The formation of the neutral isomers NCCCCO and CCC(O)CN in the gas phase from ionic precursors: a joint experimental and theoretical study

Abstract

The two neutral radicals NCCCCO and CCC(O)CN have been made by collision-induced vertical one-electron reduction and oxidation (respectively) of the charged species NCCCCO+ and - CCC(O)CN. The two charged precursors were prepared by the following reactions: (a) [NC-C≡C-CO-CH3]+. → NCCCO+ + CH3. and (b) (CH3)3Si-C≡C-CO-CN + F- → n -CCC(O)CN + (CH3)3SiF. Neutral NCCCCO is a stable species, but when energized decomposes by loss of CO to form the radical CCCN [process endothermic by 38.5 kcal mol-1: calculations at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-31G(d) level of theory]. Neutral CCC(O)CN is 46.8 kcal mol-1 more positive in energy than the isomer NCCCCO. When energized, CCC(O)CN decomposes by loss of NC to form CCCO (process endothermic by 28.1 kcal mol-1), but also undergoes a rearrangement process to produce NCCCCO, which is formed with excess energy and may decompose by loss of CO.