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Title

Theoretical Study of Interstellar Hydroxylamine Chemistry: Protonation and Proton Transfer Mediated by H3+

Authors
Gilardoni, François
Published in Chemical Physics. 1999, vol. 244, no. 2-3, p. 163-174
Abstract Protonated species are known to play a key role for ion-molecule reactions in gas phase interstellar chemistry. As hydroxylamine (H2NOH) has never been observed as an interstellar molecule, a detailed theoretical investigation of the protonation of H2NOH is carried out at high level of quantum chemical theories (CCSD(T) and DFT-B3LYP). As protonation may occur directly by reaction with H+ or mediated by H3+, both processes are investigated on the nitrogen and the oxygen sites of hydroxylamine. The present results show that the N-protonated form is more stable than the O-protonated one and that the protonation initiated by H3+ is by far less exothermic than the other one. A particular attention is paid to the intramolecular rearrangement leading from H3NOH+ to H2NOH2+ which involves a highly energetic transition state exhibiting proton bridged between N and O sites. As this barrier is too high to be easily overcome in the interstellar medium, an alternative process mediated by H2 and involving a bridged H3+ as a transition state is considered. The calculations show that the corresponding activation energy is significantly lowered.
Keywords Interstellar hydroxylamine chemistryProtonationProton transfer
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Research group Groupe Weber
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BOULET, Pascal et al. Theoretical Study of Interstellar Hydroxylamine Chemistry: Protonation and Proton Transfer Mediated by H3+. In: Chemical Physics, 1999, vol. 244, n° 2-3, p. 163-174. https://archive-ouverte.unige.ch/unige:2743

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Deposited on : 2009-09-21

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