When Λ-α-[Co(R-picpn)Cl2)]Cl)4 (R-picpn = (3R)3-methyl 1,6-di(2-pyridyl)-2,5-diazahexane) is reacted with sodium oxalate in aqueous solution, the complex Λ-α[Co(R-picpn)(ox)]ClO4 is obtained. This reaction represents a total inversion of absolute configuration with respect to the metal centre. When isolated as the iodide salt, [Co(R-picpn)(ox)]I·1.5H2O, the cationic product is obtained as a mixture of Δ-α and Λ-β diastereoisomers with a minor quantity of the Λ-αform. These isomeric ratios appear to be influenced by differences in reaction conditions, including exposure to light.
Bibliographical noteErratum can be found in Inorganica Chimica Acta, 83(2), p. 143, 1984.