Synthesis of rhodium carbonyl compounds at atmospheric pressure. III. Synthesis of Rh 4(CO) 12 and of Rh 6(CO) 16

Abstract

Rh 4(CO) 12 was obtained in moderate yield (60 %) by reducing Rh 2(CO) 4Cl 2 at atmospheric pressure and room temperature with carbon monoxide in the presence of water. In organic solvents and in the presence of minor quantities of water Rh 6(CO) 16 was obtained (30%). The same reaction have been carried out under alkaline conditions: Rh 4(CO) 12 was obtained using hexane containing suspended sodium hydrogen carbonate (82%), and Rh 6(CO) 16 in water-alcohol in the presence of lithium acetate (77%). These last, two syntheses seem to be of particular practical significance, owing to easy availability of Rh 2(CO) 4Cl 2, high yield and extreme simplicity. The physical and chemical properties of the two cluster carbonyls are discussed.