Modeling the Chemistry of Gaseous Cations Derived from Tricarbon Dioxide.

Abstract

Cations CpOq+ (p ≤ 7 with q = 1,2) and CpO3+ (p = 4-7) and corresponding neutrals are modeled by B3LYP/jun-cc-pVTZ to rationalize previous mass spectrometric observations of ion reactions with neutral C3O2. Modeling yields optimized potential energies, geometries, Mulliken spin populations, electric dipole moments, electron configurations, and thermochemical parameters. Lewis diagrams are derived. Mono- and dioxide cations typically have unbranched carbon chains, but trioxides are branched. The ions are most stable as spin doublets, but low-lying quartets are found for monoxides with even p. For trioxide ions, the quartets for p = 5,7 are lower-lying than for p = 4,6. For neutral mono- and dioxides resulting from possible electron transfer to the ions, triplets are more stable than singlets for even p. Neutral trioxides are most stable as triplets except C5O3 with a singlet slightly more stable. Singlet C4O3 and C6O3 are unstable with respect to CO loss. Charge transfer is likely only for CpO+ (p = 1-3) and CpO3+ (p = 4, 6). Monocarbon insertion by C3O2 is understood as two sequential CO losses without a hypothetical C6O4+• intermediate and is thermochemically favorable for all ions considered.