Stereochemistry of Cobalt(III) Complexes with Thioethers. I. Circular Dichroism Spectra of Complexes with Bi- or Terdentate Thioethers

Abstract
Five (bidentate-N,S or -O,S)bis(ethylenediamine)cobalt(III) complexes have been optically resolved and their absolute configurations deduced from their circular dichroism (CD) spectra, where bidentate-N,S or -O,S are NH2(CH2)2S−, NH2(CH2)2SR (R=CH3 and C2H5), and CH3S(CH2)nCO2− (n=1 and 2). The chromatographic, CD, and NMR behaviors suggest that the thioether donor atoms are coordinated stereoselectively producing the Δ-(S) or Λ-(R) complexes. Three (terdentate-N,S,O)[1,1,1-tris(aminomethyl) ethane] cobalt(III) complexes of NH2(CH2)2SCH2CO2−, NH2(CH2)2S(CH2)2CO2−, and l-CH3SCH2CH(NH2)CO2− have been prepared and the complexes of the former two ligands optically resolved; the absolute configurations have been discussed on the basis of the CD spectra.