Thermochemistry and mechanisms of the Pt+ + SO2 reaction from guided ion beam tandem mass spectrometry and theory

The kinetic energy dependences of the reactions of Pt+ (D-2(5/2)) with SO2 were studied using a guided ion beam tandem mass spectrometer and theory. The observed cationic products are PtO+ and PtSO+, with small amounts of PtS+, all formed in endothermic reactions. Modeling the kinetic energy dependent product cross sections allows determination of the product bond dissociation energies (BDEs): D-0(Pt+-O) = 3.14 +/- 0.11 eV, D-0(Pt+-S) = 3.68 +/- 0.31 eV, and D-0(Pt+-SO) = 3.03 & PLUSMN; 0.12 eV. The oxide BDE agrees well with more precise literature values, whereas the latter two results are the first such measurements. Quantum mechanical calculations were performed for PtO+, PtS+, PtO2+, and PtSO+ at the B3LYP and coupled-cluster with single, double, and perturbative triple [CCSD(T)] levels of theory using the def2-XZVPPD (X = T, Q) and aug-cc-pVXZ (X = T, Q, 5) basis sets and complete basis set extrapolations. These theoretical BDEs agree well with the experimental values. After including empirical spin-orbit corrections, the product ground states are determined as PtO+ ((4)sigma(3/2)), PtS+ ((4)sigma(3/2)), PtO2+ ((2)sigma(+)(g)), and PtSO+ ((2)A'). Potential energy profiles including intermediates and transition states for each reaction were also calculated at the B3LYP/def2-TZVPPD level. Periodic trends in the thermochemistry of the group 9 metal chalcogenide cations are compared, and the formation of PtO+ from the Pt+ + SO2 reaction is compared with those from the Pt+ + O-2, CO2, CO, and NO reactions. Published under an exclusive license by AIP Publishing.