Tris-chelate complexes with chiral ligands : in search of diastereoisomeric selectivity with remote stereogenic centres

The chiral ligands, 4,4`-bis(1S,2R,4S)-(-)-bornyloxy)-2,2`-bipyridine, (1S,2R,4S)-1, and 4,4`-bis(1R,2S,4R)-(+)-bornyloxy)-2,2`-bipyridine, (1R,2S,4R)-1, have been prepared and characterized by spectroscopic techniques and, for (1S,2R,4S)-1, by single crystal X-ray diffraction. Despite the use of enantiomerically pure ligands, the formation of the complexes [Fe((1S,2R,4S)-1)(3)](2+), [Ru((1S,2R,4S)-1)(3)](2+), [Ru((1S,2R,4S)-1)(bpy)(2)](2+) and [Ru((1R,2S,4R)-1)(bpy)(2)](2+) proceeds without preference for either the Delta or Lambda-diastereoisomers.