IR photodissociation spectroscopy of gas phase Pt+(CO)n (n = 4–6)

Platinum carbonyl complexes, Pt+(CO)n, are generated using laser vaporization and probed with infrared photodissociation spectroscopy in the C–O stretching region. No fragmentation is observed for the n = 1–3 complexes, indicative of their high binding energies. Pt+(CO)4 has enhanced abundance in cluster growth and is difficult to fragment, producing a noisy spectrum. The Pt+(CO)5,6 complexes fragment efficiently, producing the n = 4 ion. Their spectra, with carbonyl absorptions blue-shifted ∼10 cm−1 with respect to free CO, represent the resonances of Pt+(CO)4 detected by elimination of weakly bound external ligands. Pt+(CO)4 is indicated to have filled coordination and a high symmetry structure.