Hybrid materials for catalysis? Design of new phosphonate-based supported catalysts for the hydrogenation of ketones under hydrogen pressure

Supported rhodium. and iridium. 2,2 ' -bipyridine complexes were prepared f or the hydrogenation of aromatic ketones under hydrogen pressure. The key f eature of the immobilization process is the functionalization of the 2,2 ' -bipyridine unit with two phosphonic acid moieties, thus allowing the coval ent grafting of the catalytic complex onto in situ generated titanium oxide particles. A very good catalytic activity is observed with the resulting m aterials that compares well with the homogeneous parent system and gives ev idence that the major part of the catalytic sites are readily accessible. M oreover, the catalyst can be reused, and no significant rhodium. leaching i s observed.