Halogenated silanes, radicals, and cations: Theoretical predictions on ionization energies, structures and potential energy surfaces of cations, proton affinities, and enthalpies of formation

Wang, Lingyu; He, Yi-Liang

doi:10.1016/j.ijms.2008.07.004

Cited by 21 publications

(24 citation statements)

References 105 publications

(387 reference statements)

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“…, and [CX-YH] ? (X/Y = F, Cl, Br) are also located here, being similar to the Si and Ge systems [77,84]. Bond strengths and the charge transfer to HX moieties (NBO) for these ion complexes are listed in Table 2.…”

Section: Resultsmentioning

confidence: 63%

“…11.07 ± 0.03/PI [20] EVA NIST evaluation (http://webbook.nist.gov/chemistry), G2/3 Gaussian-2/3 calculation, PE photoelectron spectroscopy, PI photoionization mass spectroscopy, PEPI (T)PEPICO (threshold photoelectron-photoion coincidence) 11.64 ± 0.04/PI [33] 11.71/PI [18] 11.92 ± 0.02/PEPI [55] 12.07 ± 0.02/PI [64] 12.095 ± 0.005/PI [ 11.496 ± 0.010/PEPI [59] 12.80 ± 0.03/PEPI [54] 11.509 ± 0.002/PEPI [63] 12.74 ± 0.02/PEPI [60] CClBr [77,84].…”

Section: Resultsmentioning

confidence: 99%

“…H. This means that one should use caution in deriving the relative energetics of cation fragments directly from the measured AEs. Our recent study on halosilane cations has also found that several transition states were higher in energy than the fragment limits [77]. Here, we present a systematic theoretical study on the structures, transition states, and energetics of cations of F-, Cl-, and/or Br-substituted methanes and radicals.…”

Section: Introductionmentioning

confidence: 85%

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Cations of halogenated methanes: adiabatic ionization energies, potential energy surfaces, and ion fragment appearance energies

Wang

2009

Struct Chem

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The DFT-B3LYP and G3X model chemistry were used to predict the cation structures and energetics of fluorinated, chlorinated, and brominated methanes. Ion-complex structures between methylene cations and HX (X = F, Cl, Br) were found for all H-containing cations, and [CHF-FH] ? , [CF 2 -FH] ? , [CCl 2 -ClH] ? , and [CCl 2 -FH] ? structures are more stable than their normal tetravalent structures. Several cations should also be better described as ion-complex structures between methyl cations and halogen atoms, e.g., [CF 3 -Br] ? . Transition states connecting normal and ion-complex structures were also located, and potential energy diagrams were constructed for decomposition of methane cations and to predict the fragmentation pathways. The G3X energies were used to predict the adiabatic ionization energies (IE a s) and ion fragment appearance energies (AEs) from methanes. Many of the experimental AEs correspond to the energies of transition states instead of the thermodynamic dissociation limits.

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Section: Resultsmentioning

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 85%

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Cations of halogenated methanes: adiabatic ionization energies, potential energy surfaces, and ion fragment appearance energies

Wang

2009

Struct Chem

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“…Experimental PA of 1,4-benzoquinone was 191.4 kcal·mol −1 [ 60 ]. In our case, we calculated thermodynamic parameters such as proton affinity (PA) and gas-phase basicity (GB) [ 60 , 61 , 62 ], for the protonation of all oxygen and nitrogen atoms in the molecules. The results for all protonation sites are included in the supplementary materials (Tables S83–S88) .…”

Section: Resultsmentioning

confidence: 99%

Protonation Sites, Tandem Mass Spectrometry and Computational Calculations of o-Carbonyl Carbazolequinone Derivatives

Martínez-Cifuentes

Clavijo-Allancan

Zuñiga-Hormazabal

et al. 2016

IJMS

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A series of a new type of tetracyclic carbazolequinones incorporating a carbonyl group at the ortho position relative to the quinone moiety was synthesized and analyzed by tandem electrospray ionization mass spectrometry (ESI/MS-MS), using Collision-Induced Dissociation (CID) to dissociate the protonated species. Theoretical parameters such as molecular electrostatic potential (MEP), local Fukui functions and local Parr function for electrophilic attack as well as proton affinity (PA) and gas phase basicity (GB), were used to explain the preferred protonation sites. Transition states of some main fragmentation routes were obtained and the energies calculated at density functional theory (DFT) B3LYP level were compared with the obtained by ab initio quadratic configuration interaction with single and double excitation (QCISD). The results are in accordance with the observed distribution of ions. The nature of the substituents in the aromatic ring has a notable impact on the fragmentation routes of the molecules.

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“…24 At 1280 K, m/z 15 grows, and peaks emerge at m/z 98 and m/z 100 with the 3 : 2 ratio characteristic of SiCl 2 (with an IE of 9.6 eV). 25 The SiCl 2 product could be formed via reaction (R5), while the CH 3 Cl co-product could not be detected because of its high IE of 11.22 eV. 24,26 However, reaction (R5) is unlikely because of its high reaction barrier of 456 kJ mol -1 .…”

Section: •+mentioning

confidence: 99%

Letter: Thermal Decomposition of Methyltrichlorosilane, Dimethyldichlorosilane and Methyldichlorosilane by Flash Pyrolysis Vacuum Ultraviolet Photoionization Time-of-Flight Mass Spectrometry

Lemieux

Zhang

2014

Eur J Mass Spectrom (Chichester)

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The thermal decompositions of methyltrichlorosilane (MTS) (CH3SiCl3), dimethyldichlorosilane (Si(CH3)2Cl2), and methyldichlorosilane (SiHCH3Cl2) were studied at temperatures from -1000 K to 1500 K on a short timescale of 20 μs to 100 μs using flash pyrolysis vacuum ultraviolet single-photon ionization time-of-flight mass spectrometry. The pyrolysis of MTS proceeds primarily via Si-C bond homolysis to form the SiCl3 and methyl radicals. At elevated temperatures, SiCl2 production from secondary decomposition of SiCl3 becomes more important, and other pyrolysis pathways of MTS, including C-H bond fission and HCl elimination make minor contributions. The pyrolysis of Si(CH3)2Cl2 occurs mainly by the sequential loss of methyl radicals, ultimately forming a significant amount of SiCl2. Si(CH3)2Cl2 also has two minor decomposition channels at higher temperatures, molecular elimination of CH4 to form SiCH2Cl2 and of CH3Cl to form SiCH3Cl. The pyrolysis of SiHCH3Cl2 mainly undergoes sequential CH3 and H loss and/or molecular elimination of CH4 to form SiCl2, while molecular elimination of HCl to form SiCH3Cl also contributes. SiCl2 is produced in significant concentrations in the pyrolysis of all three molecules, suggesting that it is an important intermediate in SiC chemical vapor deposition from chloroorganosilanes.

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Halogenated silanes, radicals, and cations: Theoretical predictions on ionization energies, structures and potential energy surfaces of cations, proton affinities, and enthalpies of formation

Cited by 21 publications

References 105 publications

Cations of halogenated methanes: adiabatic ionization energies, potential energy surfaces, and ion fragment appearance energies

Cations of halogenated methanes: adiabatic ionization energies, potential energy surfaces, and ion fragment appearance energies

Protonation Sites, Tandem Mass Spectrometry and Computational Calculations of o-Carbonyl Carbazolequinone Derivatives

Letter: Thermal Decomposition of Methyltrichlorosilane, Dimethyldichlorosilane and Methyldichlorosilane by Flash Pyrolysis Vacuum Ultraviolet Photoionization Time-of-Flight Mass Spectrometry

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