Activation of O₂, CO, and CO₂ by Pt⁺:  The Thermochemistry of PtO⁺

Reactions of Pt + with O 2, CO, and CO 2 have been studied as a function of kinetic energy using guided ion beam tandem mass spectrometry in order to elucidate the bond energy of the PtO + product. To further characterize the reaction of Pt + with CO 2, the reverse reaction of PtO + with CO, and the collision-induced dissociation of PtCO 2 + with Xe and Ar are also studied. In all cases, the kinetic energy dependences for these reactions show endothermic behavior except for PtO + + CO → Pt + + CO 2 and PtCO 2 + + Xe → PtXe + + CO 2 . Analyses of the endothermic reaction cross sections yield the 0 K bond dissociation energies (BDEs) in eV (kJ/mol) of D 0 (Pt + −O) = 3.26 ± 0.07 (315 ± 7), D 0 (Pt + −CO) = 2.28 ± 0.05 (220 ± 5), D 0 (Pt + −CO 2 ) = 0.62 ± 0.05 (60 ± 5), and D 0 (Pt + −C) = 5.46 ± 0.05 (527 ± 5), reasonably consistent with available theoretical values. Combining the PtO + BDE measured here with literature data also yields the ionization energy of PtO as 9.52 ± 0.25 eV. These data, along with ab initio calculations at the B3LYP/6-311+G(3df) level, enable the potential energy surfaces for the activation of CO 2 by Pt + to be mapped out in some detail. Evidence that PtCO 2 + has stable forms of both O−Pt + −CO and Pt + ·CO 2 are presented.