Broadband microwave spectroscopy of cyclopentylsilane and 1,1,1-trifluorocyclopentylsilane

Licaj, Lucas; Moon, Nicole; Grubbs, Garry S.; Guirgis, Gamil A.; Seifert, Nathan A.

doi:10.1016/j.jms.2022.111698

Cited by 3 publications

(1 citation statement)

References 34 publications

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“…In recent years, the authors have undertaken rotational spectroscopy studies that investigate the structural differences in substituting a carbon with a silicon atom. − Studies of these systems have led to interesting physiochemical results like ring-puckering motions, planar vs nonplanar ring structures, or C 2 symmetry in straight-chain alkane species where one may expect C 2 v . In some of these systems, the potential energy surfaces of the ring-puckering motion may be flatter at the base through the puckering coordinate than the carbon analogues or may result in a double well.…”

Section: Introductionmentioning

confidence: 99%

Rotational Spectrum and Ring Structures of Silacyclohex-2-ene and 1,1-Difluorosilacyclohex-2-ene

Moon,

Duerden,

McFadden

et al. 2023

J. Phys. Chem. A

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Silacyclohex-2-ene and 1,1-difluorosilacyclohex-2-ene have been synthesized, and the chirped-pulse, Fourier-transform microwave spectra of each have been observed and analyzed from 4.9 to 23.1 GHz. Quantum chemical calculations have been performed at the B3LYP-D3BJ/Def2TZVP level of theory and predict μ a to be the largest dipole moment component with a significantly larger value in this component for 1,1-difluorosilacyclohex-2-ene. In accordance with this prediction, the spectra were predominantly a-type with the observation of a few b-and c-type transitions. The signalto-noise ratio was adequate in both spectra to observe 29 Si, 30 Si, and all singly substituted 13 C isotopologues in natural abundance. All spectra have been fit to a semirigid rotational Hamiltonian and are presented. Analysis of the physical meaning of the fitted parameters is explored and determined to hold for the rotational constants while being more empirical for the centrifugal distortion terms. Experimental structures of both molecules indicate that the quantum chemically calculated structures for the atoms in the ring are a very close depiction of the experimentally determined structures. The structures of each molecule are compared to similar molecules for context, where it is shown that both molecules possess a similar "half-chair" conformation to that of the all-carbon analogue, cyclohexene.

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Section: Introductionmentioning

confidence: 99%

Rotational Spectrum and Ring Structures of Silacyclohex-2-ene and 1,1-Difluorosilacyclohex-2-ene

Moon,

Duerden,

McFadden

et al. 2023

J. Phys. Chem. A

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The microwave spectrum of the low energy conformers of 1-ethylsilacyclopentane

Glenn,

Isert,

Bethke

et al. 2024

Journal of Molecular Spectroscopy

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Rotational spectrum, structure, and quadrupole coupling of cyclopropylchloromethyldifluorosilane

Davies,

Hanna,

Lutas

et al. 2024

The Journal of Chemical Physics

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Cyclopropylchloromethyldifluorosilane, c-C3H5SiF2CH2Cl, has been synthesized, and its rotational spectrum has been recorded by chirped-pulse Fourier transform microwave spectroscopy. The spectral analysis of several isotopologues indicates the presence of two distinct conformations in the free-jet expansion, which are interconvertible through a rotation of the chloromethyl group. A partial substitution structure is presented for the lower energy conformation and is compared to the equilibrium structure obtained from quantum chemical calculations. Additionally, the presence of the chlorine nucleus leads to the rotational transitions splitting into multiple hyperfine components and χaa, a measure of the electric field gradient along the a axis, is unusually small at merely +0.1393(73) MHz. Various common ab initio and density functional theory methods fail to predict good quadrupole coupling constants (in the principal axis system) that adequately reproduce the observed hyperfine splitting, although diagonalizing the quadrupole coupling tensor from the principal axis system into a nucleus-centered axis system reveals that, overall, these methods calculate reasonably the electric field gradient about the chlorine nucleus. Finally, a total of nine electric dipole forbidden, quadrupole allowed transitions are observed in the rotational spectra of the parent species of the higher energy conformation and the 37Cl isotopologue of the lower energy conformation. These include those of x-type (no change in parity of Ka or Kc), which, to our knowledge, is the first time such transitions have been observed in a chlorine-containing molecule.

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Broadband microwave spectroscopy of cyclopentylsilane and 1,1,1-trifluorocyclopentylsilane

Cited by 3 publications

References 34 publications

Rotational Spectrum and Ring Structures of Silacyclohex-2-ene and 1,1-Difluorosilacyclohex-2-ene

Rotational Spectrum and Ring Structures of Silacyclohex-2-ene and 1,1-Difluorosilacyclohex-2-ene

The microwave spectrum of the low energy conformers of 1-ethylsilacyclopentane

Rotational spectrum, structure, and quadrupole coupling of cyclopropylchloromethyldifluorosilane

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