Bis-chelating ligands based on bipyridine or bis-isoquinoline moieties with controlled rotation around the C-C bond

Two unprecedented types of ligands with C2 symmetry, with comparable essential features, are proposed as supports for metal centres in bimetallic promotion of organic syntheses. Preparation and characterization of bis-chelating bipyridine ligands A and X-ray analysis of a related palladium binuclear complex are described. Synthesis and characterization of a dialdehyde intermediate for type B ligands are also reported.