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Wehres, Nadine; Zhao, Dongfeng; Ubachs, Wim; Linnartz, H.

doi:10.1016/j.cplett.2010.08.006

Cited by 8 publications

(3 citation statements)

References 23 publications

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“…However, one of the isomers of SiC 3 , which contains a transannular C–C bond (rhomboidal geometry) has been confirmed in the evolved carbon star, IRC + 10216 based on laboratory rest frequencies . Within C 5 H 2 elemental composition, the elusive aromatic carbene, 2-methylenebicyclo[1.1.0]but-1(3)-en-4-ylidene ( 9 ; see Figure ), also contains a transannular C–C bond but less attention has been paid to this molecule. − Of note, for the confirmation of four C n H 2 carbenes in nonterrestrial environments, − identification of the same in laboratories (terrestrial environments) is a crucial factor. ,,− Therefore, considering the astrochemical relevance, available laboratory astrophysics data, and enhancing our understanding of structure and bonding of various C n H 2 isomers, where, n = 2, 3, ,,,,− 4, ,,− 5, − 6, ,,− 7, ,,− 8, ,,, 9, ,,,,…”

Section: Introductionmentioning

confidence: 99%

Theoretical Studies of Two Key Low-Lying Carbenes of C₅H₂Missing in the Laboratory

et al. 2019

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The equilibrium geometries and spectroscopic properties of two key singlet carbenes, buta-1,3-diynylcarbene (6) and 2-methylenebicyclo[1.1.0]but-1(3)-en-4-ylidene (9), which have not been experimentally observed to date, are investigated using high-level coupled-cluster (CC) methods. The current theoretical study necessitates new experimental data on C 5 H 2 isomers considering the relevance of these molecules to interstellar chemistry. Bent-pentadiynylidene (4) has been missing in the laboratory and the prime focus of our earlier theoretical work. The present theoretical study indicates that isomers 6 and 9 are also viable experimental targets. Apart from ethynylcyclopropenylidene (2), pentatetraenylidene (3), ethynylpropadienylidene (5), and 3-(didehydrovinylidene)cyclopropene ( 8), which are identified by Fourier transform microwave spectroscopy, the dipole moments of elusive 4, 6, and 9 are also non-zero (µ = 0). The relative energies of these isomers, calculated at the CCSDT(Q)/CBS level of theory, with respect to linear triplet pentadiynylidene (1) reveal that they all lie within 25.1 kcal mol −1 . Therefore, geometric, energetic, aromatic, and spectroscopic parameters are reported here, which may assist the efforts of molecular spectroscopists in the future. Anharmonic vibrational calculations on isomers 6 and 9 indicate that the former is loosely bound and would be challenging to be detected experimentally. Among the undetected carbenes, 9 may be considered as a potential target molecule considering its higher polarity and aromatic nature.

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Section: Introductionmentioning

confidence: 99%

Theoretical Studies of Two Key Low-Lying Carbenes of C₅H₂Missing in the Laboratory

et al. 2019

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“…Typical ring down events are of the order of 60 µs. The dye laser has a bandwidth of ∼0.07 cm −1 and this can be further improved to ∼0.035 cm −1 using the second order diffraction of the Littrow grating in the oscillator [11,12]. An absolute frequency calibration is achieved with a precision better than 0.02 cm −1 by simultaneously recording an I 2 reference spectrum.…”

Section: Methodsmentioning

confidence: 99%

Spin-orbit Splitting and Lifetime Broadening in theA2Δ Electronic State ofl-C5H

Haddad

Zhao

Linnartz

et al. 2012

Chinese Journal of Chemical Physics

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Optical absorption bands at ∼18772 and ∼18807 cm −1 , previously assigned to A 2 ∆-X 2 Π electronic origin band transitions of the linear carbon-chain radicals C 5 H and C 5 D, respectively, have been reinvestigated. The spectra have been recorded in direct absorption applying cavity ring-down spectroscopy to a supersonically expanding acetylene/helium plasma. The improved spectra allow deducing a l-C 5 H upper state spin-orbit coupling constant A =−0.7(3) cm −1 and a A 2 ∆ lifetime of (1.6±0.3) ps.

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“…Previous studies have shown that this basis set predicts rotational constants of conjugated carbon chains with reasonably high precision. 28,33,35 The resulting molecular structures are subsequently employed to predict the vertical electronic transition energy by time-dependent density functional response theory (TD-DFT/B3LYP) 36 employing a 6-311++G(2d, p) basis set. Complete active space multiconfiguration SCF calculations 37 with seven electrons and eight orbitals in the active space (CASSCF(7, 8)) are performed for the bent HC 4 CHC 2n H (n = 1-4) chains to characterize the role of the active molecular orbitals upon electronic excitation.…”

Section: B Density Functional Theory Calculationsmentioning

confidence: 99%

The electronic spectrum of the C s-C11H3 radical

Zhao

Linnartz

Ubachs

2012

The Journal of Chemical Physics

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The electronic gas-phase absorption spectrum of the bent carbon-chain radical, HC(4)CHC(6)H with C(s) symmetry, is recorded in the 595 nm region by cavity ring-down spectroscopy through an expanding hydrogen plasma. An unambiguous spectroscopic identification becomes possible from a systematic deuterium labeling experiment. A comparison of the results with recently reported spectra of the nonlinear HC(4)CHC(4)H and HC(4)C(C(2)H)C(4)H radicals with C(2v) symmetry provides a more comprehensive understanding of the molecular behavior of π-conjugated bent carbon-chain systems upon electronic excitation. We find that the electronic excitation in the bent carbon-chain HC(4)CHC(2n)H (n = 1-4) series exhibits a similar trend as in the linear HC(2n+1)H (n = 3-6) series, shifting optical absorptions towards longer wavelengths for increasing overall bent chain lengths. The π-conjugation in bent HC(4)CHC(2n)H (n = 1-4) chains is found to be generally smaller than in the linear HC(2n+1)H (n = 3-6) case for equivalent numbers of C-atoms. The addition of an electron-donating group to the bent chain causes a slight decrease of the effective conjugation.

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Rotationally resolvedA3Σu-–

Cited by 8 publications

References 23 publications

Theoretical Studies of Two Key Low-Lying Carbenes of C₅H₂Missing in the Laboratory

Theoretical Studies of Two Key Low-Lying Carbenes of C₅H₂Missing in the Laboratory

Spin-orbit Splitting and Lifetime Broadening in theA2Δ Electronic State ofl-C5H

The electronic spectrum of the C s-C11H3 radical

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Rotationally resolvedA3Σu-–

Cited by 8 publications

References 23 publications

Theoretical Studies of Two Key Low-Lying Carbenes of C5H2Missing in the Laboratory

Theoretical Studies of Two Key Low-Lying Carbenes of C5H2Missing in the Laboratory

Spin-orbit Splitting and Lifetime Broadening in theA2Δ Electronic State ofl-C5H

The electronic spectrum of the C s-C11H3 radical

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Theoretical Studies of Two Key Low-Lying Carbenes of C₅H₂Missing in the Laboratory

Theoretical Studies of Two Key Low-Lying Carbenes of C₅H₂Missing in the Laboratory