Conversion of neutral C2COC2 to C4CO. potential interstellar molecules

Dua, Suresh, Blanksby, Stephen J., & Bowie, John H. (2000) Conversion of neutral C2COC2 to C4CO. potential interstellar molecules. International Journal of Mass Spectrometry, 195-196, pp. 45-54.

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Both [C4CO]−· and [C2COC2]−· are formed in the ion source of a VG ZAB 2HF mass spectrometer by the respective processes HO− + Me3Si–CC–CC–CO–CMe3 → [C4CO]−· + Me3SiOH + Me3C·, and Me3Si–CC–CO–CC–SiMe3 + SF6 + e → [C2COC2]−· + 2Me3SiF + SF4. The second synthetic pathway involves a double desilylation reaction similar to that first reported by Squires. The two radical anion isomers produce different and characteristic charge reversal spectra upon collisional activation. In contrast, following collision induced charge stripping, both radical anions produce neutral C4CO as evidenced by the identical neutralisation reionisation (−NR+) spectra. The exclusive rearrangement of C213COC2 to C413CO indicates that 12C–O bond formation is not involved in the reaction. Ab initio calculations (at the RCCSD(T)/aug-cc-pVDZ//B3LYP/6-31G∗ level of theory) have been used to investigate the reaction coordinates on the potential surfaces for both singlet and triplet rearrangements of neutral C2COC2. Singlet C2COC2 is less stable than singlet C4CO by 78.8 kcal mol−1 and requires only 8.5 kcal mol−1 of additional energy to effect conversion to C4CO by a rearrangement sequence involving three C–C ring opening/cyclisation steps.

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ID Code: 70669
Item Type: Journal Article
Refereed: Yes
Keywords: anions and neutrals, isomers at C5O, gas-phase reactivity, gaussian-basis sets, negative-ions, tricarbon, monoxide, triple excitations, mass-spectrometry, carbon monoxides, anions, shell, generation
DOI: 10.1016/s1387-3806(99)00188-8
ISSN: 1387-3806
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2000 Elsevier Science B.V.
Deposited On: 29 Apr 2014 04:18
Last Modified: 29 Apr 2014 04:18

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