Experimental and theoretical evidence for the existence of a stable ketene dication in the gas phase

Abstract

The ketene dication, CH₂CO²⁺(1), is accessible buy charge stripping from C₂H₂O⁺˙ with Q_min= 18.6 ± 0.1 eV for C₂H₂O⁺˙→ C₂H₂O²⁺ which is in excellent agreement with the vertical ionization energy of 18.56 eV predicted by ab initio molecular orbital calculations (MP2/6-31G*//4-31G); from isodesmic substitution a heat of formation of 651 kcal mol^–1 is estimated for (1) which is also predicted by the ab initio calculations to correspond to the global minimum on the C₂H₂O²⁺ potential energy surface followed by the oxirene dication (2) having ΔH_f°= 678 kcal mol^–1(1 kcal = 4.184 kJ).