Synthesis, spectroscopic, magnetic and electrochemical properties of diruthenium-(II,III) and -(III,III) complexes containing the mixed-carboxylato ligand systems CH3CO2––CF3CO2– and C6H5CO2––CF3CO2–

Abstract

The interaction of the Ru₂⁵⁺ tetra-µ-carboxylates [Ru₂(O₂CR)₄Cl](R = CH₃ or C₆H₅) with alcoholic solutions of Ag(O₂CCF₃) yields the Ru₂⁵⁺ mixed-carboxylato, monotrifluoroacetato derivatives [Ru₂(O₂CR)₄(O₂CCF₃)L₂](L = H₂O or MeOH). The omission of alcohol and inclusion of trifluoroacetic acid in the reaction medium directs the synthesis to the Ru₂⁵⁺ mixed-carboxylato, tris(trifluoroacetato) complexes, [Ru₂(O₂CR)₂(O₂CCF₃)₃(H₂O)_0.5]. Under aerobic conditions the oxidized, paramagnetic Ru₂⁶⁺ tetrakis(trifluoroacetato) complex [Ru₂(O₂CCH₃)₂(O₂CCF₃)₄(H₂O)₂] is obtained. Conductivity measurements, electronic and i.r. absorption spectra, and magnetic susceptibility data are given. Cyclic voltammetry measuements show that increased numbers of CF₃CO₂^– ligands in the complexes are responsible for an anodic shift in the potential of the Ru₂⁵⁺⇌ Ru₂⁴⁺ couple. Structures are proposed for the tris- and tetrakis-(trifluoroacetato) complexes.