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Interstellar Space (interstellar + space)
Selected AbstractsThioxoethenylidene C2S: A Matrix - Spectroscopic StudyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2004Günther Maier Abstract Thioxoethenylidene C2S (5), known for its high abundance in interstellar space, has been generated by irradiation of C3S2 (4) and C3OS (6) in an argon matrix at 10 K. Its structural elucidation is based on comparison of the experimental and calculated IR and UV spectra. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Possible molecular hydrogen formation mediated by the radical cations of anthracene and pyreneJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 12 2003Mutsumi Hirama Abstract Hydrogen molecules cannot be formed readily by the association of gaseous hydrogen atoms. Possible H2 formation mediated by the radical cations of typical polycyclic aromatic hydrocarbons (PAHs), anthracene and pyrene, was studied at the B3LYP/6-31G** level of theory. We presumed that H2 is formed by way of two elementary reactions: the addition of an H atom to a PAH molecular cation, and the H abstraction from the resulting monohydro-PAH cation (i.e., arenium ion) by a second H atom to yield H2. The first reaction takes place without any activation energy. The second reaction is also predicted to proceed along almost barrierless pathways, although it is far from being a typical ion,molecule reaction. There is a possibility that these reactions might constitute one of the mechanisms for H2 formation in extremely cold interstellar space. Deuterium enrichment in PAH cations is possibly accompanied by such H2 formation because deuteration lowers the energies of polyatomic PAH cations appreciably. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1378,1382, 2003 [source] Ribbon structure reveals influence of interstellar spaceASTRONOMY & GEOPHYSICS, Issue 6 2009Article first published online: 23 NOV 200 No abstract is available for this article. [source] Cyanomethylidyne: A Reactive Carbyne RadicalCHEMPHYSCHEM, Issue 3 2006Jian Wang Abstract The cyanomethylidyne radical (CCN) has been a long-standing subject of extensive structural and spectroscopic studies. However, its chemical reactivity has received rather little attention. Recently, we studied the reaction of CCN with the simplest alkane, CH4, which follows a mechanism of carbyne insertion,dissociation rather than that of direct H abstraction proposed by a recent experimental study. However, we are aware that alkanes like CH4 bear no electron lone pairs and thus are not ideal diagnostic molecules for distinguishing between the carbyne-insertion and H-abstraction mechanisms. Hence, we chose a series of ,-bonded molecules HX (X=OH, NH2, and F) which bear electron lone pairs and are better diagnostics for carbyne-insertion behavior. The new results at the CCSD(T)/6-311+G(2df,p)//B3LYP/6-311G(d,p)+ZPVE, CCSD(T)/aug-cc-pVTZ//B3LYP/6-311G(d,p)+ZPVE, G2M(CC1), and MC-QCISD//B3LYP/6-31G(d)+ZPVE levels definitively confirm the carbyne-insertion behavior of the CCN radical towards HX. In addition, we make the first attempt to understand the reactivity of the CCN radical toward ,-bonded molecules, using the CCN+C2H2 model reaction. This reaction involves carbenoid addition to the CC bond without a potential-energy barrier to form a C3 three-membered cyclic intermediate followed by H extrusion. Therefore, the reactions of CCN with both ,- and ,-bonded molecules conclusively show that CCN is a reactive carbyne radical and may be more reactive than the well-known CN radical. Future experimental studies, especially on product characterization, are strongly desired to test our proposed carbyne mechanism. The studied reactions of CCN with CH4,, NH3,, H2O, and C2H2 could be of interest to combustion science and astrophysics, and they could provide efficient routes to form novel cyano-containing molecules in interstellar space. [source] | ||||||||||