Chemical reactivity of solid [PtnC60] towards carbon monoxide

Evidence of chemical reactivity of solid platinum-fullerene [Pt_nC₆₀] compounds towards carbon monoxide is presented. The interaction was systematically studied by means of infrared spectroscopy, X-ray powder diffraction and thermogravimetric analysis. The interaction of carbon monoxide, even under low pressure, is confirmed by the appearance of infrared absorption bands in the CO stretching region at 2064, 2014 and 1991 cm⁻¹ for the carbonylation products. The exceptions were those products with low Pt:C₆₀ ratios, which also displayed bands at 1870 and 1830 cm⁻¹. The data suggest that the CO coordination depends on the specific morphology of the solids, the original Pt:C₆₀ ratio, and the carbon monoxide nominal pressure. Therefore, these results indicate the formation of [(CO)_xPt]_m species supported in a fullerene matrix mixed with [Pt_n−mC₆₀] compounds. As there is a competition between carbon monoxide and fullerene molecules for the electronic density at the platinum centers, the nature of the CO interaction with [Pt_nC₆₀] was found to be destructive, leading to the displacement of the latter. Nevertheless, the platinum-carbonyl species formed presents relatively high stability, as shown by desorption tests.