Reinvestigation of microwave spectrum of dimethyl ether and rs structures of analogous molecules

Niide, Yuzuru; Hayashi, Michiro

doi:10.1016/s0022-2852(03)00076-6

Cited by 37 publications

(52 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…But no explanation of this phenomenon seems to have been previously proposed. [5] It is the purpose of this section to give an explanation for the tilt of the methyl group and other CX 3 groups. Table 1 gives the experimental bond angles, bond lengths and interatomic distances for one of the simplest molecules to exhibit the methyl tilt, namely methanol CH 3 OH and Table 2 and Figure 1 the calculated data and its analysis in terms of interatomic distances.…”

Section: The Methyl Tiltmentioning

confidence: 99%

Ligand Close Packing, Molecular Compactness, the Methyl Tilt, Molecular Conformations, and a New Model for the Anomeric Effect

Gillespie

Robinson

Pilmé

2010

Chemistry A European J

View full text Add to dashboard Cite

All the atoms in a molecule attract each other until they reach their equilibrium positions at which point the repulsive forces between the atoms just balance the attractive forces and there are no resultant forces acting on any of the atoms in the molecule. Thus, we can consider that in the equilibrium geometry the atoms in a molecule are arranged as compactly as possible. This is the basis of the ligand close packing (LCP) model according to which three or four monatomic ligands X, such as F, Cl or O (formally =O or O(-)) pack as closely as possible around a small central atom such as a boron or carbon atom giving a truly close-packed equilateral triangular AX(3) molecule or a tetrahedral AX(4) molecules. Such monatomic ligands can, to a good approximation, be described as having a spherical shape with a single ligand radius r(X). In contrast, ligands with donor atoms with lone pairs such as the oxygen atom in an OX group have a less symmetrical electron density requiring two ligand radii, r(O(lp)) in the lone pair direction, and r(O(b)) in the bonding direction, where r(O(lp)) < r(O(b)) for an approximate description. On this basis we propose an explanation for the "methyl tilt", in methanol and many related molecules, and in conjunction with the concept of compactness, a model for explaining the relative energies of the conformations of molecules containing OH and OMe ligands, including molecules that exhibit the anomeric effect. We compare our model for the anomeric effect with the widely accepted "hyperconjugation" model. We also discuss the relationship between the concept of compactness and the concept of hardness.

show abstract

Section: The Methyl Tiltmentioning

confidence: 99%

Ligand Close Packing, Molecular Compactness, the Methyl Tilt, Molecular Conformations, and a New Model for the Anomeric Effect

Gillespie

Robinson

Pilmé

2010

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…For 12 CH 3 O 13 CH 3 , the existing data by Niide & Hayashi (2003) were substantially extended, and for ( 13 CH 3 ) 2 O the first rotational spectroscopic data are presented. Transitions involving energy levels up to J = 60 and K a = 25 (K a = 20, respectively) were analyzed and fitted to experimental uncertainty using the ERHAM effective rotational Hamiltonian for molecules with two large-amplitude motions.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…However, only very little is known about the 13 C-isotopologues of DME. Niide & Hayashi (2003) report some transition frequencies of DME-13 C 1 ( 12 CH 3 O 13 CH 3 ) below 50 GHz with maximum rotational quantum number J = 8. For DME-13 C 2 (( 13 CH 3 ) 2 O), so far no rotational spectroscopic data are available.…”

Section: Introductionmentioning

confidence: 89%

“…Energy levels including J = 60 and K a = 25 were accessed. Previously published frequencies from Niide & Hayashi (2003) were included in the analysis for transitions up to 34 GHz with an uncertainty of 50 kHz. A number of 24 transitions between 35 and 48 GHz were remeasured with our spectrometer, and the new frequencies with lower uncertainty were added to the dataset.…”

Section: Measured Laboratory Spectrum and Analysismentioning

confidence: 99%

See 1 more Smart Citation

Laboratory rotational spectra of the dimethyl ether¹³C-isotopologues up to 1.5 THz

Koerber

Bisschop

Endres

et al. 2013

A&A

View full text Add to dashboard Cite

Context. Dimethyl ether is found in high abundance in the interstellar medium. Owing to its strong and dense spectrum throughout the entire microwave and terahertz regime, it contributes to the spectral confusion in astronomical line surveys. The great sensitivity of new observatories like ALMA enhances the need for reliable spectroscopic data, especially for isotopic species of abundant molecules. In addition, the study of the interstellar 12 C/ 13 C isotopic ratio can be used as a tracer of the formation process of a molecular species, and thus it gives insight into the chemical evolution of the observed region. Aims. The interpretation of astronomical observations depends on the knowledge of accurate rest frequencies and intensities. The objective of this work is to provide spectroscopic data for the two 13 C-isotopologues of dimethyl ether in the vibrational ground state. Methods. High-resolution rotational-torsional spectra of 12 CH 3 O 13 CH 3 and ( 13 CH 3 ) 2 O have been measured in the laboratory covering frequencies up to 1.5 THz. The analysis is based on an effective rotational Hamiltonian for molecules with two large-amplitude motions.Results. Predictions of the complete ground state rotational spectrum of dimethyl ether-13 C 1 and -13 C 2 up to 2 THz are presented with accuracies better than 1 MHz. Based on the laboratory work, transitions of 12 CH 3 O 13 CH 3 dimethyl ether have been detected for the first time in a large submillimeter line survey of the high-mass star forming region G327.3-0.6 performed with the APEX telescope.

show abstract

“…This last analysis was performed by means of the ERHAM global analysis code [18]. Recently, three fundamental stretching bands were rotationally analyzed [19] and a new molecular structure was derived from MW measurement of some tens of lines (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) in gs for 17 isotopologues [20]. In 2009, Endres et al measured 1600 lines (39 GHz-2.1 THz) in gs for DME-h 6 and a global analysis was carried out with ERHAM [21].…”

Section: Introductionmentioning

confidence: 99%

Raman and infrared spectra of dimethyl ether 13C-isotopologue (CH3O13CH3) from a CCSD(T) potential energy surface

Carvajal

Álvarez‐Bajo

Senent

et al. 2012

Journal of Molecular Spectroscopy

View full text Add to dashboard Cite

So far, no experimental data of the infrared and Raman spectra of 13 C isotopologue of dimethyl ether are available. With the aim of providing some clues of its low-lying vibrational bands and with the hope of contributing in a next spectral analysis, a number of vibrational transition frequencies below 300 cm 1 of the infrared spectrum and around 400 cm 1 of the Raman spectrum have been predicted and their assignments were proposed. Calculations were carried out through an ab initio three dimensional potential energy surface based on a previously reported one for the most abundant dimethyl ether isotopologue (M. Villa et al., J. Phys. Chem. A 115 (2011) 13573). The potential function was vibrationally corrected and computed with a highly correlated CCSD(T) method involving the COC bending angle and the two large amplitude CH 3 internal rotation degrees of freedom. Also, the Hamiltonian parameters could represent a support for the spectral characterization of this species. Although the computed vibrational term values are expected to be very accurate, an empirical adjustment of the Hamiltonian has been performed with the purpose of anticipating some workable corrections to any possible divergence of the vibrational frequencies. Also, the symmetry breaking derived from the isotopic substitution of 13 C in the dimethyl ether was taken into account when the symmetrization procedure was applied.

show abstract

Reinvestigation of microwave spectrum of dimethyl ether and rs structures of analogous molecules

Cited by 37 publications

References 7 publications

Ligand Close Packing, Molecular Compactness, the Methyl Tilt, Molecular Conformations, and a New Model for the Anomeric Effect

Ligand Close Packing, Molecular Compactness, the Methyl Tilt, Molecular Conformations, and a New Model for the Anomeric Effect

Laboratory rotational spectra of the dimethyl ether¹³C-isotopologues up to 1.5 THz

Raman and infrared spectra of dimethyl ether 13C-isotopologue (CH3O13CH3) from a CCSD(T) potential energy surface

Contact Info

Product

Resources

About

Reinvestigation of microwave spectrum of dimethyl ether and rs structures of analogous molecules

Cited by 37 publications

References 7 publications

Ligand Close Packing, Molecular Compactness, the Methyl Tilt, Molecular Conformations, and a New Model for the Anomeric Effect

Ligand Close Packing, Molecular Compactness, the Methyl Tilt, Molecular Conformations, and a New Model for the Anomeric Effect

Laboratory rotational spectra of the dimethyl ether13C-isotopologues up to 1.5 THz

Raman and infrared spectra of dimethyl ether 13C-isotopologue (CH3O13CH3) from a CCSD(T) potential energy surface

Contact Info

Product

Resources

About

Laboratory rotational spectra of the dimethyl ether¹³C-isotopologues up to 1.5 THz