The conformations of bromomethyl dimethyl silane and bromomethyl dimethyl silane-d1 as studied by vibrational spectroscopy and by ab initio calculations

Aleksa, Valdemaras; Klæboe, P.; Nielsen, Claus J.; Tanevska, Vinka; Guirgis, Gamil A.

doi:10.1016/s0924-2031(98)00019-8

Cited by 16 publications

(4 citation statements)

References 23 publications

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“…Moreover, we wanted to compare the SiH 3 and SiD 3 group wavenumbers in TFPS and TFPSD with those in n-propylsilane 7 and 2-chloroethylsilane, 8 and take into account the older vibrational studies of a number of alkylsilanes. 9,10 In addition to the ethane-like silanes, various molecules containing a central C-Si bond have been investigated, most recently chloromethyl methyldichlorosilane, 11 dichloromethyl methyl dichlorosilane 12 and chloromethylmethyl dichlorosilane. 13 A number of disilanes 14 -16 with Si-Si and trisilanes 17,18 and with Si-Si-Si linkages have been synthesized by Hassler and coworkers and their vibrational spectra reported.…”

Section: Introductionmentioning

confidence: 99%

Vibrational spectroscopic studies, conformations and quantum chemical calculations of 3,3,3‐trifluoropropyl‐ silane and 3,3,3‐trifluoropropylsilane‐d₃

Klæboe

Guirgis

Witkowski

et al. 2006

J Raman Spectroscopy

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were obtained in the vapour, liquid, and crystalline solid phases in the range 4000-50 cm −1 . Additional spectra in argon matrices at 5 K were recorded before and after annealing to temperatures 20-34 K. Raman spectra of the compounds as liquids were recorded at various temperatures between 296 and 183 K and spectra of the amorphous and crystalline solids were obtained.The spectra revealed the existence of two conformers (anti and gauche) in the fluid phases and in the matrices. When the two vapours were shock-frozen on a cold finger at 78 K, they turned partly crystalline immediately. After subsequent annealing to 140-150 K, ca 7-9 Raman bands of both molecules present in the liquids vanished in the crystal. Similar variations in intensity were observed in the corresponding infrared spectra before and after annealing. The spectra revealed the existence of one conformer (anti) in the crystal.From Raman intensity variations of three independent pairs of anti and gauche bands between 298 and 173 K for the parent compound, and 298 and 183 K for the deuterated analogue, the values 1 conf H o .gauche−anti/ = 4.1 ± 0.3 kJ mol −1 for the parent compound and the same value for the deuterated species were obtained in the liquid state. Annealing experiments in the matrices show that the gauche bands vanish after annealing, demonstrating that the anti conformer also has the lower energy here and that the barrier to gauche → anti inter-conversion is around 5-6 kJ mol −1 . The spectra of both conformers have been interpreted in detail.Ab initio and DFT calculations at the HF/6-311G**, B3LYP/6-311 G** and MP2/6-311 G** levels gave optimized geometries, infrared and Raman intensities and vibrational wavenumbers for the anti and gauche conformers. The conformational enthalpy difference derived from the calculations was between 6.0 and 4.1 kJ mol −1 with anti being the low energy conformer.

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Section: Introductionmentioning

confidence: 99%

Vibrational spectroscopic studies, conformations and quantum chemical calculations of 3,3,3‐trifluoropropyl‐ silane and 3,3,3‐trifluoropropylsilane‐d₃

Klæboe

Guirgis

Witkowski

et al. 2006

J Raman Spectroscopy

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“…26 Frequently, these crystals are stable and metastable, meaning that when a stable crystal is formed it cannot be transformed into a metastable crystal. 20 In CMDFS and dichloromethylmethyldifluorosilane 1 two crystals with different conformers were observed for both molecules, a metastable crystal I and a stable crystal II, containing the gauche and anti conformers, respectively. In cyclohexylallene 29 the two dominant conformers had the allene group in the equatorial (e) position and a gauche conformer of the allene was found in the metastable and an anti conformer in the stable crystal.…”

Section: Phase Transitionsmentioning

confidence: 99%

The conformers of chloromethylmethyldifluorosilane studied by vibrational spectroscopy andab initio methods

Aleksa

Klæboe

Nielsen

et al. 2000

J. Raman Spectrosc.

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“…In three halogenated silanes dichloromethyldifluoromethylsilane, 24 bromomethyldimethylsilane and the Si deuterated analogue 25 and chloromethylmethyldifluorosilane 26 two different crystals were found. They were obtained by selective annealing of an amorphous solid, formed by depositing the vapour on a cold window (or cold finger) at 80 K. In all three compounds one of the two crystals appeared to be stable whereas the other was metastable, but each crystal contained a different conformer.…”

Section: Phase Transitionsmentioning

confidence: 99%

Conformational equilibria, Raman and infrared spectra and ab initio calculations of dichloromethylmethyldichlorosilane

Aleksa

Gruodis

Powell

et al. 2001

J Raman Spectroscopy

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The infrared spectra of dichloromethylmethyldichlorosilane (Cl 2 CHCH 3 SiCl 2 ) were recorded in the vapour, amorphous and partly crystalline phases and when isolated in argon, nitrogen and krypton matrices at 5 K. Raman spectra of the liquid were recorded at various temperatures between 295 and 147 K. Spectra of the amorphous and annealed crystal deposited on a copper finger at 80 K were obtained. The spectra showed the existence of two conformers, anti and gauche, in the vapour and in the liquid. Approximately 12 infrared bands were reduced in intensity, and six of the same bands present in the fluid phases in the Raman spectra vanished upon crystallization. From the intensity variations of two band pairs with temperature, a 1H • value of 0.4 ± 0.3 kJ mol −1 between the conformers was obtained in the liquid, anti being the low-energy conformer. Small increases and decreases in the IR band intensities were observed in the matrix spectra after annealing to 32 K (nitrogen), 36 K (argon) and 50 K (krypton). The enthalpy difference between the conformers is low in the matrices, but the anti conformer had lower energy than the gauche conformer. Ab initio calculations were performed at the HF/6-311G * level and gave optimized geometries, vibrational wavenumbers and infrared and Raman intensities for the anti and gauche conformers. The conformational energy derived was 4.4 kJ mol −1 with anti being the low-energy conformer. The dipole moments were calculated to be 1.2 and 3.1 D for the anti and gauche conformers, respectively. Correlation between the observed and calculated wavenumbers of both conformers revealed that anti was present in the crystal, and complete assignments of the spectra were carried out.

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The conformations of bromomethyl dimethyl silane and bromomethyl dimethyl silane-d1 as studied by vibrational spectroscopy and by ab initio calculations

Cited by 16 publications

References 23 publications

Vibrational spectroscopic studies, conformations and quantum chemical calculations of 3,3,3‐trifluoropropyl‐ silane and 3,3,3‐trifluoropropylsilane‐d₃

Vibrational spectroscopic studies, conformations and quantum chemical calculations of 3,3,3‐trifluoropropyl‐ silane and 3,3,3‐trifluoropropylsilane‐d₃

The conformers of chloromethylmethyldifluorosilane studied by vibrational spectroscopy andab initio methods

Conformational equilibria, Raman and infrared spectra and ab initio calculations of dichloromethylmethyldichlorosilane

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The conformations of bromomethyl dimethyl silane and bromomethyl dimethyl silane-d1 as studied by vibrational spectroscopy and by ab initio calculations

Cited by 16 publications

References 23 publications

Vibrational spectroscopic studies, conformations and quantum chemical calculations of 3,3,3‐trifluoropropyl‐ silane and 3,3,3‐trifluoropropylsilane‐d3

Vibrational spectroscopic studies, conformations and quantum chemical calculations of 3,3,3‐trifluoropropyl‐ silane and 3,3,3‐trifluoropropylsilane‐d3

The conformers of chloromethylmethyldifluorosilane studied by vibrational spectroscopy andab initio methods

Conformational equilibria, Raman and infrared spectra and ab initio calculations of dichloromethylmethyldichlorosilane

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Vibrational spectroscopic studies, conformations and quantum chemical calculations of 3,3,3‐trifluoropropyl‐ silane and 3,3,3‐trifluoropropylsilane‐d₃

Vibrational spectroscopic studies, conformations and quantum chemical calculations of 3,3,3‐trifluoropropyl‐ silane and 3,3,3‐trifluoropropylsilane‐d₃