Vibrational spectra and structure of (SiH3)2CH2 and (SiD3)2CH2

McKean, D.C.; Davidson, G.; Woodward, L. A.

doi:10.1016/0584-8539(70)80122-2

Cited by 25 publications

(28 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These two A 2 vibrations are calculated to have the weakest infrared intensities among the fundamentals for the four molecules and thus were difficult to assign without the DFT calculations. Several other studies – have employed DFT calculations to predict vibrational frequencies and to compare them with previous experimental results for some noncyclic silicon-containing molecules including dimethylsilane, , trimethylsilane, , disilylmethane, , and ethylsilane . These studies utilized the calculated frequencies to reinvestigate some of the uncertain aspects of the vibrational spectra recorded many years earlier, but none of these studies noted why such a discrepancy between the experimental and calculated frequencies for these CH 2 out-of-phase modes should occur. – Nevertheless, one conclusion drawn from all these studies as well as our own is that the presence of a silicon atom in the structure of a molecule does not adversely affect the accuracy of the vibrational frequencies calculated by the DFT method.…”

Section: Vibrational Assignmentsmentioning

confidence: 99%

“…Several other studies – have employed DFT calculations to predict vibrational frequencies and to compare them with previous experimental results for some noncyclic silicon-containing molecules including dimethylsilane, , trimethylsilane, , disilylmethane, , and ethylsilane . These studies utilized the calculated frequencies to reinvestigate some of the uncertain aspects of the vibrational spectra recorded many years earlier, but none of these studies noted why such a discrepancy between the experimental and calculated frequencies for these CH 2 out-of-phase modes should occur. – Nevertheless, one conclusion drawn from all these studies as well as our own is that the presence of a silicon atom in the structure of a molecule does not adversely affect the accuracy of the vibrational frequencies calculated by the DFT method. Moreover, for disilylmethane (CH 3 SiH 2 CH 3 ), the CH 2 twisting vibration was previously predicted with the B3LYP/6-311G(d,p) level of theory to be at 1043 cm −1 , which is at a somewhat lower value than had been assigned before (1101 cm −1 ).…”

Section: Vibrational Assignmentsmentioning

confidence: 99%

See 1 more Smart Citation

Structure, Vibrational Spectra, and DFT and ab Initio Calculations of Silacyclobutanes

Al‐Saadi

Laane

2008

Organometallics

View full text Add to dashboard Cite

Ab initio calculations have been carried out for silacyclobutane (SCB) and its 1,1-difluoro and 1,1-dichloro derivatives in order to compute the structures and dihedral angles of puckering for these molecules. For SCB the calculated dihedral angle of 35° agrees nicely with the 36° value obtained from far-infrared work. The calculated angles of 29° and 31° for the fluoro and chloro derivatives, respectively, can be compared to electron diffraction results of 25° and 26°. The zero-point-corrected barriers calculated using the MP2/cc-pVTZ level of theory were 523 (as compared to 440 cm−1 experimental), 186, and 433 cm−1 for SCB and its fluoro and chloro derivatives, respectively. Calculated structural changes in the dihalo derivatives can be ascribed to the high electronegativity of the halogen atoms. High-level DFT computations were also carried out in order to calculate the infrared and Raman spectra of these three molecules as well as the SCB 1,1-d 2 isotopomer. The agreement between experimental and calculated spectra is remarkably good for all four molecules. The predicted frequencies and intensities were utilized to reassign several of the weaker spectral bands and also to characterize the 1130 cm−1 signature band present in the infrared spectra of all silacyclobutanes. This arises from the α-CH2 in-phase wagging vibration, which is very much affected by the neighboring silicon atom. The DFT calculations also demonstrated that two of the wagging and twisting motions of the CH2 group next to the silicon atom have frequencies much lower than in typical organic molecules. This work also provides frequency ranges that can be expected for the six vibrations of SiX2 groups (X = H, D, F, Cl) in organosilanes.

show abstract

Section: Vibrational Assignmentsmentioning

confidence: 99%

Section: Vibrational Assignmentsmentioning

confidence: 99%

Structure, Vibrational Spectra, and DFT and ab Initio Calculations of Silacyclobutanes

Al‐Saadi

Laane

2008

Organometallics

View full text Add to dashboard Cite

show abstract

“… a Also tabulated are the spectral frequencies of surface CH 2 species obtained after annealing the Me 3 Al-exposed GaAs(100) surface to 350 °C (Figure ). The assignments are made by comparison with infrared studies of Me 3 Al 28 and SiH 3 CH 2 SiH 3 …”

Section: Resultsmentioning

confidence: 99%

“…The appearance of this mode is also accompanied by a new feature at 865 cm -1 and a simultaneous decrease in the frequency of the band in the C−H stretching region from 2937 to 2890 cm -1 . The new bands are associated with the formation of a surface CH 2 species and are characterized by vibrational modes at 865 cm -1 (ρ(CH 2 )), 1340 cm -1 (δ(CH 2 )), and 2890 cm -1 (ν(CH 2 )) (Table ). ,− Further heating to temperatures in excess of 450 °C leads to a decrease in the intensity of all the adsorbate vibrational bands, and by 600 °C the decomposition of Me 3 Al is essentially complete.…”

Section: Resultsmentioning

confidence: 99%

“…The new bands are associated with the formation of a surface CH 2 species and are characterized by vibrational modes at 865 cm -1 (F-(CH 2 )), 1340 cm -1 (δ(CH 2 )), and 2890 cm -1 (ν(CH 2 )) (Table 1). 27,[30][31][32][33] Further heating to temperatures in excess of 450 °C leads to a decrease in the intensity of all the adsorbate vibrational bands, and by 600 °C the decomposition of Me 3 Al is essentially complete.…”

Section: Adsorbate Characterization and Thermal Decompositionmentioning

confidence: 99%

See 1 more Smart Citation

Resonant and Nonresonant Vibrational and Electronic Excitations in Trimethylaluminum Adsorbed on GaAs

Mulcahy¹,

Eggeling²,

Gould³

et al. 1999

J. Phys. Chem. B

View full text Add to dashboard Cite

The vibrational and electronic excitations of trimethyaluminum (Me3Al) adsorbed on GaAs(100) have been studied using high-resolution electron energy loss spectroscopy (HREELS). The C−H vibrational modes of the adsorbed Me groups are excited by a resonance scattering mechanism involving the formation of a temporary negative ion. Strong vibrational mode enhancement occurs at 4, 8, and 14 eV with several overtone and combination bands observed at these energies. Reflectivity measurements of both the clean and adsorbate-covered surface are consistent with resonance scattering at these energies. The molecular orbitals involved in the resonant process are identifed through calculation of electron affinities and charge distributions for the free Me3Al molecule. HREEL spectra recorded at electron beam energies greater than 10 eV reveal new vibrational modes not associated with CH3 groups but characteristic of adsorbed CH2, a species also formed after annealing the Me3Al exposed surface to temperatures greater than 350 °C. Electron beam induced dissociation of the Me groups occurs with a threshold energy of 10 eV, and the dissociation cross section for CH2 production is very large, varying from 0.7 × 10-16 cm2 at 20 eV to 2.0 × 10-16 cm2 at 30 eV. The results are consistent with a nonresonant dissociation mechanism, and an electron impact ionization mechanism is proposed. The high cross sections reflect the relatively long lifetime of the dissociative excited states, which are not quenched efficiently for adsorption on semiconductor surfaces.

show abstract

References

2018

Vibrational Spectra of Organometallics

View full text Add to dashboard Cite

Vibrational spectra and structure of (SiH3)2CH2 and (SiD3)2CH2

Cited by 25 publications

References 11 publications

Structure, Vibrational Spectra, and DFT and ab Initio Calculations of Silacyclobutanes

Structure, Vibrational Spectra, and DFT and ab Initio Calculations of Silacyclobutanes

Resonant and Nonresonant Vibrational and Electronic Excitations in Trimethylaluminum Adsorbed on GaAs

References

Contact Info

Product

Resources

About