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

Two unprecedented types of ligands, with comparable essential coordination features, are proposed as supports for metal centres in bimetallic promotion of organic syntheses, including asymmetric catalytic processes. Synthesis and characterization of the bis-chelating bipyridine ligands A with C2 symmetry and X-ray analysis of one bipyridine diimine palladium binuclear complex are described. Synthesis and X-ray analysis of the bis-phenylimino derivative of a dibenzodioxepine dialdehyde are also reported. This dialdehyde is a key intermediate in the attainment of bis-isoquinoline ligands B with the same symmetry as A.