Interpretation of the charge and energy changes in two nucleophilic displacement reactions

Bader, R. F. W.; Duke, A. J.; Messer, R. R.

doi:10.1021/ja00804a028

Cited by 57 publications

(13 citation statements)

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“…Parker has drawn attention to the caution which should be exercised in any attempt to extract such information from solution measurements of specific rates (1). Quantum mechanical calculations of portions of the intrinsic energy surfaces of displacement reactions of type [l] have in fact indicated the presence of what are, in some instances, quite substantial energy barriers (8,9). The gas-phase (single temperature) measurements reported here can also provide some indication of the possible presence and magnitude of these intrinsic activation energies.…”

Section: Discussionmentioning

confidence: 51%

“…For the reactions of F-and CN-with CH3F comparisons can be with the barrier heights computed by Dedieu and Veillard (8) and Bader el rrl. (9). Within the uncertainty of the empirical correlation and its extrapolation the accord between theory and experiment is reasonable.…”

Section: Their Reuctrcrly and Its Variation M*ii/z Heat O/ Reactionmentioning

confidence: 65%

“…These results prompted Won and Willi to reopen the discussion of the mechanism of the S,2 reactions of methyl halides with nucleophiles in solution (6). Later measurements ( 5 , 7) revealed several slow S,2 reactions and suggested that energy barriers rather than orientation or steric effects were the important rate controlling factors as had been predicted in several molecular orbital calculations (8,9).…”

Section: Introductionmentioning

confidence: 93%

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Gas-phase reactions of anions with halogenated methanes at 297 ± 2 K

Tanaka¹,

Mackay²,

Payzant³

et al. 1976

Can. J. Chem.

211

116

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. Can. J. Chem. 54, 1643 (1976). The rate constants for a number of exothermic displacement (S,,2) reactions of the type X-+ CH3Y -Y + CH3X where X-= H-, 0 -, C-, F-, S-, CI-, OH-, C,-, C N -, SH-, S,-, C,H-, NHz-. NO,-, C H F -, CH,CI-, C H , B r , C H 3 0 -, CH,S-. and C H , N H and Y = F, CI, and Br, have been measured in the gas phase at 297 f 2 K using the flowing afterglow technique. These gas-phase measurements provided an opportunity to determine the intrinsic nucleophilic reactivity of 'nude' anions and hence to assess the role of solvation in the kinetics of S,,2 reactions proceeding in solution. Comparisons of the experimental rate constants with rate constants calculated using classical theories of capture indicate that several displacement reactions may possess large inrrin.sic energies of activation, E, >> 2 kcal mol-I.Correlations were found between apparent activation energies and the heats of reaction. These correlations provided a convenient classification of the various anion nucleophiles. Displacement was observed to compete with proton transfer in reactions involving nucleophiles of high intrinsic basicity and with hydrogen atom transfer and Hz' transfer in the reactions of the 0-radical anion.

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Section: Discussionmentioning

confidence: 51%

Section: Their Reuctrcrly and Its Variation M*ii/z Heat O/ Reactionmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 93%

See 1 more Smart Citation

Gas-phase reactions of anions with halogenated methanes at 297 ± 2 K

Tanaka¹,

Mackay²,

Payzant³

et al. 1976

Can. J. Chem.

211

116

View full text Add to dashboard Cite

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“…Thus, from the sign of AT(A) in eq. 5, one may determine whether a given fragment is stabilized or destabilized in the formation This approach has been previously applied t o the charge redistributions and energy changes associated with the formation of the first-row hydrides (5), and to the corresponding changes associated with nucleophilic displacement reactions (12). The attractive potential interaction of the charge density in fragment (A) with all of the nuclei in a system V'(A) may be written as a sum over the separate nuclear contributions.…”

Section: P (~H >mentioning

confidence: 99%

Virial Partitioning of Charge Distributions and Properties of Diatomic Hydrides; NaH ↔ HCl

Bader¹,

Messer²

1974

Can. J. Chem.

Self Cite

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. Can. J. Chem. 52, 2268Chem. 52, (1974 The virial partitioning method is applied to the ground states of the AH diatomic hydrides (A = Na, Mg, Al, Si, P, S, C1) in their neutral and charged forms. This is a spatial partitioning of a molecular system, the partitioning surfaces, which in this instance divide each molecule into an (A) and an (H) fragment, bcing determined by the topographical features of the electronic charge distribution. The kinetic and potential energies of the virial fragments are well-defined quantities and in addition, satisfy the quantum mechanical virial relationship. Most important, virial fragments faithfully reflect the chemistry of the individual elemental components of molecular systems, the fragments and their properties remaining nearly constant or changing when in different systems, in accordance with chemical expectations.The populations of (H) in combination with (A) are used to order the first-and second-row elements (neutral and charged) in their abilities to abstract or donate charge relative to hydrogen. This ordering is of general interest as the population of (H) in A H changes little on passage to the general (most stable) polyatomic AH,,. The virial equations are used to relate the kinetic energy of binding in AH to the changes in the potential energies and total energies of each fragment. One finds, in comparison of first-and second-row results, that the nature of the most important stabilizing interactions in the formation of AH change in a similar manner across the two rows of elements, but the change in the second-row set occurs two members to the right with respect to the first-row set.R. F. W. BADER et R. R. MESSER. Can. J. Chem. 52, 2268Chem. 52, (1974 On applique la methode de partition virielle aux formes neutres et chargtes des Ctats fondamentaux des hydrures diatomiques AH (A = Na, Mg, Al, Si, P, S, C1). C'est une partition spatiale d'un systeme moleculaire, la partition de surfaces, qui dans cette circonstance divise chaque molecule en un fragment (A) et un fragment (H), determines par les caracthes topographiques de la distribution de la charge electroniq?le. Les energies cinetiques et potentielles des fragments viriels sont des quantitis bien definies et de plus satisfont la micanique quantique virielie. Plus jmportant encore, les fragments viriels refletent fidelement la chimie des composants elementaires individuels des systemes moleculaires, les fragments et leurs propriktes restent presque constants ou changent avec les diffkrents systemes conformement aux previsions chimiques.On utilise ies populations de (H) en combinaison avec (A) pour classer les eltments de la premiere et de la deuxieme rangee (neutres et charges) selon leur habilitt par rapport a l'hydrogene d'arracher ou donner la charge. Ce classenlent est d'un interet general sachant que la population de (H) dans A H change peu lorsque I'on passe au produit polyatomique general (plus stable) AH,,. On utilise les equations virielles pour etablir un rapport entre I'energie cinitique de liaison...

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“…Bimolecular nucleophilic substitution reactions ( S N 2) have been extensively investigated experimentally, both in solution1–3 and in the gas phase,4–29 and theoretically 30–41. The majority of these studies involve anionic nucleophiles and leaving groups, whereas S N 2 reactions involving cationic nucleophiles have received far less attention.…”

Section: Introductionmentioning

confidence: 99%

Fluorinated methyl cation (CF3+, CFH2+)-alkyl nitrile cluster ions

2000

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Ion-molecule reactions of CF(3)(+) or CFH(2)(+) with an acetonitrile-butyronitrile mixture yield product cluster ions in which the two neutral molecules are associated with the cation. The structures of the ion-molecule product ions were investigated by collision-induced dissociation in a multi-quadrupole mass spectrometer. The cluster ions fragment by loss of one neutral alkyl nitrile. The abundance of the fragment ions shows an unexpected inverse correlation with the proton affinity of the alkyl nitrile. This result is inconsistent with the formation of a simple cation-bound dimeric cluster containing two alkyl nitrile molecules and a fluorinated methyl cation; instead, a pair of non-symmetrical dimeric complexes, separated by a large internal barrier, is indicated. This result is analogous to that observed for the putative methyl cation-bound heterodimer of acetonitrile and butyronitrile. Collision energy dependence studies and ab initio calculations suggest that the dimeric complexes are formed in potential energy wells located in an approximately symmetrical potential energy surface. Quasi-equilibrium theory calculations were used in order to obtain additional insights into the experimental data.

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Interpretation of the charge and energy changes in two nucleophilic displacement reactions

Cited by 57 publications

References 0 publications

Gas-phase reactions of anions with halogenated methanes at 297 ± 2 K

Gas-phase reactions of anions with halogenated methanes at 297 ± 2 K

Virial Partitioning of Charge Distributions and Properties of Diatomic Hydrides; NaH ↔ HCl

Fluorinated methyl cation (CF3+, CFH2+)-alkyl nitrile cluster ions

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