SYNTHESIS OF A NEW FAMILY OF WATER-SOLUBLE TERTIARY PHOSPHINE-LIGANDS AND OF THEIR RHODIUM(I) COMPLEXES - OLEFIN HYDROGENATION IN AQUEOUS AND BIPHASIC MEDIA

The series of phosphonium phosphines [Ph2P(CH2)nPMe3]X (n = 2, 3, 6, 10; X = NO3-, Cl-, PF6-), henceforth II-, III-, VI- and X-phosphos, respectively, have been prepared and characterized. The ligands react with [NBDRhCl]2 (NBD = norbornadiene) to form the complexes [NBDRhCl(n-phosphos)]X, one of which, [NBDRhCl(II-phophos)]PF6, has been characterized crystallographically. The 1:1 complexes [NBDRhCl(n-phophos)]X react with a second equivalent of ligand to form the complexes [NBDRh(n-phophos)2]X, which form very active olefin hydrogenation catalysts in aqueous and aqueous-organic biphasic systems. The effect of chain length on activity is very significant, the complex of VI-phophos forming the most active catalyst.