Methylruthenium carbidocarbonyl clusters supported on inorganic oxides: characterization and selective acetaldehyde formation

Abstract

The clusters [Ru₆C(CO)₁₆Me]^– supported on SiO₂, Al₂O₃ and TiO₂ were characterized by means of extended X-ray absorption fine structure (EXAFS), temperature-programmed desorption (TPD) and Fourier-transform IR spectroscopy in relation to developments of new catalytic systems. The EXAFS analysis revealed that the Ru₆C cluster framework which has an interstitial carbon atom was stable at 473 (SiO₂), 523 (Al₂O₃) and 473 K (TiO₂) under CO or CO + H₂. The supported clusters produced methane upon heating in vacuum by the reaction with surface hydrogen-bonded OH groups, whereas in the presence of CO + H₂ acetaldehyde was preferably produced, unlike [Ru₆C(CO)₁₆Me]^– in a homogeneous system where only methane was formed. The selectivity to acetaldehyde was larger with SiO₂(77%) than with Al₂O₃(15) or TiO₂(10%).