The subtle effects of iron-containing metal surfaces on the reductive carbonylation of RuCl3

Abstract

The use of iron-containing metal surfaces, Fe, Fe–Cr-alloy and stainless steel, for the synthesis of mixed metal Ru–Fe compounds has been studied. The studied process was reductive carbonylation of RuCl₃ in the presence of a metal surface. Reactions were carried out in ethanol solutions under 10–50 bar carbon monoxide pressure at 125 °C using an autoclave. During the reaction the metal surface was oxidized, releasing iron into the solution and acting as a sacrificial source of iron. Under these conditions the corrosion of the metal surface was facile and produced a series of iron-containing species. In addition to the formation of most obvious iron(II) products, such as [Fe(H₂O)₆]²⁺ or [FeCl₂(H₂O)₄] the use of the metal surface also provided a route to novel labile trinuclear [Ru₂Cl₂(µ-Cl)₄(CO)₆FeL₂] (L = H₂O, EtOH) complexes. The stability and reactivity of the [Ru₂Cl₂(µ-Cl)₄(CO)₆FeL₂] complexes were further studied using computational DFT methods. Based on the computational results a reaction route has been suggested for the formation and decomposition of [Ru₂Cl₂(µ-Cl)₄(CO)₆FeL₂].