Theoretical study of methyl- and chloro-substituted disilenes, silylsilylenes, and related molecules

Bell, T. N.; Kieran, Arielle; Perkins, Kathryn A.; Perkins, P. G.

doi:10.1021/j150651a020

Cited by 6 publications

(3 citation statements)

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“…Our value of -94.3 kcal/mol is in good agreement with this. The semiempirical (MOBI) calculations of Bell et al 11 gave heats of formation that were 15-35 kcal/ mol lower than those we present here. This poor agreement is not surprising, since the MOBI method has been shown to be unreliable for silicon compounds.…”

Section: Resultscontrasting

confidence: 73%

“…Allendorf and Melius 10 have calculated heats of formation of Cl 3 SiSiCl and Cl 2 SiSiCl 2 using the BAC-MP4 methodology. Bell et al 11 calculated energies for all of the chlorinated silylsilylenes and disilenes using the semiempirical MOBI method. To our knowledge the isomerizations between the chlorinated silylsilylenes and disilenes have not previously been studied theoretically or experimentally.…”

Section: Introductionmentioning

confidence: 99%

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Ab Initio Molecular Orbital Study of the Thermochemistry and Reactions of the Chlorinated Disilenes and Their Isomers (Si₂H_nCl_4-n)

Swihart

Carr

1998

J. Phys. Chem. A

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Structures, vibrational frequencies, and energies for the chlorinated disilenes, their dibridged isomers, and the transition states connecting the chlorinated disilenes to the corresponding silylsilylenes are presented. Geometries and frequencies were obtained at the MP2/6-31G(d,p) level, and energetics were calculated at the G2, G2(MP2), MP4/6-31+G(2df,p), and/or MP2/6-31+G(2df,p) levels of theory, depending on the number of chlorine atoms in the molecule. The silylsilylene isomer with the structure H n Cl 3-n SiSiCl was found to be lowest in energy for all of the chlorinated compounds. The dibridged structures are all significantly higher in energy than the silylsilylene and disilene structures. Barriers for isomerization by H transfer and Cl transfer ranged from 5 to 18 kcal/mol and 9 to 23 kcal/mol above the disilene, respectively. Energies along paths for decomposition of the chlorinated disilenes to pairs of silylenes are presented, confirming that the reverse reactions are barrierless. Finally, energetics of various decomposition products of the Si 2 H n Cl 4-n compounds are considered. It is shown that for the species with two or more chlorines, decomposition to a pair of silylenes should be the dominant reaction path based on the energetics of competing paths. The isomerization barriers are much smaller than decomposition barriers, so the isomerization reactions will be fast compared to decomposition.

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Section: Resultscontrasting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Ab Initio Molecular Orbital Study of the Thermochemistry and Reactions of the Chlorinated Disilenes and Their Isomers (Si₂H_nCl_4-n)

Swihart

Carr

1998

J. Phys. Chem. A

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“…Methods, results and discussion The molecular orbital -bond index method (MOBI) has been formulated and extensively used in studies of the reactions of hydrocarbons and of the thermodynamics of silane derivatives (3)(4)(5)(6)(7). The technique starts from a rotationally invariant quantity, the bond index.…”

Section: Introductionmentioning

confidence: 99%

Calculations on the relative energies of complexes of silanes with ²π and ⁴πNO

Bell¹,

Perkins²,

Perkins³

1987

Can. J. Chem.

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A theoretical study is presented of the relative enthalpies (calculated through heats of atomisation) of complexes of the silanes SiF4, SiF3Me, and SiF2Me2, with ground state %NO, and exciplexes with excited state 4~N 0 .The calculations favour an increasing relative stability of the complexes and exciplexes with silanes in the order SiF4 < F3SiMe < F2SiMez with, in 4 . each particular case, a geometry favouring the -SiON over the IntroductionBond indices for simple molecules such as hydrocarbons Sensitisation of NO by ~~( 6 3~~) atoms leads to 4 . r r N~ follow a pattern which correlates with the chemist's concept of which provides a route to decomposition into the observed (1) multiplicity of bonds; thus, for ethane, ethylene, and acetylene products NZ, 0 2 , and N20. The decomposition quantum yields the C-C bond indices are, respectively, 1.023, 2.032, and are markedly enhanced (2) by the methylfluorosilanes with the 2.998. Following this trend we have suggested that such bond

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A theoretical study of adsorption equilibria in silicon CVD

Gardeniers

Giling

Jong

et al. 1990

Journal of Crystal Growth

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As part of a theoretical study of adsorption processes in the chemical vapour deposition of silicon, thermochemical data are derived for the adsorption of Si-H species on the Si(111) and the dimer-reconstructed Si(001)-(2 xl) surfaces. Essential contributions to the heats of adsorption appear to be electron pairing and two-and three-body interactions. It is shown that when the bond energies are defined in this way, also a consistent description of the bonds in silicon hydrides is provided. This demonstrates that with reasonable confidence the method can be applied to the adsorption process itself. Data are derived for species which may form one, two or even four bonds with the surface. It is assumed that on the (111) surface adsorbates bind on the "dangling bonds" which are present on this surface in a broken bond model. It is demonstrated that on the dimer reconstructed Si(001)-(2 xl) surface, adsorbates will either bind on the surface atoms with one or two bonds, without the breaking of the dimer bonds, or, if the species have the possibility to form two or four bonds with the surface atoms, may become inserted into the dimer bonds. With the aid of the derived thermochemical data for adsorption and the Langmuir isotherm or modifications thereof, the coverage of the Si(111) and the dimer reconstructed Si(001)-(2X1) surfaces with species from the Si-H system is calculated. It is found that the equilibrium surface coverages of the Si(111) and the Si(001)-(2 xl) surfaces are very similar: the hydrogen coverage is high at all temperatures, while at low supersaturation the coverage with growth species is very low on both surfaces.

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Theoretical study of methyl- and chloro-substituted disilenes, silylsilylenes, and related molecules

Cited by 6 publications

References 0 publications

Ab Initio Molecular Orbital Study of the Thermochemistry and Reactions of the Chlorinated Disilenes and Their Isomers (Si₂H_nCl_4-n)

Ab Initio Molecular Orbital Study of the Thermochemistry and Reactions of the Chlorinated Disilenes and Their Isomers (Si₂H_nCl_4-n)

Calculations on the relative energies of complexes of silanes with ²π and ⁴πNO

A theoretical study of adsorption equilibria in silicon CVD

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Theoretical study of methyl- and chloro-substituted disilenes, silylsilylenes, and related molecules

Cited by 6 publications

References 0 publications

Ab Initio Molecular Orbital Study of the Thermochemistry and Reactions of the Chlorinated Disilenes and Their Isomers (Si2HnCl4-n)

Ab Initio Molecular Orbital Study of the Thermochemistry and Reactions of the Chlorinated Disilenes and Their Isomers (Si2HnCl4-n)

Calculations on the relative energies of complexes of silanes with 2π and 4πNO

A theoretical study of adsorption equilibria in silicon CVD

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Ab Initio Molecular Orbital Study of the Thermochemistry and Reactions of the Chlorinated Disilenes and Their Isomers (Si₂H_nCl_4-n)

Ab Initio Molecular Orbital Study of the Thermochemistry and Reactions of the Chlorinated Disilenes and Their Isomers (Si₂H_nCl_4-n)

Calculations on the relative energies of complexes of silanes with ²π and ⁴πNO