1 = (CH2)2(CF2)7CF3) and heptadecafluorononil thiophene-2-carboxylate (L2 = SOORf2, Rf2 = (CH2)(CF2)7CF3) have been synthesized, and their catalytic activities for the homogeneous hydrogenation of olefins have been studied with molecular hydrogen in scCO2 and organic solvents. Both perfluoroalkylated-heterocycle ligands potentially have three donor atom sets (SOO/SOS). Depending on the soft-hard interaction between palladium and the donor atoms of the ligands, different activities for the Pd(II) complexes were observed. The nature of the solvent had an effect upon the hydrogenation of olefins. The effects of temperature and H2 pressure on the hydrogenation of styrene were also investigated.