Behaviour of polynuclear ruthenium carbonyl carboxylates in the presence of hydrogen and/or carbon monoxide

Abstract

The thermal behaviour in the temperature range 293–453 K of [Ru(CO)₂(MeCO₂)₂(PBuⁿ₃)₂],[Ru₂(CO)₄(MeCO₂)₂(PBuⁿ₃)₂] and [Ru₄(CO)₈(MeCO₂)₄(PBuⁿ₃)₂] in hydrocarbon solution, taken separately or in binary mixtures, with each other or with [{Ru₂(CO)₄(MeCO₂)₂}_m], under nitrogen or, alternatively, hydrogen, carbon monoxide, or their mixtures, has been monitored by i.r. spectroscopy under reaction conditions. A deficiency of ligands leads to the formation of larger clusters while their abundance in solution shifts the equilibria towards mononuclear complexes. Under carbon monoxide the formation of ruthenium(0) complexes is obtained from the above compounds. The presence of hydrogen together with carbon monoxide seems to facilitate such evolution of the system probably through the formation of intermediate hydridic derivatives which however were not detected.