One-electron oxidation of [CCOCC]–˙ in the gas phase forms stable and decomposing forms of CCCCO

Abstract

The radical anion [CCOCC]-* may be made in the source of a VG ZAB 2HF mass spectrometer by the reaction between F-(from SF6) and (CH3)3SiC[triple bond]COC[triple bond]CSi(CH3)3. Vertical (Franck-Condon) one-electron oxidation of [CCOCC]-* in the first collision cell produces both singlet and triplet CCOCC. A combination of experiment and molecular modelling (at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-31G* level of theory) gives data which are consistent with the CCOCC neutrals rearranging over small barriers to form singlet and triplet CCCCO in exothermic reactions. Both singlet and triplet CCCCO formed in this way have excess energy. Singlet CCCCO has sufficient excess energy to effect decomposition exclusively to CCC and CO. In contrast, some of the triplet CCCCO neutrals are stable, while others decompose to CCC and CO.

The one‐electron oxidation of [HCCOCC]− to form neutral HCCOCC, and the subsequent rearrangement of HCCOCC to form HCCCCO. An experimental and computational study

“…The rotational spectra of C n O (n = 2–9) have been detected in pyrolytic decomposition and pulsed discharge nozzle experiments 13–17. Some spectroscopic and/or structural details of CCCCO have been reported,10, 14, 17–22 and the neutral isomer CCOCC, formed from an anion in the gas phase, was found to undergo facile rearrangement to give stable and decomposing CCCCO 23…”