Competitive Threshold Collision-Induced Dissociation:  Gas-Phase Acidities and Bond Dissociation Energies for a Series of Alcohols

1999 ◽  
Vol 103 (35) ◽  
pp. 6911-6920 ◽  
Author(s):  
Vincent F. DeTuri ◽  
Kent M. Ervin

2005 ◽  
Vol 83 (11) ◽  
pp. 2013-2019 ◽  
Author(s):  
Changtong Hao ◽  
Thomas M Gilbert ◽  
Lee S Sunderlin

The gas-phase strengths of the SO3—X- bonds (X = Cl, Br, and I) have been determined to be 222 ± 13, 179 ± 11, and 161 ± 9 kJ/mol, respectively, by measuring thresholds for collision-induced dissociation in a flowing afterglow-tandem mass spectrometer. An upper limit of D(SO3—F–) ≤ 488 ± 19 kJ/mol was also determined. The periodic trends in the halide affinities of SO3 closely parallel those for SO2 and other Lewis acids. Bond strengths computed using the B3LYP, MP2, QCISD(T), and other models with several basis sets are generally lower than experiment.Key words: bond dissociation energies, computational chemistry, Lewis acids, superacids, halide affinities.





2018 ◽  
Vol 429 ◽  
pp. 212-226 ◽  
Author(s):  
Ashley S. McNeill ◽  
Can Cui ◽  
Sean R. Miller ◽  
Michele L. Stover ◽  
Maranda Burns ◽  
...  


2010 ◽  
Vol 1264 ◽  
Author(s):  
Cláudia C. L. Pereira ◽  
Joaquim Marçalo ◽  
John K. Gibson

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.



1993 ◽  
Vol 123 (3) ◽  
pp. 171-185 ◽  
Author(s):  
Thuy Thanh Dang ◽  
Edwin L. Motell ◽  
Michael J. Travers ◽  
Eileen P. Clifford ◽  
G. Barney Ellison ◽  
...  


1990 ◽  
Vol 68 (10) ◽  
pp. 1714-1718 ◽  
Author(s):  
Frederick G. Bordwell ◽  
John A. Harrelson Jr

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.





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