STEREOSELECTIVE ISOMERIZATION-REACTIONS OF THE (ETHYLENEDIAMINE-N,N'-DIACETATO)-(ETHYLENEDIAMINE)COBALT(III) AND (ETHYLENEDIAMINE-N,N'-DIACETATO)-(GLYCINATO)COBALT(III) COMPLEXES IN A BASIC AQUEOUS-SOLUTION

Isomerization reactions of the [Co(edda)(en)]+ and [Co(edda)(gly)] systems were studied in a basic aqueous solution. LAMBDA-(R)-beta-[Co(edda)(en)]+ isomerized to the LAMBDA-(S,S)-alpha-isomer with an optical purity (o.p.) of ca. 45%. In the reactions of three isomers of [Co(edda)(gly)], LAMBDA-(R)-beta-fac(O) isomerized to LAMBDA-(R)-beta-mer(O) (o.p.: ca. 100%) and LAMBDA-(S,S)-alpha-mer(O) (o.p.: ca. 33%), LAMBDA-(R)-beta-mer(O) to LAMBDA-(R)-beta-fac(O) (o.p.: ca. 65%) and LAMBDA-(S,S)-alpha-mer(O) (o.p.: ca. 40%), and LAMBDA-(S,S)-alpha-mer(O) to LAMBDA-(R)-beta-fac(O) (o.p.: ca. 50%) and LAMBDA-(R)-beta-mer(O) (o.p.: ca. 60%). These results were explained on the basis of a Co-O bond-rupture mechanism.