Electrochemical properties of [FeIII(L)2Cl2][PF6] and [Fe2III,IIIO(L)4Cl2][PF6]2 [L=2,2′-bipyridine (bpy) and 4,4′-dimethyl-2,2′-bipyridine (dmbpy)]. Crystal structures of the dmbpy derivatives

Abstract

The electrochemical behaviour of the iron(III) complexes [Fe(L)₂Cl₂]⁺ and [Fe₂O(L)₄Cl₂]²⁺ [L=2,2′-bipyridine (bpy) and 4,4′-dimethyl-2,2′-bipyridine (dmbpy)] has been investigated in acetonitrile. Their reduction leads to the iron(II) complex ion [Fe(L)₃]²⁺, accompanied by the release of Cl^- ions and the formation of [FeCl₄]^- ions or by the formation of an unidentified Fe(III) chloro oxide, depending on the starting complex. These two new chloro complexes can be further reduced into Fe(II) species at a more negative potential. In addition, it has been shown that [Fe(L)₂Cl₂]⁺ can be obtained in good yield via the electrochemical oxidation of [Fe(L)₃]²⁺ in the presence of free Cl^- anions, at least for L=dmbpy. The crystal structure of the new mono- and binuclear dmbpy complexes has been determined by X-ray diffraction.