The 2-norbornyl cation is a π-complex, not a σ-bridged, nonclassical species: an AIM study

Muchall, Heidi M.

doi:10.1016/s0166-1280(98)00625-3

Cited by 32 publications

(40 citation statements)

References 22 publications

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“…Table 2 shows some geometrical information along with r b , ∇ 2 r b , E at (W), q(W), SE at (C1-C3), e, |l 1 |/l 3 of the bond critical points 1-3, 5 and 6, and DI of their corresponding atomic pairs of the species 3-GS, 4-GS, 3-TS and 4-TS. Figure 5 shows the molecular graphs of the 2-norbornyl cation 36,38,39 and oxabicycloheptanyl cation. Both follow the Poincaré-Hopf relationship.…”

Section: Topological Study Of the Firstmentioning

confidence: 99%

“…The quantum theory of atoms in molecules 34,35 (QTAIM) has been used to study the electronic nature of norbornyl cation and derivatives. [36][37][38][39] In this work, we applied QTAIM to reevaluate the first step of two unassisted nucleophilic solvolysis: [R-OH 2 ] + → R + + H 2 O, where R is 2-endo/exonorbornyl and 2-endo/exo-oxabicycloheptanyl moieties, that were previously studied by Schleyer and co-workers 33 by using molecular orbital theory. Certainly, different leaving groups would lead to different carbocation character to the transition state structure of the studied molecules in gas phase, but our work is restricted to water as leaving group for comparison reasons with the work of Schleyer and collaborators.…”

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confidence: 99%

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Topological study of the first step of nucleophilically unassisted solvolysis of protonated 2-endo/exo-norbornanol and protonated 2-endo/exo-oxabicycloheptanol

Firme¹

2012

J. Braz. Chem. Soc.

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A assistência da deslocalização de elétrons sigma ou assistência anquimérica dos elétrons sigma explica grandes diferenças de velocidade na solvólise de 2-exo-e 2-endo-norbornilp-bromobenzenosulfonatos. Este estudo foi anteriormente analisado pela teoria dos orbitais moleculares em fase gás. Ao revisitar este antigo problema a partir da teoria quântica de átomos em moléculas (QTAIM), novas informações sobre essas reações foram obtidas. Os resultados de QTAIM mostram que, na primeira etapa da solvólise não assistida nucleofilicamente dos alcoóis protonados 2-exo-norbornanol e 2-endo-norbornanol, ambas as reações são anquimericamente assistidas pela participação de elétrons sigma. Similarmente, na primeira etapa da solvólise não assistida nucleofilicamente dos álcoois protonados 2-endo-oxabicicloheptanol e 2-exooxabicicloheptanol, os resultados de QTAIM mostram que ambas as reações são anquimericamente assistidas: a primeira a partir da participação da ligação sigma C-O e de pares de elétrons isolados do oxigênio e a última a partir da participação da ligação sigma C1-C2. The assistance of s electron delocalization or anchimeric assistance of s electrons accounts for the large rate differences in the solvolysis of 2-exo-and 2-endo-norbornylp-bromobenzenesulfonates. This study was formerly analyzed by molecular orbital theory in gas phase. By revisiting this old problem from the quantum theory of atoms in molecules (QTAIM), new information on these reactions was obtained. The QTAIM results show that, in the first step of the nucleophilically unassisted solvolysis of protonated 2-exo-norbornanol and of protonated 2-endo-norbornanol, both reactions are anchimerically assisted by sigma bond participation. Similarly, in the first step of the nucleophilically unassisted solvolysis of protonated 2-endooxabicycloheptanol and of protonated 2-exo-oxabicycloheptanol, the QTAIM results show that both reactions are anchimerically assisted: the former from sigma bond participation from O-C bonds and valence shell electron participation from oxygen atom and the latter from sigma bond participation from C1-C2 bond.

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Section: Topological Study Of the Firstmentioning

confidence: 99%

mentioning

confidence: 99%

Topological study of the first step of nucleophilically unassisted solvolysis of protonated 2-endo/exo-norbornanol and protonated 2-endo/exo-oxabicycloheptanol

Firme¹

2012

J. Braz. Chem. Soc.

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“…Our recent computational studies on a number of cations, including 2-norbornyl, established that coordination based on the number of bond paths -as defined in a QTAIM 6 molecular graph -terminating at a nucleus in any species -cation, carbanion, radical, or carbene -should be used as the criterion of hyper-coordination and hyper-valency. 7,8,9,10 A QTAIM treatment precludes interpretational bias of the nature of bonding based on qualitative evidence such as interatomic distances. We argued that this approach should be used regardless of the nature of the intermediate to obviate the confusion and inaccuracies associated with arbitrarily using indicators such as dashed lines, dotted lines, cross-hatched lines, hollow tubes, and solid tubes in structural formulas.…”

Section: Ch 3mentioning

confidence: 99%

QTAIM-DI-VISAB computational study on the so-called nonclassical bicyclobutonium cation

Poulsen¹

2008

Arkivoc

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This paper is dedicated to Ted Sorensen for his contributions to chemistry on the occasion of his 75 th birthday Abstract QTAIM-DI-VISAB analyses at the CCSD and B3PW91 levels were used to characterize the bonding of the cyclopropylcarbinyl (1) and the so-called 'nonclassical' bicyclobutonium and 1-methylbicyclobutonium cations, 2 and 3 as well as the transition state for rearrangement of 1 to 2. These analyses involved obtaining QTAIM molecular graphs and delocalization indexes (DIs) for pairs of atoms that were correlated with the proximities of atomic basins (VISAB). This study showed that the supposed nonclassical bicyclobutonium and 1-methylbicyclobutonium cations do not exhibit penta-coordinate carbons at their equilibrium geometries as has been claimed. Both species are best described as distorted cyclobutyl cations that exhibit a single ring critical point in the topology of the charge density.

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“…This DFT level was chosen because we established earlier that it yielded results that mirrored those obtained with MP2(full) with the same basis set, but at a much lower computational cost. 7,8 The intrinsic coordinate (IRC) for the rearrangement of 9 to 11 was mapped with sixty points on each side of TS(9-11) to ensure it led to 9 and 11. Zero point energies (ZPVE) were also evaluated at the same level but not scaled.…”

Section: Computational Detailsmentioning

confidence: 99%

“…1,2 The closely related nortricyclyl-3-carbinyl brosylate (4-OBs) also gave the same products. 3 On the other hand, tricyclo[3.2.1.0 2,7 ]octan-4-yl brosylate (5-OBs) gave only 5-OAc, 6-OAc, and a trace of 7-OAc. 3 Under relatively mild conditions (HOAc, NaOAc, 50 o ), 5-OBs yielded 5-OAc, 6-OAc, a trace of 7-OAc, and 8-OAc.…”

Section: Introductionmentioning

confidence: 99%

A density functional theory study on the rearrangements of the 6-tricyclo[3.2.1.02,4]octyl cation and its isomers: a walk on the C8H11+ potential energy surface and a peek at molecular structures with AIM

Wang¹

2002

Arkivoc

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The 2-norbornyl cation is a π-complex, not a σ-bridged, nonclassical species: an AIM study

Cited by 32 publications

References 22 publications

Topological study of the first step of nucleophilically unassisted solvolysis of protonated 2-endo/exo-norbornanol and protonated 2-endo/exo-oxabicycloheptanol

Topological study of the first step of nucleophilically unassisted solvolysis of protonated 2-endo/exo-norbornanol and protonated 2-endo/exo-oxabicycloheptanol

QTAIM-DI-VISAB computational study on the so-called nonclassical bicyclobutonium cation

A density functional theory study on the rearrangements of the 6-tricyclo[3.2.1.02,4]octyl cation and its isomers: a walk on the C8H11+ potential energy surface and a peek at molecular structures with AIM

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