Interaction of Ni(CO)4, Fe(CO)5, Co2(CO)8 With MgO and Formation of Very Small Metallic Clusters

Publisher Summary This chapter describes a method to study the interaction of Ni(Co) 4 , Fe(Co) 5 , and Co 2 (CO) 8 with MgO and the formation of very small metallic clusters. In this method, the impregnation of a high area support is carried out in conditions of total surface dehydration, absence of solvents, and atmospheric gases. High area MgO samples (∼200 m 2 /g) is obtained directly in the cells by decomposing under high vacuum at 523 K high purity Mg(OH) 2 . Total surface dehydration is achieved by subsequent outgassing at 1073 K under high vacuum conditions. The pellet is then cooled down to room temperature under vacuum and the volatile Ni(CO) 4 , Fe(CO) 5 , and Co 2 (CO) 8 carbonyls is allowed to contact the surface. After each dose, the spectrum of adsorbed species (both I.R. and UV-VIS-Near Infrared diffuse reflectance) is carried out with a Beckman IR 12 and DK-2 spectrometers respectively. The method demonstrate that adsorption of simple carbonyls at R.T. in controlled condition of vacuum and support treatment can produce new polymetallic carbonyls with very few Me atoms. But at higher temperatures (353–523 K) upon CO loss, the new carbonyl clusters can agglomerate (mainly in the Ni case) and/or the metal is oxidized by CO disproportionation.