Polycarbonyl species in Pt/H-ZSM-5: FTIR spectroscopic study of 12CO-13CO co-adsorption

In this work, we report on the formation of several non-classical carbonyls of platinum produced after CO adsorption on Pt/H-ZSM-5. These are: (i) two kinds of Pt3+(CO)2 dicarbonyls (νs at 2212 cm−1 and νas at 2176 cm−1; νs at 2196 cm−1 and νas at ca. 2155 cm−1), which are decomposed without producing monocarbonyls; (ii) Pt2+-CO (2150 cm−1), which form dicarbonyls at high CO coverages; (iii) Pt+(CO)3 complexes (2161, 2153 and 2110 cm−1) which easily lose one CO ligand even at room temperature, being thus converted to Pt+(CO)2 (2122 and 2092 cm−1). The latter are thermally decomposed without producing monocarbonyls. In addition, carbonyls of metallic platinum have been found.