Applications of the Quantum Theory of Atoms in Molecules in Organic Chemistry – Charge Distribution, Conformational Analysis and Molecular Interactions

Hernández‐Trujillo, Jesús; Cortés‐Guzmán, Fernando; Cuevas, Gabriel

doi:10.1002/9783527610709.ch14

Cited by 4 publications

(2 citation statements)

References 60 publications

(82 reference statements)

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“…Accordingly, δ(H,H‘) provides a measure of the number of electrons shared between the atoms H and H‘. For example, the values of δ(H,H‘) as a function of the H−C−C−H dihedral angle in ethane display the same behavior as that found by Karplus for the corresponding coupling constants that for a number of organic molecules, including polybenzenoid hydrocarbons, the Fermi contact produces a dominant contribution to the 3 J HH ‘ values; hence, this property mainly results from the coupling of nuclear spins mediated by the electronic spins with this dominant term of the s-type orbitals at the nuclear positions.…”

Section: Introductionsupporting

confidence: 75%

Experimental and Theoretical Analysis of Vicinal and Long-Range Proton−Proton Coupling Constants for Anthracene Derivatives

2007

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We studied vicinal and long-range coupling constants for 9-anthracene derivatives, e.g., Br, CN, CHO, NO2, CH2Cl, CH2OH, and OCH3. We performed the accurate measurements using modified J doubling in the frequency domain, even for the smallest couplings immersed within the line width. Density functional theory allowed us to reproduce and exhaustively analyze the physical contributions to the values of these spectroscopic parameters. The theory of atoms in molecules defines a delocalization index that correlates linearly with vicinal and long-range coupling constants when they are grouped in terms of the number of bonds between the coupled nuclei. An exception to this behavior is obtained for 4J(H4,H10) values, which have a negative Fermi contact and the largest delocalization index for each molecule. This observation can be explained by a characteristic "gable roof" arrangement formed by the five nuclei involved in the coupling.

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Section: Introductionsupporting

confidence: 75%

Experimental and Theoretical Analysis of Vicinal and Long-Range Proton−Proton Coupling Constants for Anthracene Derivatives

2007

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“…Other approaches are based on examining the shape of localized orbitals, calculated using some ultimately arbitrary localization procedure. − In contrast to these methods, the calculation of the population covariances in the QTAIM basins, known as localization and delocalization indices (DIs), gives a direct, quantitative measure of interatomic electron delocalization. DIs have found ample use in the literature, with applications such as the calculation of bond orders and the position of electron pairs, − NMR coupling constants, and aromaticity, , to name a few. Some of us recently used DIs to detect delocalization error from density functional approximations in halogen-bonded systems …”

Section: Introductionmentioning

confidence: 99%

Quantitative Electron Delocalization in Solids from Maximally Localized Wannier Functions

Otero-de-la-Roza

Pendás

Johnson

2018

J. Chem. Theory Comput.

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Electron delocalization is the quantum-mechanical principle behind chemical concepts such as aromaticity, resonance, and bonding. A common way to measure electron delocalization in the solid state is through the visualization of maximally localized Wannier functions, a method similar to using localized orbitals in molecular quantum chemistry. Although informative, this method can only provide qualitative information and is essentially limited by the arbitrariness in the choice of orbital rotation. Quantitative orbital-independent interatomic delocalization indices can be calculated by integration inside of atomic regions of probability densities obtained from the system's wave function. In particular, Bader's delocalization indices are very informative, but typically expensive to calculate. In this article, we present a fast method to obtain the localization and delocalization indices in a periodic solid under the plane-wave/pseudopotential approximation. The efficiency of the proposed method hinges on the use of grid-based atomic integration techniques and maximally localized Wannier functions. The former enables the rapid calculation of all atomic overlap integrals required in the construction of the delocalization indices. The latter allows discarding the overlaps between maximally localized Wannier functions whose centers are far enough apart. Using the new method, all localization and delocalization indices in solids with dozens of atoms can be calculated in hours on a desktop computer. Illustrative examples are presented and studied: some simple and molecular solids, polymeric nitrogen, intermolecular delocalization in 10 phases of ice, and the self-ionization of ammonia under pressure. This work is an important step toward the quantitative description of chemical bonding in solids under pressure.

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Substituent‐Controlled Reactivity in the Nazarov Cyclisation of Allenyl Vinyl Ketones

Marx

Stoddard

Heverly‐Coulson

et al. 2011

Chemistry A European J

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Alkyl substitution α to the ketone of an allenyl vinyl ketone enhances Nazarov reactivity by inhibiting alternative pathways involving the allene moiety and through electron donation and/or steric hindrance. This substitution pattern also accelerates Nazarov cyclisation by increasing the population of the reactive conformer and by stabilising the oxyallyl cation intermediate. Furthermore, α substitution by an alkyl group does not alter the regioselectivity of interrupted Nazarov reactions when the oxyallyl cation intermediate is intercepted by addition of an oxygen nucleophile, or by [4+3] cyclisation with acyclic dienes. The regioselectivity of the Nazarov process for allenyl vinyl ketones was determined to be a result of an electronic bias in the oxyallyl cation intermediate. Computational data are consistent with this observation.

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Applications of the Quantum Theory of Atoms in Molecules in Organic Chemistry – Charge Distribution, Conformational Analysis and Molecular Interactions

Cited by 4 publications

References 60 publications

Experimental and Theoretical Analysis of Vicinal and Long-Range Proton−Proton Coupling Constants for Anthracene Derivatives

Experimental and Theoretical Analysis of Vicinal and Long-Range Proton−Proton Coupling Constants for Anthracene Derivatives

Quantitative Electron Delocalization in Solids from Maximally Localized Wannier Functions

Substituent‐Controlled Reactivity in the Nazarov Cyclisation of Allenyl Vinyl Ketones

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