Chiral metal complexes. 6. The kinetically controlled stereoselective synthesis of ternary Co(III) complexes of the type [Co(phen)₂(S-aminoacidate)]ⁿ⁺

The complexes Λ[Co(phen)₂(aa)]²⁺, where aa is the singly charged anion of the α-amino acids S-glutamine, S-asparagine, S-glutamic acid and S-aspartic acid, and phen is 1,10-phenanthroline, may be synthesized stereospecifically under certain conditions by the reaction of the amino acid with Δ,Λ[Co(phen)₂CO₃]⁺. Kinetic, rather than thermodynamic, influences are responsible for the reaction products observed. It is evident that both diastereoisomers of the bis-phen complex form initially, but the rate of decomposition of the Δ-isomer is considerably faster than that of the Λ-isomer. The results have been used to reinterpret some earlier work on chiral discriminations in related complexes containing 1,2-diaminoethane, and recent results concerning the phen complexes containing glycine, S-alanine, S-phenylalanine, S-leucine, S-isoleucine and S-valine.