The decarbonylation and the structural transformation of co(2)(CO)(6)(PBu3)(2) supported on ZrO2, Al2O3, TiO2 and SiO2 have been studied by IR spectroscopy, UV diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and temperature-programmed decomposition technique. It is seen that when the complex is supported on various oxides, the frequency bands of the terminal carbonyls shift to low wave numbers respectively. The order of v (CO) is, complex/TiO2=complex/SiO2, complex/Al2O3, complex/ZrO2. The position of the UV-DRS peaks for supported complexes, which are related to the nature of Co-Co bond and Co-Co (ligand) charge tranfer, are essentially the same as that for unsupported complex. It is found that when these supported complexes are heated in vacuum, intensity of the terminal carbonyl of those supported on ZrO2 and Al2O3 diminishes somewhat with the increasing of temperature, and at the same time intensity of the bridged carbonyl increases. As the temperature is raised to 300'C and 200'C, the carbonyl bands disappear respectively. However, the C-H frequency bands persist in the IR spectra, showing that the phosphine ligands still exist on the surface. When CO is admitted to these decarbonylated samples, the frequency bands of absorbed CO are observed, it is noticed that as the samples exposed to air, the bands disappear at once. The carbonyl bands of complexes supported on TiO2 and SiO2 disappear completely at 150'C and no bands of bridged carbonyl appear, on these decarbonylated samples CO can not be absorbed. The decarbonylation processes of these supported complexes in vacuum and air were investigated According the experimental results, the structural transformation of surface complexes on various oxides are proposed respectively. In addition, the surface reaction of supported complexes in H-2 and He atmosphere during TDPE was also investigated.
