Preparation and Spectroscopic Studies of Stereoisomers of the Triscobalt(III) Complex

Article abstract of DOI:10.1246/bcsj.55.1454

Three, fac-Δ, fac-Λ, and mer-Δ, of four possible diastereomers of the ³⁺ complex (S-phtn=(S)-1-phenyl-1,3-propanediamine) were obtained by two methods, a reaction between trans-⁺ and S-phtn in DMSO (dimethyl sulfoxide), and oxidation of a DMSO solution containing Co(II) ions and S-phtn with air in the presence of active charcoal.Neither method yielded the mer-Λ isomer.The absorption and circular dichroism spectra of the isomers were recorded in water in the absence and presence of Na2SO4, and in DMSO.The shifts of the first absorption bands caused by changing solvents and the changes of circular dichroism spectra caused by the addition of sulfate ions seem to be related with the conformational instability of the flexible six-membered chelate ring in the complexes.The tetraammine complex of S-phtn was also prepared.