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 for the hydrogenation of aromatic ketones under hydrogen pressure. The key feature of the immobilization process is the functionalization of the 2,2 ' -bipyridine unit with two phosphonic acid moieties, thus allowing the covalent grafting of the catalytic complex onto in situ generated titanium oxide particles. A very good catalytic activity is observed with the resulting materials that compares well with the homogeneous parent system and gives evidence that the major part of the catalytic sites are readily accessible. Moreover, the catalyst can be reused, and no significant rhodium. leaching is observed.