CO-59 NMR SPECTROSCOPIC CHIRAL DISCRIMINATION OF [CO(EN)(3)](3+) ENANTIOMERS IN IONIC INTERACTING SYSTEMS

Formation of diastereomers of Delta- and Lambda-[Co(en)(3)](3+) was investigated in aqueous chiral-electrolyte solutions using (59)CoNMR spectroscopy. The chiral electrolytes used were alkali salts for L- and D-tartrates, bis(mu-(-)(589)-tartrato)diantimonate(III), N-dodecanoyl-L-(and D-)alaninate, N-dodecanoyl-L-threoninate, and N-hexadecanoyl-L-prolinate. The (59)CoNMR parameters for the [Co(en)(3)](3+) group were different between the enantiomers in most cases. The NMR parameters used for chiral discrimination were chemical shifts (in simple electrolyte and micellar solutions), relaxation rates (in simple electrolyte and micellar solutions), peak areas (in micellar solutions), and quadrupole splittings (in liquid crystalline solutions). The larger values of the relaxation rates suggest stronger interactions. On the other hand, the magnitude of the chemical shift change was not simply related to the extent of the interactions. For a chemical shift, the contribution of a geometrical factor seems to be dominant in systems having local anisotropy in the interaction.