Microwave, infrared and Raman spectra, adjusted r0 structural parameters, conformational stability, and vibrational assignment of cyclopropylfluorosilane

Panikar, Savitha S.; Guirgis, Gamil A.; Eddens, Matthew T.; Dukes, Horace W.; Conrad, Andrew R.; Tubergen, Michael J.; Gounev, Todor K.; Durig, J. R.

doi:10.1016/j.chemphys.2012.12.036

Cited by 4 publications

(9 citation statements)

References 30 publications

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“…These predicted values are expected to be reasonably near the unknown experimental ones that would be obtained from the frequencies of the asymmetric torsional modes from the two conformers. Potential function results obtained for cyclopropylcyanosilane molecules are consistent with previously reported potential function values for cyclopropyl fluoro, chloro, bromo and methyl silane [4][5][6][7].…”

Section: Discussionsupporting

confidence: 92%

“…However, B3LYP calculations from all the basis sets utilized predicted the gauche conformer as most stable form by an average value of 15 cm À1 (0.18 kJ mol À1 ). For cyclopropyl fluoro, chloro and bromo silanes (c-C3H5SiH2-X; X = F, Cl, Br) the enthalpy difference between the two conformers were determined to be 109 ± 19 cm À1 , 98 ± 13 cm À1 and 126 ± 15 cm À1 with gauche conformer the most stable form for cyclopropylfluorosilane whereas for both cyclopropylchlorosilane and cyclopropylbromosilane cis conformer was observed to be most stable conformer [4][5][6]. For cyanomethylcyclopropane, the enthalpy difference between the cis and the gauche conformer was determined to be 54 ± 4 cm À1 with gauche conformer being the more stable form [39].…”

Section: Discussionmentioning

confidence: 99%

“…It is interesting to note that in cyclopropylchlorosilane and cyclopropylbromosilane both the gauche and cis conformers were present in the liquid phase and only the gauche conformer was present in the solid phase [5,6]. At ambient temperature, 23 ± 2% of cyclopropylfluorosilane was in the cis form, whereas for the cyclopropylbromosilane, the ratio of gauche to cis conformers was almost equal [4,5]. For cyclopropylsilane derivatives, conformational stability changes with respect to substitution of halogen in the silane moiety.…”

Section: Introductionmentioning

confidence: 96%

“…The enthalpy difference was determined to be 109 ± 9 cm À1 (1.30 ± 0.1 kJ/mol) for cyclopropylfluorosilane with the gauche form the most stable conformer, whereas for cyclopropylchlorosilane and cyclopropylbromosilane, the cis conformer was the more stable form with the enthalpy difference of 98 ± 10 cm À1 (1.2 ± 0.12 kJ/mol) and 126 ± 25 cm À1 (1.51 ± 0.30 kJ/mol), respectively, [4][5][6]. It is interesting to note that in cyclopropylchlorosilane and cyclopropylbromosilane both the gauche and cis conformers were present in the liquid phase and only the gauche conformer was present in the solid phase [5,6].…”

Section: Introductionmentioning

confidence: 97%

“…We further investigated cyclopropylfluorosilane [4], cyclopropylchlorosilane [5] and cyclopropylbromosilane [6]. The enthalpy difference was determined to be 109 ± 9 cm À1 (1.30 ± 0.1 kJ/mol) for cyclopropylfluorosilane with the gauche form the most stable conformer, whereas for cyclopropylchlorosilane and cyclopropylbromosilane, the cis conformer was the more stable form with the enthalpy difference of 98 ± 10 cm À1 (1.2 ± 0.12 kJ/mol) and 126 ± 25 cm À1 (1.51 ± 0.30 kJ/mol), respectively, [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

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Microwave, r0 structural parameters, conformational stability and vibrational assignment of cyclopropylcyanosilane

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Microwave, r0 structural parameters, conformational stability and vibrational assignment of cyclopropylcyanosilane

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Molecular Structure of Cyclopropyl (Isocyanato) Silane: A Combined Microwave Spectral and Theoretical Study

et al. 2015

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The molecular equilibrium structures of two conformers (cis and gauche) of C3H5-SiH2-NCO have been deduced by a combination of microwave (MW) spectra at natural abundance including data from (13)C and (29,30)Si isotopomers and ab initio calculations. The MW rotational constants (RCs) for the most abundant isotopes are cis: A = 4216.3617(64), B = 1225.76654(91), and C = 1037.31468(77) MHz and gauche: A = 4955.55(79), B = 1094.9276(81), and C = 942.7031(80) MHz. The symmetric quartic centrifugal distortion constants have been evaluated for the cis conformer, using the I(r) representation for CS symmetry. Only partial substitution structures (PSSs) could be derived from the spectra after inclusion of the above isotopic combinations at each center. Using the PSSs, the full structures were determined by ab initio calculation of the equilibrium structures using coupled-cluster singles and doubles with selected triples configuration calculations (CCSD(T)); the two conformers have an energy difference of 228 cm(-1) (cis lower than gauche). The similarity of the calculated and MW RC results confirms the identities of the two compounds. The more interesting cis conformer has bond lengths C2-Si3, 1.9072(73), C2-C9 1.464(22), and C9-C10 1.4944(33) Å and angles Si3-C2-C10 119.4(12)° and C9-C2-C10 57.1(12)°, with similar results for the gauche conformer. The Si3N4C5 angle is wide in the cis conformer (145°) and nearly linear in the gauche conformer (179°). New physical insights into the bonding of cis conformers of this type have led the identification of an attractive force between the relatively crowded cyclopropyl and isocyanato groups in the cis conformation. This is demonstrated by three methods: Comparing electronic charges (both AIMALL and Mulliken analyses) in the pair of conformers shows a relative shift of density between these groups in the cis compound. Comparison of the highest occupied molecular orbitals (HOMOs) shows major mixing of density, exemplified by HOMO-1 in these structural units for the cis conformer but which is absent for the gauche conformer. Finally, the nearly linear isocyanate moiety (and the molecular dipole moment) of the cis conformer points closely toward the connected C atom of the cyclopropyl ring, while the gauche conformer dipole moment is significantly different in direction and points toward the midpoint of the C2Si3 bond. Both the HCSiN torsional and Si-N═C bending surfaces connecting these conformers were explored at the Møller-Plesset second-order perturbation theory level (MP2), which led to the exclusion of other conformers. The bending surface shows a very high amount of quartic potential function.

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Microwave, infrared and Raman spectra, adjusted r0 structural parameters, conformational stability, and vibrational assignment of cyclopropylfluorosilane

Cited by 4 publications

References 30 publications

Microwave, r0 structural parameters, conformational stability and vibrational assignment of cyclopropylcyanosilane

Microwave, r0 structural parameters, conformational stability and vibrational assignment of cyclopropylcyanosilane

Molecules with Three Carbon Atoms

Molecular Structure of Cyclopropyl (Isocyanato) Silane: A Combined Microwave Spectral and Theoretical Study

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