Optically active co-ordination compounds. Part XXXVII. Circular dichroism of labile trioxalatometallate(III) complexes

Abstract

From solutions of kinetically labile or inert racemic complexes of the type [M(C₂O₄)₃]^3–(M = V, Cr, Mn, Fe, or Co), addition of the resolving ions Λ- or Δ-[M′(en)₃]³⁺(M′= Co or Rh; en = ethylenediamine) causes precipitation of diastereoisomeric salts [M′(en)₃][M(C₂O₄)₃]·xH₂O. All the salts except that of Fe^III show circular dichroism in the visible region when measured as dispersions in CsCl discs. All the salts are isomorphous, so that stereochemical correlations are possible, using the rule of less-soluble diastereoisomers. Absolute configurations are assigned to the trioxalato-species. The circular dichroism spectra also confirm the Λ configuration of (–)[Rh(en)₃]³⁺.