Tentative identification of C5N2 in rare gas matrices

Smith, Alice M.; Engel, C.; Thoma, A.; Schallmoser, Günter; Wurfel, Brent E.; Bondybey, V. E.

doi:10.1016/0301-0104(94)00096-4

Cited by 23 publications

(20 citation statements)

References 19 publications

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“…Emphasizing that most stable isomers of carbon‐based chains of the type considered in our paper are not invariably singlets is important because this was incorrectly claimed in some recent studies done in the astronomical/astrophysical community . Prior to the present extensive study, a series of authors drew attention on the fact that triplet isomers of carbon‐based chains are more stable than singlet isomers: HC

_{2 k^{+} 1}

H, C 2 k , HC 4 N, NC 5 N, C 2 k O, C 2, 4 S, and HC 6 N …”

Section: Resultsmentioning

confidence: 88%

“…Emphasizing that most stable isomers of carbon-based chains of the type considered in our paper are not invariably singlets is important because this was incorrectly claimed in some recent studies done in the astronomical/astrophysical community. 22,24 Prior to the present extensive study, a series of authors drew attention on the fact that triplet isomers of carbon-based chains are more stable than singlet isomers: HC 2k +1 H, 25,64 C 2k , 25,65 HC 4 N, 66-69 NC 5 N, 70 C 2k O, 71 C 2,4 S,, 72 and HC 6 N. 73 Last but not least, from a computational perspective, the present results are important because they emphasize that electron correlations in carbon-based chains are unusually strong. The analysis of Section 3.9 indicated that the "standard gold" CCSD(T) quantum chemical approach may not be sufficiently accurate to quantify these strong electron correlations.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Alternation of Singlet and Triplet States in Carbon‐Based Chain Molecules and Its Astrochemical Implications: Results of an Extensive Theoretical Study

Bâldea

2019

Advcd Theory and Sims

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A variety of homologous carbon chains (HC n H, HC n N, C n S, C n O, and OC n O) are found to exhibit an appealing even-odd effect. Chains containing a number of carbon atoms of a certain parity possess singlet ground states, while members of opposite parity have triplet ground states. From a general perspective, it is important that this even-odd effect confounds straightforward chemical intuition. Whether the most stable form is a triplet or a singlet is neither simply related to the fact that the species in question is a "normal" (closed-shell, nonradical) molecule nor a (di)radical or to the (e.g., cumulene-type) C─C bond succession across the chain. From a computational perspective, the present results are important also because they demonstrate that electron correlations in carbon-based chains are extremely strong. Whether the "gold-standard" CCSD(T) (coupled-cluster expansions with single and double excitations and triple excitations corrections) framework suffices to describe such strongly correlated systems remains an open question that calls for further clarification. Most importantly for astrochemistry, the present results may explain why certain members are not astronomically observed although larger members of the same homologous series are detected; the missing species are exactly those for which the present calculations predict triplet ground states.

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_{2 k^{+} 1}

H, C 2 k , HC 4 N, NC 5 N, C 2 k O, C 2, 4 S, and HC 6 N …”

Section: Resultsmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Alternation of Singlet and Triplet States in Carbon‐Based Chain Molecules and Its Astrochemical Implications: Results of an Extensive Theoretical Study

Bâldea

2019

Advcd Theory and Sims

View full text Add to dashboard Cite

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“…In our earlier study of photoisomerization of the C 4 N 2 compound, 30 we have found that the iso-nitrile isomer peaks are a couple of orders of magnitude more intense than those of the nitrile, and these intensity differences were also predicted by theoretical computations. 31 The assignment of the observed product absorptions to the isonitrile ions, and the absence of observable absorptions of the lower energy nitrile cations could perhaps still be rationalized if similar differences in intensities also occured in the H(D͒C 3 N ϩ species.…”

Section: E Deuteration Experiments: DC 3 N ¿mentioning

confidence: 53%

“…3, and it contains besides the mass 38 also the interesting mass 88 fragment, C 5 N 2 ϩ , whose neutral counterpart was the subject of several separate investigations. [20][21][22] When 100-150 pA of mass 38 was deposited overnight for nearly 15 hours together with neon matrix gas, and with an approximately threefold higher electron current, a very simple Fourier transform ͑FT͒-IR spectrum resulted. Several weak, rather broad bands were clearly attributable to the neutral TCNE precursor, which, in view of the very long deposition time, reached the sample substrate.…”

Section: The Cnc ¿ Cationmentioning

confidence: 99%

Vibrational spectroscopy of matrix-isolated, mass-selected cyanoacetylene cations

Smith-Gicklhorn

Lorenz

Kołos

et al. 2001

The Journal of Chemical Physics

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Recent infrared spectroscopic results from a new setup for the deposition of mass-selected ions in neon matrices are presented. The strong infrared signal observed for the asymmetric stretch of CNC ϩ and the appearance of the corresponding band for 13 CNC ϩ in its natural isotopic abundance, demonstrates the sensitivity and usefulness of the apparatus. Evidence of a combination band of CNC ϩ involving the low-frequency bend is also obtained. Using this setup, the infrared spectra of the cyanoacetylenic cations, H͑D͒C 3 N ϩ , and C 4 N 2 ϩ are observed for the first time. The assignment of the stretching vibrations of these linear cations are well-supported by density-functional calculations.

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“…13 In the case of NC 5 N an electronic absorption spectrum in a neon matrix 42 and computational data 43 are available, but gas-phase spectra have not been recorded. 13 In the case of NC 5 N an electronic absorption spectrum in a neon matrix 42 and computational data 43 are available, but gas-phase spectra have not been recorded.…”

Section: Isoelectronic Species and Line Broadeningmentioning

confidence: 99%

The A 3Σ−–X 3Σ− electronic transition of HC6N

Vaizert¹,

Motylewski²,

Wyss³

et al. 2001

The Journal of Chemical Physics

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A combined matrix and gas phase study is presented to identify the A 3 ⌺ Ϫ -X 3 ⌺ Ϫ electronic transition of the linear triplet isomer of HC 6 N and isotopic derivative DC 6 N. Absorption spectra have been observed in a 6 K neon matrix after mass selective deposition and in the gas phase by cavity ring down spectroscopy through a supersonic planar plasma. The band origin of the 0 0 0 A 3 ⌺ Ϫ -X 3 ⌺ Ϫ electronic transition of HC 6 N is determined to be at 21 208.60͑5͒ cm Ϫ1 , shifted ϳ30 cm Ϫ1 to the blue of the neon matrix value. Rotational analysis indicates that the chain is slightly stretched on electronic excitation, yielding B 0 Јϭ0.027 92(5) cm Ϫ1 . Transitions to vibrationally excited levels in the upper A 3 ⌺ Ϫ state are observed as well. The results are compared with a rotationally resolved spectrum of the 0 0 0 A 3 ⌺ u Ϫ -X 3 ⌺ g Ϫ electronic transition of the isoelectronic HC 7 H species.

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Tentative identification of C5N2 in rare gas matrices

Cited by 23 publications

References 19 publications

Alternation of Singlet and Triplet States in Carbon‐Based Chain Molecules and Its Astrochemical Implications: Results of an Extensive Theoretical Study

Alternation of Singlet and Triplet States in Carbon‐Based Chain Molecules and Its Astrochemical Implications: Results of an Extensive Theoretical Study

Vibrational spectroscopy of matrix-isolated, mass-selected cyanoacetylene cations

The A 3Σ−–X 3Σ− electronic transition of HC6N

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