From Molecules with a Planar Tetracoordinate Carbon to an Astronomically Known C5H2 Carbene

Author(s)
Karton, Amir
Thimmakondu, Venkatesan S
Publication Date
2022-04-28
Abstract
<p>Ethynylcyclopropenylidene (<b>2</b>), an isomer of C<sub>5</sub>H<sub>2</sub>, is a known molecule in the laboratory and has recently been identified in Taurus Molecular Cloud-1 (TMC-1). Using high-level coupled-cluster methods up to the CCSDT(Q)/ CBS level of theory, it is shown that two isomers of C<sub>5</sub>H<sub>2</sub> with a planar tetracoordinate carbon (ptC) atom, (SP-4)-spiro[2.2]pent-1,4-dien-1,4-diyl (<b>11</b>) and (SP-4)-spiro[2.2]pent-1,4-dien-1,5-diyl (<b>13</b>), serve as the reactive intermediates for the formation of <b>2</b>. Here, a theoretical connection has been established between molecules containing ptC atoms (<b>11</b> and <b>13</b>) and a molecule (<b>2</b>) that is present nearly 430 light years away, thus providing evidence for the existence of ptC species in the interstellar medium. The reaction pathways connecting the transition states and the reactants and products have been confirmed by intrinsic reaction coordinate calculations at the CCSDT(Q)/CBS//B3LYP-D3BJ/cc-pVTZ level. While isomer <b>11</b> is non-polar (<i>μ</i> = 0), isomers <b>2</b> and <b>13</b> are polar, with dipole moment values of 3.52 and 5.17 Debye at the CCSD(T)/cc-pVTZ level. Therefore, <b>13</b> is also a suitable candidate for both laboratory and radioastronomical studies.</p>
Citation
The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory, 126(16), p. 2561-2568
ISSN
1520-5215
1089-5639
Link
Publisher
American Chemical Society
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International
Title
From Molecules with a Planar Tetracoordinate Carbon to an Astronomically Known C5H2 Carbene
Type of document
Journal Article
Entity Type
Publication

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