Formation of trans(N)-bis(amino acidato)(2,2′-bipyridine)cobalt(III) complexes following the UV irradiation of amino acidatobis(2,2′bipyridine)cobalt(III) complexes in dimethyl sulfoxide

Abstract

The products from the steady state photolysis of [Co(aa)(2,2′-bpy)₂]²⁺ (aa = glycinate (gly), alaninate (ala) or 2-aminoisobutyrate (aib)) complexes in dmso have been identified, and include the trans(N)-[Co(aa)₂(2,2′-bpy)]⁺ complex ions. This contrasts with photolyses in aqueous solution where the [Co(2,2′-bpy)₃]³⁺ ion is produced. This solvent dependence can be attributed to the secondary reactions of the photolysis products, rather than to different photochemistry. Electrochemical data have been gathered on a range of [Co(aa)_x(2,2′-bpy)_y]^(3–x)+ compounds and are used to help rationalise the observed selectivity. Two of the products have been characterised by X-ray crystallography: (Δ-SS/Λ-RR)-trans(N)-[Co(ala)₂(2,2′-bpy)]ClO₄·H₂O and trans(N)-[Co(aib)₂(2,2′-bpy)]ClO₄· NaClO₄·0.5H₂O.