Synthesis, characterization and reversible binding of dioxygen and carbon monoxide in ruthenium(III) schiff-base complexes. Effect of equatorial substitution on the O₂ and Co affinities

Abstract

Synthesis of a series of ruthenium(III) Schiff-base complexes of the type K[RuLX₂] (where L = dibasic Schiff bases derived from methoxy, chloro substituted salicyl-aldehyde with o-phenylenediamine, propylenediamine and ethylenediamine, X = chloride) have been accomplished. The complexes were characterized by physicochemical methods. The formation of Ru^IV superoxo complexes was confirmed electrochemically and by IR spectroscopy. The reversible binding of oxygen and carbon monoxide to these complexes were carried out in DMF at 10, 25 and 40°C. The substituents on salicylaldehyde increase the value of equilibrium constants KO₂ and K_CO for the oxygenation and carbonylation reactions. The thermodynamic parameters ΔH⁰, ΔG⁰ and ΔS⁰ for oxygenation and carbonylation were evaluated.