Kinetics and mechanism of pyrolysis of hydridosilacyclobutanes

Davidson, Iain; Fenton, Andrew.; Ijadi-Maghsoodi, S.; Scampton, R. J.; Auner, Norbert; Grobe, J.; Tillman, Nolan; Barton, Thomas J.

doi:10.1021/om00088a026

Cited by 32 publications

(28 citation statements)

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“…The thermal decomposition of silacyclobutane (1), 1-methylsilacyclobutane (2), and 1,1-dimethylsilacyclobutane (3) has been studied at various DFT levels of theory. The B3LYP/6-311G * * level of theory gives activation energies very close to the experimental values and the decomposition barrier heights decrease from compounds 1 to 3.…”

Section: Discussionmentioning

confidence: 99%

“…The energies of IRC calculations are given in Table 4. IRC calculations demonstrated that the transition state connects the reactant and corresponding products in the reaction path (see Figures 2,3,4). Calculations showed that the reaction path through a four-membered ring is unique to the formation of ethylene and corresponding silene.…”

Section: Kinetic and Thermodynamic Parametersmentioning

confidence: 96%

“…A second important difference between cyclobutane and silacyclobutane is that in the latter compound there are two possible initiating diradical processes. [3][4][5][6][7] A recent ab initio study had suggested that the most likely route of the [2 + 2]cycloreversion of silacyclobutane to ethylene and silene is the initial cleavage of a ring C C bond to form a trans-diradical, followed by the rupture of the central Si C bond. Production of propylsilylene should be both thermodynamically and kinetically competitive with the [2 + 2]cycloreversion.…”

Section: Introductionmentioning

confidence: 99%

“…The results are given in Table 1. 2,3 The simplest explanation is that the primary process forming ethene in each case is the same but that there may be secondary reactions of low activation energies forming more ethene from compounds 1 and 2. 3 We have calculated the rate coefficient and the thermodynamic parameters shown in Table 1, but the main goal of this work is to understand the influence of the effective factors on the transition state structures of the decomposition kinetics of compounds 1-3, involving the formation of ethene and the corresponding silene by using density functional theory (DFT)-based methods (B3LYP, B3PW91, and MPW1PW91), and to compare them with experimental values.…”

Section: Introductionmentioning

confidence: 99%

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DFT Calculations of the Elimination Kinetics of Silacyclobutanes and its Methyl Derivatives in the Gas-Phase

Shiroudi¹,

Zahedi²

2012

Phosphorus, Sulfur, and Silicon and the Related Elements

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The gas-phase thermal decomposition kinetics of silacyclobutane (1), 1-methylsilacyclobutane (2), and 1,1-dimethyl-1-silacyclobutane (3) has been theoretically studied at the B3LYP/6-311G * * , B3PW91/6-311G * * , and MPW1PW91/6-311G * * levels. The B3LYP/6-311G * * method was found to give a reasonable good agreement with the experimental kinetics and thermodynamic parameters. The decomposition reaction of compounds 1-3 yields ethylene and the corresponding silene. Based on the optimized ground state geometries using B3LYP/6-311G * * method, the natural bond orbital (NBO) analysis of donor-acceptor (bonding-antibonding) interactions revealed that the perturbation energies (E 2 ) associated with the electronic delocalization from σ Si1-C2 to σ * C4-Si1 orbitals increase from compounds 1 to 3. The σ Si1-C2 →σ * C4-Si1 resonance energies for compounds 1-3 are 1.17, 1.26, and 1.43 kcal/mol, respectively. Also, the decomposition process in these compounds is controlled by σ →σ * resonance energies. Moreover, the obtained order of energy barriers could be explained by the number of electron-releasing methyl groups substituted to the Si sp2 atom. NBO analysis shows that the occupancies of σ Si1-C2 bonds decrease for compounds 1-3 as 3 < 2 < 1, and the occupancies of σ * Si1-C2 bonds increase in the opposite order (3 > 2 > 1). Moreover, these results can fairly explain the decrease of the energy barriers ( E o ) of the decomposition reaction of compounds 1 to 3. The calculated data demonstrate that in the decomposition process 619 Downloaded by [McMaster University] at 07:15 17 March 2015 620 A. SHIROUDI AND E. ZAHEDI of the studied compounds, the polarization of the C 3 -C 4 bond is the rate determining factor. Analysis of bond orders, NBO charges, bond indexes, synchronicity parameters, and IRC calculations indicate that these reactions are occurring through a concerted and asynchronous four-membered cyclic transition state type of mechanism.

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Section: Discussionmentioning

confidence: 99%

Section: Kinetic and Thermodynamic Parametersmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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DFT Calculations of the Elimination Kinetics of Silacyclobutanes and its Methyl Derivatives in the Gas-Phase

Shiroudi¹,

Zahedi²

2012

Phosphorus, Sulfur, and Silicon and the Related Elements

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“…In numerous papers it has been shown that the thermolysis or flash photolosis of silacyclobutanes leads to either intermediate or stable divalent silicon compounds like silenes R 2 Si@C and silylenes R 2 Si: [8][9][10][11][12][13][14][15]. Silacyclobutanes have been recently utilized as carbanion pump in anionic living polymerization for the synthesis of block copolymers [16,17].…”

Section: Introductionmentioning

confidence: 99%

A gas-phase electron diffraction and quantum chemical investigation of the molecular structure of 1-bromosilacyclobutane

Dakkouri

Novikov

Vilkov

2010

Journal of Molecular Structure

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Si/C Phases from the IR Laser-induced Decomposition of Silacyclobutane and 1,3-Disilacyclobutane

Bastl¹,

Bürger²,

Fajgаr³

et al. 1996

Appl. Organometal. Chem.

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CO2 laser‐induced infrared multiphoton decomposition (IRMPD) and SF6 photosensitized decomposition (LPD) of silacyclobutane (SCB) and 1,3‐disilacyclobutane (DSCB) in the gas phase results in the very efficient deposition of Si/C/H and SiC materials, and it is inferred that the process is dominated by formation of transient silene; silene rearrangement to methylsilylene; silene and methylsilylene dehydrogenation; and polymerization of SiCHn (n < 4) species. The deposits are sensitive to oxygen. Decomposition and SiC formation are favoured with IRMPD experiments conducted with high‐energy fluxes. The laser technique is promising for low‐temperature chemical vapour deposition of amorphous SiC.

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Kinetics and mechanism of pyrolysis of hydridosilacyclobutanes

Cited by 32 publications

References 0 publications

DFT Calculations of the Elimination Kinetics of Silacyclobutanes and its Methyl Derivatives in the Gas-Phase

DFT Calculations of the Elimination Kinetics of Silacyclobutanes and its Methyl Derivatives in the Gas-Phase

A gas-phase electron diffraction and quantum chemical investigation of the molecular structure of 1-bromosilacyclobutane

Si/C Phases from the IR Laser-induced Decomposition of Silacyclobutane and 1,3-Disilacyclobutane

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