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. Λ(R)-β-[Co(edda)(en)]+ isomerized to the Λ(S,S)-α-isomer with an optical purity (o.p.) of ca. 45%. In the reactions of three isomers of [Co(edda)(gly)], Λ(R)-β-fac(O) isomerized to Λ(R)-β-mer(O) (o.p.: ca. 100%) and Λ(S,S)-α-mer(O) (o.p.: ca. 33%), Λ(R)-β-mer(O) to Λ(R)-β-fac(O) (o.p.: ca. 65%) and Λ(S,S)-α-mer(O) (o.p.: ca. 40%), and Λ(S,S)-α-mer(O) to Λ(R)-β-fac(O) (o.p.: ca. 50%) and Λ(R)-β-mer(O) (o.p.: ca. 60%). These results were explained on the basis of a Co–O bond-rupture mechanism.