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  1. Article ; Online: How Different are the Diamagnetic and Paramagnetic Contributions to Off-Nucleus Shielding in Aromatic and Antiaromatic Rings?

    Karadakov, Peter B

    Chemphyschem : a European journal of chemical physics and physical chemistry

    2023  Volume 24, Issue 9, Page(s) e202300038

    Abstract: The spatial variations in the diamagnetic and paramagnetic contributions to the off-nucleus isotropic shielding, ...

    Abstract The spatial variations in the diamagnetic and paramagnetic contributions to the off-nucleus isotropic shielding,
    Language English
    Publishing date 2023-03-09
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2025223-7
    ISSN 1439-7641 ; 1439-4235
    ISSN (online) 1439-7641
    ISSN 1439-4235
    DOI 10.1002/cphc.202300038
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Aromaticity in the Electronic Ground and Lowest Triplet States of Molecules with Fused Thiophene Rings.

    Cummings, Edward / Karadakov, Peter B

    Chemistry (Weinheim an der Bergstrasse, Germany)

    2024  Volume 30, Issue 20, Page(s) e202303724

    Abstract: Analysis of the variations of the off-nucleus isotropic magnetic shielding, ... ...

    Abstract Analysis of the variations of the off-nucleus isotropic magnetic shielding, σ
    Language English
    Publishing date 2024-02-21
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1478547-X
    ISSN 1521-3765 ; 0947-6539
    ISSN (online) 1521-3765
    ISSN 0947-6539
    DOI 10.1002/chem.202303724
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  3. Article ; Online: The Effect of Hydrogenation on the Contest between Aromaticity and Antiaromaticity in Norcorrole.

    Karadakov, Peter B / Riley, Tom

    Chemistry (Weinheim an der Bergstrasse, Germany)

    2023  Volume 29, Issue 12, Page(s) e202203400

    Abstract: Magnetic shielding studies demonstrate that successive hydrogenation of ... ...

    Abstract Magnetic shielding studies demonstrate that successive hydrogenation of Ni
    Language English
    Publishing date 2023-01-18
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1478547-X
    ISSN 1521-3765 ; 0947-6539
    ISSN (online) 1521-3765
    ISSN 0947-6539
    DOI 10.1002/chem.202203400
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Norcorrole: Aromaticity and Antiaromaticity in Contest.

    Karadakov, Peter B

    Organic letters

    2020  Volume 22, Issue 21, Page(s) 8676–8680

    Abstract: Magnetic shielding studies demonstrate that nickel norcorrole (NiNc) and norcorrole ( ... ...

    Abstract Magnetic shielding studies demonstrate that nickel norcorrole (NiNc) and norcorrole (H
    Language English
    Publishing date 2020-10-26
    Publishing country United States
    Document type Journal Article
    ISSN 1523-7052
    ISSN (online) 1523-7052
    DOI 10.1021/acs.orglett.0c03254
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Excited-State Aromaticity Reversals in Naphthalene and Anthracene.

    Karadakov, Peter B / Al-Yassiri, Muntadar A H

    The journal of physical chemistry. A

    2023  Volume 127, Issue 14, Page(s) 3148–3162

    Abstract: Aromaticity reversals between the electronic ground ( ... ...

    Abstract Aromaticity reversals between the electronic ground (S
    Language English
    Publishing date 2023-04-03
    Publishing country United States
    Document type Journal Article
    ISSN 1520-5215
    ISSN (online) 1520-5215
    DOI 10.1021/acs.jpca.3c00485
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Magnetic Shielding Analysis of Bonding in [1.1.1]Propellane.

    Karadakov, Peter B / Stewart, Ben / Cooper, David L

    The journal of physical chemistry. A

    2023  Volume 127, Issue 4, Page(s) 861–869

    Abstract: The bonding in [1.1.1]propellane, bicyclo[1.1.0]butane, bicyclo[1.1.1]pentane, tetrahedrane, and cyclopropane is investigated by analyzing changes in the off-nucleus isotropic magnetic shielding within the space surrounding each of these molecules and, ... ...

    Abstract The bonding in [1.1.1]propellane, bicyclo[1.1.0]butane, bicyclo[1.1.1]pentane, tetrahedrane, and cyclopropane is investigated by analyzing changes in the off-nucleus isotropic magnetic shielding within the space surrounding each of these molecules and, for [1.1.1]propellane, by examining also the diamagnetic and paramagnetic contributions to this shielding. Any shielding arising from the two "exo" sp
    Language English
    Publishing date 2023-01-18
    Publishing country United States
    Document type Journal Article
    ISSN 1520-5215
    ISSN (online) 1520-5215
    DOI 10.1021/acs.jpca.2c06450
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Reassessing the Composition of Hybrid Orbitals in Contemporary VB Calculations.

    Cooper, David L / Penotti, Fabio E / Karadakov, Peter B

    The journal of physical chemistry. A

    2023  Volume 127, Issue 23, Page(s) 4949–4956

    Abstract: Large variations in the ratios between the p and s components of individual hybrid orbitals that have been observed in contemporary ab initio VB calculations are reassessed, and links are established to specific energy terms that drive bond formation. It ...

    Abstract Large variations in the ratios between the p and s components of individual hybrid orbitals that have been observed in contemporary ab initio VB calculations are reassessed, and links are established to specific energy terms that drive bond formation. It is demonstrated that the ratios between the p and s components for individual hybrid orbitals are not indicative of the overall hybridization status of the relevant atom, which exhibits only relatively small variations with the level of theory, irrespective of whether or not non-dynamical and dynamical electron correlation effects are accounted for. An alternative orbital representation that turns out to be far more consistent with the overall hybridization of the relevant atom is examined. The chosen test cases, which can be compared with the classical sp
    Language English
    Publishing date 2023-05-31
    Publishing country United States
    Document type Journal Article
    ISSN 1520-5215
    ISSN (online) 1520-5215
    DOI 10.1021/acs.jpca.3c01857
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Aromaticity reversals and their effect on bonding in the low-lying electronic states of cyclooctatetraene.

    Karadakov, Peter B / Preston, Nicholas

    Physical chemistry chemical physics : PCCP

    2021  Volume 23, Issue 43, Page(s) 24750–24756

    Abstract: Aromaticity reversals and their effect on chemical bonding in the low-lying electronic states of cyclooctatetraene (COT) are investigated through a visual approach which examines the variations in isotropic magnetic shielding in the space surrounding the ...

    Abstract Aromaticity reversals and their effect on chemical bonding in the low-lying electronic states of cyclooctatetraene (COT) are investigated through a visual approach which examines the variations in isotropic magnetic shielding in the space surrounding the molecule. The ground state (S
    Language English
    Publishing date 2021-11-10
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/d1cp04394c
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Can Anti-Aufbau DFT Calculations Estimate Singlet Excited State Aromaticity? Correspondence on "Dibenzoarsepins: Planarization of 8π-Electron System in the Lowest Singlet Excited State".

    Karadakov, Peter B / Saito, Shohei

    Angewandte Chemie (International ed. in English)

    2020  Volume 59, Issue 24, Page(s) 9228–9230

    Abstract: The simple anti-aufbau DFT approach for estimating singlet excited state aromaticity suggested in a recent Communication published in this journal is shown to produce incorrect results because it targets a linear combination of the singlet and triplet ... ...

    Abstract The simple anti-aufbau DFT approach for estimating singlet excited state aromaticity suggested in a recent Communication published in this journal is shown to produce incorrect results because it targets a linear combination of the singlet and triplet configurations involving the HOMO and LUMO rather than the first singlet excited state. If the S
    Language English
    Publishing date 2020-05-08
    Publishing country Germany
    Document type Letter
    ZDB-ID 2011836-3
    ISSN 1521-3773 ; 1433-7851
    ISSN (online) 1521-3773
    ISSN 1433-7851
    DOI 10.1002/anie.202001934
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  10. Article: Magnetic shielding paints an accurate and easy-to-visualize portrait of aromaticity

    Karadakov, Peter B. / VanVeller, Brett

    Chemical communications. 2021 Sept. 21, v. 57, no. 75

    2021  

    Abstract: Chemists are trained to recognize aromaticity semi-intuitively, using pictures of resonance structures and Frost-Musulin diagrams, or simple electron-counting rules such as Hückel's 4n + 2/4n rule. To quantify aromaticity one can use various aromaticity ... ...

    Abstract Chemists are trained to recognize aromaticity semi-intuitively, using pictures of resonance structures and Frost-Musulin diagrams, or simple electron-counting rules such as Hückel's 4n + 2/4n rule. To quantify aromaticity one can use various aromaticity indices, each of which is a number reflecting some experimentally measured or calculated molecular property, or some feature of the molecular wavefunction, which often has no visual interpretation or may not have direct chemical relevance. We show that computed isotropic magnetic shielding isosurfaces and contour plots provide a feature-rich picture of aromaticity and chemical bonding which is both quantitative and easy-to-visualize and interpret. These isosurfaces and contour plots make good chemical sense as at atomic positions they are pinned to the nuclear shieldings which are experimentally measurable through chemical shifts. As examples we discuss the archetypal aromatic and antiaromatic molecules of benzene and square cyclobutadiene, followed by modern visual interpretations of Clar's aromatic sextet theory, the aromaticity of corannulene and heteroaromaticity.
    Keywords benzene ; isotropy ; magnetism
    Language English
    Dates of publication 2021-0921
    Size p. 9504-9513.
    Publishing place The Royal Society of Chemistry
    Document type Article
    ZDB-ID 1472881-3
    ISSN 1364-548X ; 1359-7345 ; 0009-241X
    ISSN (online) 1364-548X
    ISSN 1359-7345 ; 0009-241X
    DOI 10.1039/d1cc03701c
    Database NAL-Catalogue (AGRICOLA)

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