Two Isomers of Protonated Isocyanic Acid: Evidence for an Ion鈥揗olecule Pathway for HNCO 鈫?HOCN Isomerization

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• 作者：Valerio Lattanzi ; Sven Thorwirth ; Carl A. Gottlieb ; Michael C. McCarthy
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2012
• 出版时间：December 6, 2012
• 年：2012
• 卷：3
• 期：23
• 页码：3420-3424
• 全文大小：259K
• 年卷期：v.3,no.23(December 6, 2012)
• ISSN：1948-7185

文摘

Ion鈥搈olecule reactions are thought to play a crucial role in the formation of metastable isomers, but relatively few protonated intermediates beyond HNCH⁺ have been characterized at high spectral resolution. We present here laboratory measurements of the rotational spectra of protonated isocyanic acid in two isomeric forms, the ground state H₂NCO⁺ with C_2v symmetry and a low-lying bent chain HNCOH⁺, guided by coupled cluster calculations of their molecular structure. Somewhat surprisingly, HNCOH⁺ is found to be more abundant than H₂NCO⁺, even though this metastable isomer is calculated to lie approximately 15鈥?0 kcal/mol higher in energy. In the same way that HCNH⁺ serves as a key intermediate in ion鈥搈olecule reactions that form HNC via dissociative electron recombination in cold dense interstellar molecular clouds, HNCOH⁺ may play an analogous role in the conversion of HNCO to HOCN.

Keywords:

rotational spectroscopy; quantum-chemical calculations; astronomy&qsSearchArea=searchText">radio astronomy; molecular structure; bonding