INTERACTION OF CARBON-MONOXIDE WITH RU-GAMMA-AL2O3 - AN ELECTRON-SPIN-RESONANCE INVESTIGATION

Interaction of carbon monoxide with Ru/ γ-Al2O3 leads to the formation of RuI and RuIII carbonyl derivatives. The relative amounts of the two species are a function of the temperature used in decarbonylating the Ru3(CO)12/ γ-Al2O3 precursor. The thermal and vacuum stabilities of the RuI derivative [g⊥ = 2.050, g∥ = 1.992, A∥(99Ru, 101Ru) = 28 G] and the RuIII derivative (g∥ = 2.046, g⊥ = 2.005) are different, the RuIII species being the more stable. The Ru-CO bond strength of these carbonyls is high in comparison with that of the analogous Rh/ γ-Al2O3 carbonyl derivatives. The enhanced bond strength may account for the difference in the catalytic behaviour between the Ru and Rh systems.