Stereoselectivity in reactions of metal complexes IX Stereoselective formation of cobalt(III) complexes with new linear pentadentate ligands

The synthesis of cobalt(III) complexes with the new linear pentadentate ligands meso- and racemic 2,6-bis(3S)-3-carboxy-4-methyl-2-azapentylpyridine ( 2 ) are described. Only one of the different possible isomers is obtained from each ligand. The structure of the complexes has been assigned on the basis of their ¹H-NMR and CD spectra. The structure of the aqua-cobalt(III)- 1a and the aqua-cobalt(III)- 1b has been confirmed by X-ray analysis. Partial resolution of optical antipodes of the aquacobalt(III)- 1b was achieved by column chromatography and a tentative assignment of their absolute configuration is made.