Anchoring the Gas-Phase Acidity Scale from Hydrogen Sulfide to Pyrrole. Experimental Bond Dissociation Energies of Nitromethane, Ethanethiol, and Cyclopentadiene

2015 ◽  
Vol 119 (28) ◽  
pp. 7169-7179 ◽  
Author(s):  
Kent M. Ervin ◽  
Alex A. Nickel ◽  
Jerry G. Lanorio ◽  
Surja B. Ghale
Keyword(s):  
Hydrogen Sulfide ◽  
Gas Phase ◽  
Bond Dissociation Energies ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
Gas Phase Acidity ◽  
Acidity Scale

Summary of gas phase acidity measurements involving acids AH. Entropy changes in proton transfer reactions involving negative ions. Bond dissociation energies D(A—H) and electron affinities EA(A)

1978 ◽  
Vol 56 (1) ◽  
pp. 1-9 ◽  
Author(s):  
J. B. Cumming ◽  
P. Kebarle
Keyword(s):  
Proton Transfer ◽  
Gas Phase ◽  
Negative Ions ◽  
Bond Dissociation Energies ◽  
Electron Affinities ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
Entropy Changes ◽  
Gas Phase Acidity ◽  
Proton Transfer Reactions

The complete ladder of ΔG10 determinations obtained from measurements of some 110 gas phase proton transfer equilibria A1− + A2H = A1H + A2− involving some 60 acids AH and connecting to the standard acid HCl is given. Evaluation of the entropy changes leads to values for the deprotonation energies ΔHD0 and ΔGD0 (at room temperature) corresponding to the gas phase process AH = A− + H+; ΔHD0 = D(A—H) − EA(A) + 313.6 kcal/mol. Comparison of the present data with literature determinations of the bond dissociation energies and electron affinities shows agreement within 2 kcal/mol. Some experimentally determined entropy changes ΔS10 are compared with the theoretically calculated values.

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

Cation−Ether Complexes in the Gas Phase:  Bond Dissociation Energies and Equilibrium Structures of Li+[O(CH3)2]x,x= 1−4

1996 ◽  
Vol 100 (5) ◽  
pp. 1605-1614 ◽  
Author(s):  
Michelle B. More ◽  
Eric D. Glendening ◽  
Douglas Ray ◽  
David Feller ◽  
P. B. Armentrout
Keyword(s):  
Gas Phase ◽  
Bond Dissociation Energies ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
Equilibrium Structures
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