Theoretical, ab initio and DFT, study of the structure and vibrational analysis of Raman, IR and INS spectra of (CH3)3SiNCO

Fernández‐Liencres, M. Paz; Navarro, Amparo; Altabef, A. Ben; González, Juan Jesús López; Fernández-Gómez, Manuel; Kearley, Gordon J.

doi:10.1016/j.chemphys.2006.07.033

Cited by 5 publications

(3 citation statements)

References 53 publications

(97 reference statements)

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“…corresponds to the measured vibrational band of around 626 cm À1 , Fig.S3. † Scaling with several scale factors is not unusual for computed data [18][19][20][21]. The CH x and CO vibrations have scaling factors of around 0.93-0.96, Fig.S2, † whereas the silane vibration has to be scaled by a factor larger, of around 1.19.…”

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confidence: 84%

Analysis of silanes and of siloxanes formation by Raman spectroscopy

Schmitt

2014

RSC Adv.

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The consecutive reactions of acid involved siloxane formation are firstly measured in bulk and analysed by Raman spectroscopy. Influencing factors, which can be identified as the chemical properties of the silanes, the silylium cations, and miscibility are pointed out by using a special technique. The procedure is based on a modified Raman sample cell, which allows a single-phase system with controlled water content to be systematically quantitatively monitored. Additional to the novel opportunity to analyse the acid "catalysed" condensation during the formation of polysiloxanes, this publication contains an alternated theoretical mechanism for sol-gel synthesis considering a restricted water content. A major aspect of this introducing study is a detailed analysis and identification of the relevant Raman vibrational bands and their origin on the hand of ten different organyltrialkoxysilanes (methoxy and ethoxy). The ability to determine the kinetics of the acid catalysed formation is demonstrated on homologous series of alkyltrimethoxysilanes.

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confidence: 84%

Analysis of silanes and of siloxanes formation by Raman spectroscopy

Schmitt

2014

RSC Adv.

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“…TTOD decomposed at fairly low temperature, at 300 1C, and produced trimethylsilylisocyanate and hexamethyldisiloxane according to the gas-phase IR spectrum. (The gasphase IR spectrum of trimethylsilylisocyanate was recently published 26 and that of hexamethyldisiloxane was recorded by us for comparison.) The product ratio was practically un-changed between 300 and 700 1C.…”

Section: Unimolecular Isomerisation and Bond Dissociationmentioning

confidence: 99%

Quantum-chemical study of the structure and stability of pseudohalogens: OCN–NCO and its isomers

Pasinszki

2008

Phys. Chem. Chem. Phys.

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The equilibrium geometries, stability, and isomerisation of pseudohalogen isomers, C(2)N(2)O(2), have been investigated by DFT calculations at the B3LYP level and by ab initio calculations at the CCSD(T) level of theory using the 6-311+G(2d) and cc-pVTZ basis sets, as well as at the CBS-QB3 level. Minimum energy structures and their interconnecting transition states, as well as transition states for bond dissociations have been calculated, and possible isomerisation and decomposition pathways are suggested. Calculations have predicted that four isomers, OCNNCO, ONCCNO, ONCOCN, and ONCNCO are kinetically stable toward unimolecular isomerisation or dissociation at room temperature with the lowest kinetic energy barrier of 209, 232, 159, and 95 kJ mol(-1), respectively (CCSD(T)//B3LYP), and other isomers, like NCONCO, CNONCO, and CNOCNO are unstable. Calculations have also predicted that valence formulations like NCOOCN, CNOOCN, and CNOONC do not represent existing molecules. The gas-phase generation of OCNNCO has been attempted by thermolysing Me(3)SiON(Me(3)SiO)CC(OSiMe(3))NOSiMe(3), synthesised by a novel method from oxalyl chloride and N,O-bis(trimethylsilyl)hydroxylamine; the thermolysis, however, have not produced OCNNCO, but trimethylsilylisocyanate and hexamethyldisiloxane.

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“…[6] A wavenumber of 64 ± 15 cm −1 for the SiNC bend was reported [6] from vibrational satellites of this lowest bending mode, which was later observed [9] in the Raman spectrum of the gas at 37 cm −1 with an overtone at 84 cm −1 . However, from ab initio and DFT calculations, a very low barrier of 4-15 cm −1 has been predicted, [8] which would indicate only one energy level below the barrier. Nevertheless, the observed vibrational spectra could be clearly assigned on the basis of a molecule with C 3V symmetry except for the NCO bend where there are clearly two Raman lines at 612 and 603 cm −1 in the spectrum of the gas.…”

Section: Introductionmentioning

confidence: 99%

Raman and infrared spectra, conformational stability, ab initio calculations and vibrational assignment of dimethylsilylisocyanate

Guirgis

Zhou

Durig

2009

J Raman Spectroscopy

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The Raman (3200-30 cm −1 ) and/or infrared spectra (3500 to 400 cm −1 ) of gaseous, liquid and solid dimethylsilylisocyanate, (CH 3 ) 2 Si(H)NCO, have been recorded. The MP2(full) calculations, employing a variety of basis sets with and without diffusion functions, have been used to predict the structural parameters, conformational stability, vibrational fundamental wavenumbers, Raman activities, depolarization values and infrared intensities to support the vibrational assignment. The low wavenumber Raman spectrum of the gas with a significant number of Q-branches for the SiNC(O) bend is consistent with an essentially linear SiNCO moiety. The ab initio calculations supported this conclusion as all possible orientations of the NCO moiety lead to nearly the same energy. This result is at variance with the conclusion from the electron diffraction study that the heavy atom skeleton was bent with an angle of 152(5) • with one stable cis conformer. It is believed that this reported angle difference from 180 • is due to the shrinkage effect. The SiH distance of 1.486 Å has been obtained from the isolated SiH stretching wavenumber. From the adjustment of the ab initio MP2(full)/6-311+G(d,p) predicted structural parameters, a proposed structure is reported, which is expected to give rotational constants within a few megahertz of the actual ones. These experimental and theoretical results are compared with the corresponding quantities of similar molecules.

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Theoretical, ab initio and DFT, study of the structure and vibrational analysis of Raman, IR and INS spectra of (CH3)3SiNCO

Cited by 5 publications

References 53 publications

Analysis of silanes and of siloxanes formation by Raman spectroscopy

Analysis of silanes and of siloxanes formation by Raman spectroscopy

Quantum-chemical study of the structure and stability of pseudohalogens: OCN–NCO and its isomers

Raman and infrared spectra, conformational stability, ab initio calculations and vibrational assignment of dimethylsilylisocyanate

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