Hydroformylation of styrene catalyzed by a rhodium thiolate binuclear catalyst supported on a cationic exchange resin

The binuclear complex [Rh2(μ-S(CH2)2NMe2)(cod)2] 1 (cod=1,5- cyclooctadiene) was anchored to a sulfonic exchange resin through the residual amine groups. The reaction of the immobilized complex with CO and PPh3 yielded the catalytically active complex [Rh2(μ- S(CH2)2NHMe2)2(CO)2(PPh3)2]2+ supported in the polymer matrix. When methanol was used as solvent, the metal complex loaded cationic resin behaved as a multifunctional catalyst, since it was active in the hydroformylation of styrene and the subsequent formation of the acetals, directly rendering 1,1- dimethoxy-2-phenylpropane in 85% selectivity. Furthermore, the immobilized catalyst can be separated from the reaction mixture and recycled. A homogeneous model of the supported catalyst was generated by reacting complex 1 with HTsO, PPh3, and CO. Thus, the methanol soluble complex [Rh2(μ- S(CH2)2NHMe2)2(CO)2(PPh3)2](TsO)2 was also found to be active in the hydroformylation of styrene yielding identical selectivity in the branched isomer to that of the immobilized catalyst, although the latter is much slower (20-fold) than the homogeneous catalyst.