SYNTHESIS AND CHARACTERIZATION OF HEXADENTATE COBALT(III) COMPLEXES WITH NEW EDTA-TYPE LIGANDS .3. CIRCULAR-DICHROISM OF COBALT(III) COMPLEXES OF ETHYLENEDIAMINE-N,N,N'-TRIACETIC-N'-3-PROPIONIC ACID AND ETHYLENEDIAMINE-N,N-DIACETIC-N',N'-DI-3-PROPIONIC ACID

Cobalt(III) complexes with the hexadentate ligands, ethylenediamine-N, N,N'-triacetate-N'-3-propionate ion (ed3ap) and ethylenediamine-N,N-di acetate-N,N'-di-3-propionate ion (u-eddadp), have been prepared, chrom atographically separated and resolved. Only one of two geometrical iso mers of the [Co(ed3ap)]- complex was isolated. A H-1 NMR spectrum of t his isomer, trans(O5)-[Co(ed3ap)]-, indicates that its six-membered pr opionate chelate ring is bound equatorially to the cobalt(III) ion. Th ere is no similar structural variation possible for the hexadentate u- eddadp ligand. (-)546-trans(O5)-[Co(ed3ap)]- and (+)546-[CO(U-eddadp)] - complexes with a positive CD peak at lowest energy in the first spin -allowed absorption band region are tentatively assigned the A absolut e configuration. Spectral data of these complexes are discussed in rel ation to those of other [Co(edta-type)]- complexes of known structure.