Neutral cumulene oxide CCCCO is accessible by one-electron oxidation of [CCCCO]⁻˙ in the gas phase

Abstract

Calculations at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-31G* level of theory indicate that doublet [CCCCO]-* is a stable species which should undergo collision-induced Franck-Condon vertical oxidation under neutralisation-reionisation conditions (-NR+) to produce both triplet CCCCO (ground state) and singlet CCCCO. Some of the neutral CCCCO species formed (particularly the triplet) should be stable for the microsecond duration of the NR experiment, whereas others will be energised (particularly the singlet) and should decompose to C3 and CO. The [CCCCO]-* radical anion has been formed in the ion source of the mass spectrometer by the reaction CH3OCH2C[triple bond]C-CO-CH(CH3)2 + O-* --> [CCCCO]-* + CH3O* + H2O + (CH3)2CH*. The -NR+ spectrum of [CCCCO]-* shows a recovery signal at m/z 64 corresponding to ionised CCCCO, together with a pronounced peak at m/z 36 (CCC+*) produced by ionisation of CCC (formed by the reaction CCCCO --> CCC + CO). The experimental observations are in agreement with the predictions of the theoretical study.

Some complexes containing carbon chains end-capped with tungsten or ruthenium groups and tricobalt carbonyl clusters

“…Partial deprotonation of the ruthenium reagent to form the alkynyl anion is followed by attack on [Co 3 (CCO)(CO) 9 ] + present in the reaction mixture. The species CCCCO has been obtained in gas-phase ion-molecule studies [18], but this is the first example of a metal complex stabilising this entity. The nearest congenor is the CCCO ligand present in Cr(CCCO)(CO) 5 [19].…”

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

“…1 2) at the CCSD(T)/augcc-pVDZ//B3LYP/6-31G* level of theory. 23 The majority of the [CCCCO] − • product anions formed in this way will therefore decompose in the ion source, others may be collision stabilised and not decompose.…”

“…14-17 Some spectroscopic and/or structural details of CCCCO have been reported. 11,15,18- 23 Neutral CCCCO has not been detected in circumstellar envelopes or molecular clouds, but it seems likely that it should be an interstellar molecule since the C 2 , C 3 and C 5 analogues have been so identified. The anion radical precursor of CCCCO may be formed in the ion source of a mass spectrometer by the reaction between O −• and CH 3 OCH 2 C≡C-CO-CH(CH 3 ) 2 , and Franck-Condon vertical one-electron oxidation of [CCCCO] − • gives stable triplet and decomposing singlet forms of CCCCO.…”

“…The anion radical precursor of CCCCO may be formed in the ion source of a mass spectrometer by the reaction between O −• and CH 3 OCH 2 C≡C-CO-CH(CH 3 ) 2 , and Franck-Condon vertical one-electron oxidation of [CCCCO] − • gives stable triplet and decomposing singlet forms of CCCCO. 23 In the course of that study, the structures and energies of the singlet and triplet forms of nine C 4 O isomers (that in principle, might be formed by isomerisation of CCCCO) were determined at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-31G* level of theory. These are summarised in Scheme 1.…”

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…”