Formation of two isomeric C3HO radicals from charged precursors in the gas phase. Potential interstellar molecules

Peppe, S., Blanksby, Stephen J., Dua, S., & Bowie, J. H. (2000) Formation of two isomeric C3HO radicals from charged precursors in the gas phase. Potential interstellar molecules. Journal of Physical Chemistry A, 104(24), pp. 5817-5824.

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Theoretical calculations of the C3HO potential surface at the CCSD(T)/aug-cc-pVDu/B3LYP/6-31G* level indicate that the three radicals HCCCO, CCCHO, and (cyclo-C3H)=O are stable, with HCCCO being the most stable of the three. A fourth isomer, CCHCO, is unstable with respect to cyclization to (cyclo-C3H)=O. Two isomers have been prepared by neutralization of charged precursors, formed as follows: (i) HCCCO, by HC drop C-C(O)-O+(H)(Me) --> HC3O+ + MeOH, and (ii) C2CHO, by (a) Me3SiC drop C-CHO + HO- --> C- drop C-CHO + Me3SiOH and (b) C- drop C-CH(OH)-C drop CH --> C- drop C-CHO + C2H2. A comparison of the CR and -NR+ spectra of -C2CHO indicate that C2CHO is (partially) rearranging to an isomer that shows significant formation of CO.(+) in the -NR+ spectrum of the anion. Ab initio calculations indicate that HCCCO is the product of the isomerism and that a proportion of these isomerized neutrals dissociate to CO and C2H. The neutral HCCCO may be formed by (i) synchronous rearrangement of C2CHO and/or (ii) stepwise rearrangement of C2CHO through (cyclo-C3H)=O. The second of these processes should have the higher rate, as it has the lower barrier in the rate-determining step and the higher Arrhenius pre-exponential A factor.

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ID Code: 71513
Item Type: Journal Article
Refereed: Yes
Keywords: carbon-chain molecules, gaussian-basis sets, tricarbon monoxide, ab-initio, mass-spectrometry, negative-ions, anions, clouds, shell, reactivity
DOI: 10.1021/jp994229g
ISSN: 1520-5215 (online) 1089-5639 (print)
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2000 American Chemical Society
Deposited On: 13 May 2014 04:33
Last Modified: 13 May 2014 04:33

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