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 Δ or Λ-diastereoisomers.

Graphical abstractThe 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, are reported; the formation of [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 Δ or Λ-diastereoisomers.Figure optionsDownload full-size imageDownload as PowerPoint slide