Stepwise bond dissociation energies in sulfur hexafluoride

Kiang, T.; Zare, R. N.

doi:10.1021/ja00532a008

Cited by 102 publications

(69 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Our value confirms the conclusions of Tsang and Herron 29 that the value of the SF 5 -F BDE is higher than that determined by Zare and coworkers 26,27 and that the reaction of Sr + SF 5 f SrF + SF 4 may play a role. Our predicted value for the exothermicity of this reaction is -89.9 ( 4 kcal/mol at 298 K (using experimental values 14 for the heats of formation of Sr and SrF), consistent with the maximum observed in the chemiluminescence corresponding to 87.2 kcal/mol.…”

Section: Douglas-kroll-hess(dkh)hamiltonianforsomemolecules 51-53supporting

confidence: 92%

Bond Dissociation Energies in Second-Row Compounds

et al. 2008

View full text Add to dashboard Cite

Heats of formation at 0 and 298 K are predicted for PF3, PF5, PF3O, SF2, SF4, SF6, SF2O, SF2O2, and SF4O as well as a number of radicals derived from these stable compounds on the basis of coupled cluster theory [CCSD(T)] calculations extrapolated to the complete basis set limit. In order to achieve near chemical accuracy (+/-1 kcal/mol), additional corrections were added to the complete basis set binding energies based on frozen core coupled cluster theory energies: a correction for core-valence effects, a correction for scalar relativistic effects, a correction for first-order atomic spin-orbit effects, and vibrational zero-point energies. The calculated values substantially reduce the error limits for these species. A detailed comparison of adiabatic and diabatic bond dissociation energies (BDEs) is made and used to explain trends in the BDEs. Because the adiabatic BDEs of polyatomic molecules represent not only the energy required for breaking a specific bond but also contain any reorganization energies of the bonds in the resulting products, these BDEs can be quite different for each step in the stepwise loss of ligands in binary compounds. For example, the adiabatic BDE for the removal of one fluorine ligand from the very stable closed-shell SF6 molecule to give the unstable SF5 radical is 2.8 times the BDE needed for the removal of one fluorine ligand from the unstable SF5 radical to give the stable closed-shell SF4 molecule. Similarly, the BDE for the removal of one fluorine ligand from the stable closed-shell PF3O molecule to give the unstable PF2O radical is higher than the BDE needed to remove the oxygen atom to give the stable closed-shell PF3 molecule. The same principles govern the BDEs of the phosphorus fluorides and the sulfur oxofluorides. In polyatomic molecules, care must be exercised not to equate BDEs with the bond strengths of given bonds. The measurement of the bond strength or stiffness of a given bond represented by its force constant involves only a small displacement of the atoms near equilibrium and, therefore, does not involve any reorganization energies, i.e., it may be more appropriate to correlate with the diabatic product states.

show abstract

Section: Douglas-kroll-hess(dkh)hamiltonianforsomemolecules 51-53supporting

confidence: 92%

Bond Dissociation Energies in Second-Row Compounds

et al. 2008

View full text Add to dashboard Cite

show abstract

“…[3][4][5] The conventional value for ⌬ f H 298°͑ SF 5 ͒ is Ϫ912.5Ϯ13.4 kJ/mol, 4 and is based primarily upon the upper bound D 0°͑ SF 5 -F͒р381.2Ϯ13.4 kJ/mol determined from studies of the chemiluminescence resulting from reactions between metastable metal atoms ͑Ca* and Sr*͒ and SF 6 ͓reaction ͑2͔͒ and using D 0°͑ Sr-F͒ϭ535.6Ϯ8.4 kJ/mol and D 0°͑ Ca-F͒ ϭ531.8Ϯ8.4 kJ/mol, 27,39 M*͑ 3 P ͒ϩSF 6 →MF*ϩSF 5 . ͑2͒…”

Section: G Bond Energy D(sf 5 -F)mentioning

confidence: 99%

“…Both of the newer papers 5,6 have noted that different results were obtained using calcium atoms and strontium atoms. 27 No explanations have been offered for this apparent inconsistency. There is also the suggestion 5 that some of the chemiluminescence arose from secondary chemistry such as reaction ͑3͒, involving ground SrϩSF 5 →SrFϩSF 4 ͑3͒ state metal atoms.…”

Section: G Bond Energy D(sf 5 -F)mentioning

confidence: 99%

Structure and thermochemistry of sulfur fluorides SFn (n=1–5) and their ions SF+n (n=1–5)

Irikura¹

1995

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…At electric field-to-gas density ratios, ElIN, close to the critical value where a growth in the net ionization of the gas becomes possible, the mean electron energies in an SF 6 discharge are theoretically estimated [48][49][50] to be between 5 and 10 eV. Thus from a consideration of the known ionization, attachment, and bond dissociation energies [51][52][53][54][55][56] of SF 6 , the initial step in the decomposition is presumed to involve the energetically favorable electron impact dissociation processes leading to various ion and neutral fragments, e-g., e +SF 6 -SF +(6-x)F, x<5.…”

Section: Possible Mechanisms For Oxyfluoride Formationmentioning

confidence: 99%

Production rates for oxyfluorides SOF2, SO2F2, and SOF4 in SF6 corona discharges

Brunt¹

1985

J. RES. NATL. BUR. STAN.

108

View full text Add to dashboard Cite

The most abundant, long-lived stable gaseous species generated by corona discharges in SF 6 gas containing trace levels of 0, and H,0 are the oxyfluorides SOF,, SOF, and SOF 4 . Absolute energy and charge rates-ofproduction of these and the minor products SO,, OCS, and CO2 have been measured at different total gas pressures from 100 kPa to 300 kPa and for discharges of different current, power, and polarity. Oxyfluoride yields for SF6/02 mixtures containing up to 10% 0, have also been measured. The results indicate that oxyfluoride production is not controlled by the concentrations of either 0, or H,0 at levels below about I%, and the rate controlling factor is the dissociation rate of SF 6 in the discharge. The discharge current and time dependence of the production rates are discussed in terms of gas-phase mechanisms that have been proposed to explain previous observations of electrical, thermal, and laser-induced decomposition of SF 6 and SFs/O, mixtures. Upper limits on the total SF 6 decomposition rate in low-current discharges have been estimated. Details of the chemical analysis procedures are given, and application of the results to the design of chemical diagnostics for SF 6 -insulated, high-voltage apparatus is discussed.

show abstract

Stepwise bond dissociation energies in sulfur hexafluoride

Cited by 102 publications

References 2 publications

Bond Dissociation Energies in Second-Row Compounds

Bond Dissociation Energies in Second-Row Compounds

Structure and thermochemistry of sulfur fluorides SFn (n=1–5) and their ions SF+n (n=1–5)

Production rates for oxyfluorides SOF2, SO2F2, and SOF4 in SF6 corona discharges

Contact Info

Product

Resources

About