Ab initio studies of the gas-phase thermodynamic properties and bond dissociation energies for haloethanes and halomethyl radicals

2001 ◽  
Vol 3 (5) ◽  
pp. 811-818 ◽  
Author(s):  
Adriana C. Olleta ◽  
Silvia I. Lane
Keyword(s):  
Thermodynamic Properties ◽  
Ab Initio ◽  
Gas Phase ◽  
Bond Dissociation Energies ◽  
Bond Dissociation ◽  
Dissociation Energies

Thermochemistry of Elementary Actinide Sulfide Molecules: A Gas-Phase Study of Curium Sulfide

2010 ◽  
Vol 1264 ◽  
Author(s):  
Cláudia C. L. Pereira ◽  
Joaquim Marçalo ◽  
John K. Gibson
Keyword(s):  
Gas Phase ◽  
Bond Dissociation Energies ◽  
Gas Phase Reactions ◽  
General Applicability ◽  
Molecular Systems ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
Phase Study ◽  
Fundamental Understanding ◽  
Actinide Ions

AbstractExperiments to explore the reactivity and thermochemistry of elementary transuranium sulfide molecules have been initiated to expand the basis for a fundamental understanding of actinide bonding, and to enable the development of advanced theoretical methodologies which will be of general applicability to more complex molecular systems. Bimolecular gas-phase reactions between transuranium actinide ions and neutral reagents are employed to obtain thermochemical information. The initial actinide sulfide studies have focused on obtaining the 298 K bond dissociation energy for the CmS+ ion, D[Cm+-S] = 475±37 kJ mol-1; from this result and an estimate of IE[CmS] ≈ IE[CmO] + 0.5 eV, we obtain D[Cm-S] = 563±64 kJ mol-1. The bond dissociation energies, D[Cm+-S] and D[Cm-S] are approximately 200 kJ mol-1 and 150 kJ mol-1 lower than for the corresponding oxides, CmO+ and CmO. The nature of the bonding in the CmS+ ion appears to be generally similar to that in other oxophilic metal sulfides. Comparisons with previous bond dissociation energies reported for ThS and US may suggest a difference in the An-S bonds for these early actinide sulfides as compared with CmS.

Acidities and homolytic bond dissociation energies of the αC—H bonds in ketones in DMSO

1990 ◽  
Vol 68 (10) ◽  
pp. 1714-1718 ◽  
Author(s):  
Frederick G. Bordwell ◽  
John A. Harrelson Jr
Keyword(s):  
Gas Phase ◽  
Radical Cations ◽  
Bond Dissociation Energies ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
Oxidation Potentials ◽  
Stabilization Energies ◽  
Conjugate Bases

Equilibrium acidities in DMSO are reported for nine cycloalkanones, acetone, acetophenone, and 19 of their α-substituted derivatives. Oxidation potentials in DMSO for the conjugate bases of most of these ketones are also reported. Combination of these EOX(A−) and pKHA values gives estimates of the homolytic bond dissociation energies (BDEs) of the acidic C—H bonds in the ketones. The ΔBDEs, relative to the BDE of CH3-H, or a parent ketone, provide a measure of the radical stabilization energies (RSEs) of the corresponding radicals. The effects of successive α-Me and α-Ph substitutions on RSEs, relative to those of CH3COCH2-H or PhCOCH2-H, are similar to those reported in the gas phase for methane. The RSE for the MeĊHCOPh radical, relative to CH3• is 17 kcal/mol, which is smaller than the sum of the RSEs of the MeCH2• and PhCOCH2• radicals relative to CH3• (7 + 12 = 19), contrary to the prediction of the captodative postulate. When G in PhCOCH2G is PhCO, CH3CO, or CN the ΔBDEs (relative to PhCOCH2-H) are 0, 1, and 3 respectively; for MeCOCH2SO2Ph, PhCOCH2SO2Ph, and PhCOCH2NMe3+ the ΔBDEs are −5, −2, and −4, respectively. The BDEs in C5, C6, C7, C8, C10, and C12 cycloalkanones are within ±2.5 kcal/mol of that of 3-pentanone. Acetophenones bearing meta or para substituents all have BDEs of 93-94 kcal/mol. Ketone radical cations, [RCOR′]+•, appear to be superacids with estimated [Formula: see text] values below −25. Keywords: acidities, bond dissociation energies, ketones.

ChemInform Abstract: Bond Dissociation Energies in DMSO Related to the Gas Phase.

ChemInform ◽  
2010 ◽  
Vol 23 (16) ◽  
pp. no-no
Author(s):  
F. G. BORDWELL ◽  
J.-P. CHENG ◽  
G.-Z. JI ◽  
A. V. SATISH ◽  
X. ZHANG
Keyword(s):  
Gas Phase ◽  
Bond Dissociation Energies ◽  
Bond Dissociation ◽  
Dissociation Energies
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