1
|
Badri Z, Foroutan-Nejad C. On the aromaticity of actinide compounds. Nat Rev Chem 2024; 8:551-560. [PMID: 38907002 DOI: 10.1038/s41570-024-00617-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2024] [Indexed: 06/23/2024]
Abstract
The chemistry of actinides has flourished since the late 2010s with the synthesis of new actinide complexes and clusters. On the theoretical side, a range of tools is available for the characterization of these heavy element-containing compounds, but discrepancies in the assessment of aromaticity using different tools have led to controversies. In this Perspective, we examine the origin of controversies relating to the aromaticity of metallic compounds, with a focus on actinides. The aromaticity of actinides is important, not because these molecules are numerous or have a special role in catalysis or reactivity, but because this topic pushes theories of aromaticity to their limits. Owing to its reference independence, the magnetic criterion of aromaticity has been the most popular choice for the characterization of the aromaticity of metallic compounds, including actinide compounds. Through examination of several case studies, we show why this criterion might be misleading for metallic species and explain how findings relating to actinide compounds could reshape theories of aromaticity, not just for actinides but perhaps also for well-known hydrocarbons.
Collapse
Affiliation(s)
- Zahra Badri
- Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | | |
Collapse
|
2
|
Foroutan-Nejad C. Magnetic Antiaromaticity─Paratropicity─Does Not Necessarily Imply Instability. J Org Chem 2023; 88:14831-14835. [PMID: 37774173 PMCID: PMC10594649 DOI: 10.1021/acs.joc.3c01807] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Indexed: 10/01/2023]
Abstract
Magnetically induced ring currents are a conventional tool for the characterization of aromaticity. Dia- and paratropic currents are thought to be associated with stabilization (aromaticity) and destabilization (antiaromaticity), respectively. In the present work, I have questioned the validity of the paratropic currents as a measure of antiaromaticity among monocyclic hydrocarbons. I have shown that while reduced/oxidized radical ions of hydrocarbons sustain strong paratropic currents, they often gain extra stabilization via cyclic conjugation compared to their acyclic counterparts.
Collapse
Affiliation(s)
- Cina Foroutan-Nejad
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| |
Collapse
|
3
|
Dunlop D, Ludvíková L, Banerjee A, Ottosson H, Slanina T. Excited-State (Anti)Aromaticity Explains Why Azulene Disobeys Kasha's Rule. J Am Chem Soc 2023; 145:21569-21575. [PMID: 37704031 PMCID: PMC10557139 DOI: 10.1021/jacs.3c07625] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Indexed: 09/15/2023]
Abstract
Fluorescence exclusively occurs from the lowest excited state of a given multiplicity according to Kasha's rule. However, this rule is not obeyed by a handful of anti-Kasha fluorophores whose underlying mechanism is still understood merely on a phenomenological basis. This lack of understanding prevents the rational design and property-tuning of anti-Kasha fluorophores. Here, we propose a model explaining the photophysical properties of an archetypal anti-Kasha fluorophore, azulene, based on its ground- and excited-state (anti)aromaticity. We derived our model from a detailed analysis of the electronic structure of the ground singlet, first excited triplet, and quintet states and of the first and second excited singlet states using the perturbational molecular orbital theory and quantum-chemical aromaticity indices. Our model reveals that the anti-Kasha properties of azulene and its derivatives result from (i) the contrasting (anti)aromaticity of its first and second singlet excited states (S1 and S2, respectively) and (ii) an easily accessible antiaromaticity relief pathway of the S1 state. This explanation of the fundamental cause of anti-Kasha behavior may pave the way for new classes of anti-Kasha fluorophores and materials with long-lived, high-energy excited states.
Collapse
Affiliation(s)
- David Dunlop
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí
542/2, Prague 6 160 00, Czech Republic
- Department
of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, Prague 2 128 40, Czech Republic
| | - Lucie Ludvíková
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí
542/2, Prague 6 160 00, Czech Republic
| | - Ambar Banerjee
- Division
of X-ray Photon Science, Department of Physics and Astronomy—Ångström
Laboratory, Uppsala University, Box 523, Uppsala 751 20, Sweden
| | - Henrik Ottosson
- Department
of Chemistry—Ångström Laboratory, Uppsala University, Box 516, Uppsala 751 20, Sweden
| | - Tomáš Slanina
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí
542/2, Prague 6 160 00, Czech Republic
| |
Collapse
|
4
|
Karadakov PB. How Different are the Diamagnetic and Paramagnetic Contributions to Off-Nucleus Shielding in Aromatic and Antiaromatic Rings? Chemphyschem 2023; 24:e202300038. [PMID: 36811600 DOI: 10.1002/cphc.202300038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/15/2023] [Accepted: 02/21/2023] [Indexed: 02/24/2023]
Abstract
The spatial variations in the diamagnetic and paramagnetic contributions to the off-nucleus isotropic shielding, σ i s o r = σ i s o d r + σ i s o p r ${\ {{\sigma }_{{\rm i}{\rm s}{\rm o}}\left({\bf r}\right)=\ \sigma }_{{\rm i}{\rm s}{\rm o}}^{{\rm d}}\left({\bf r}\right)+{\sigma }_{{\rm i}{\rm s}{\rm o}}^{{\rm p}}\left({\bf r}\right)}$ , and to the zz component of the off-nucleus shielding tensor, σ z z r = σ z z d r + σ z z p r ${{{\sigma }_{zz}\left({\bf r}\right)=\sigma }_{zz}^{{\rm d}}\left({\bf r}\right)+{\sigma }_{zz}^{{\rm p}}\left({\bf r}\right)}$ , around benzene (C6 H6 ) and cyclobutadiene (C4 H4 ) are investigated using complete-active-space self-consistent field wavefunctions. Despite the substantial differences between σ i s o r ${{\sigma }_{{\rm i}{\rm s}{\rm o}}\left({\bf r}\right)}$ and σ z z r ${{\sigma }_{zz}\left({\bf r}\right)}$ around the aromatic C6 H6 and the antiaromatic C4 H4 , the diamagnetic and paramagnetic contributions to these quantities, σ i s o d r ${{\sigma }_{{\rm i}{\rm s}{\rm o}}^{{\rm d}}\left({\bf r}\right)}$ and σ z z d r ${{\sigma }_{zz}^{{\rm d}}\left({\bf r}\right)}$ , and σ i s o p r ${{\sigma }_{{\rm i}{\rm s}{\rm o}}^{{\rm p}}\left({\bf r}\right)}$ and σ z z P r ${{\sigma }_{zz}^{{\rm P}}\left({\bf r}\right)}$ , are found to behave similarly in the two molecules, shielding and deshielding, respectively, each ring and its surroundings. The different signs of the most popular aromaticity criterion, the nucleus-independent chemical shift (NICS), in C6 H6 and C4 H4 are shown to follow from a change in the balance between the respective diamagnetic and paramagnetic contributions. Thus, the different NICS values for antiaromatic and antiaromatic molecules cannot be attributed to differences in the ease of access to excited states only; differences in the electron density, which determines the overall bonding picture, also play an important role.
Collapse
Affiliation(s)
- Peter B Karadakov
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| |
Collapse
|
5
|
Abstract
The ascertainment of magnetic aromaticity is not necessarily straightforward, especially for large and bent systems, such as the cycloporphyrin nanorings recently synthesized by the group of Anderson. Six of these cycloporphyrin nanorings were studied here computationally. Indirect methods, based on nuclear shielding and magnetizabilities, and direct methods, based on standard quantum mechanics, were both used effectively to determine their magnetically induced current strength, which mostly confirmed Anderson’s classification. However, in the case of hexanions, and in particular for cyclohexaporphyrin hexacations, a significant cancellation of delocalized diatropic and paratropic flow occurred, showing that the resultant faint aromatic character was a result of competing aromatic and antiaromatic contributions, as also evidenced by the ipsocentric method. A warning is renewed on the use of isotropic shielding to determine the tropicity of the magnetically induced current.
Collapse
|
6
|
Ganguly G, Pathak S, Paul A. Unraveling the stability of cyclobutadiene complexes using aromaticity markers. Phys Chem Chem Phys 2021; 23:16005-16012. [PMID: 34235525 DOI: 10.1039/d1cp01467f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cyclobutadiene (CBD) is the paradigmatic antiaromatic molecule but is known to form highly stable aromatic complexes, e.g. CBD-Fe(CO)3. This intriguing reversal of aromaticity from antiaromatic to aromatic terrain during the complexation process cannot be appropriately handled with single-reference-based theoretical techniques. We explore this aromaticity reversal, for the first time, by a detailed aromaticity analysis using magnetically induced current densities (MICD) and nucleus independent chemical shifts (NICS) using genuine ab initio multi-reference wavefunction-based theory. We trace the dramatic change of aromaticity for a prototypical cyclobutadiene complex, CBD-CH+ (CH+Fe(CO)3), considering a 3D potential energy surface for two independent parameters, namely the approach of CH+ and the automerization cross-section of cyclobutadiene. The 3D potential energy surfaces indicate the presence of a conical intersection/avoided crossing between the ground and the first excited state. The plot of aromaticity indices and the corresponding numerical values show that the change of aromaticity indices is drastic around the conical intersection/avoided crossing and automerization of cyclobutadiene plays a crucial role in the formation of cyclobutadiene complexes. Computations on analogous CBD-Be and CBD-CO systems (Be/COFe(CO)3) emphasize the generality of the conclusions drawn from the CBD-CH+ system.
Collapse
Affiliation(s)
- Gaurab Ganguly
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S C Mullick Road, Kolkata 700032, India.
| | | | | |
Collapse
|
7
|
Plasser F, Glöcklhofer F. Visualisation of Chemical Shielding Tensors (VIST) to Elucidate Aromaticity and Antiaromaticity. European J Org Chem 2021; 2021:2529-2539. [PMID: 34248413 PMCID: PMC8251739 DOI: 10.1002/ejoc.202100352] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/01/2021] [Indexed: 01/25/2023]
Abstract
Aromaticity is a central concept in chemistry, pervading areas from biochemistry to materials science. Recently, chemists also started to exploit intricate phenomena such as the interplay of local and global (anti)aromaticity or aromaticity in non-planar systems and three dimensions. These phenomena pose new challenges in terms of our fundamental understanding and the practical visualisation of aromaticity. To overcome these challenges, a method for the visualisation of chemical shielding tensors (VIST) is developed here that allows for a 3D visualisation with quantitative information about the local variations and anisotropy of the chemical shielding. After exemplifying the method in different planar hydrocarbons, we study two non-planar macrocycles to show the unique benefits of the VIST method for molecules with competing π-conjugated systems and conclude with a norcorrole dimer showing clear evidence of through-space aromaticity. We believe that the VIST method will be a highly valuable addition to the computational toolbox.
Collapse
Affiliation(s)
- Felix Plasser
- Department of ChemistryLoughborough UniversityLoughboroughLE11 3TUUnited Kingdom
| | - Florian Glöcklhofer
- Department of Chemistry andCentre for Processable ElectronicsImperial College LondonMolecular Sciences Research HubLondonW12 0BZUnited Kingdom
| |
Collapse
|
8
|
Exploitation of Baird Aromaticity and Clar’s Rule for Tuning the Triplet Energies of Polycyclic Aromatic Hydrocarbons. CHEMISTRY 2021. [DOI: 10.3390/chemistry3020038] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Polycyclic aromatic hydrocarbons (PAH) are a prominent substance class with a variety of applications in molecular materials science. Their electronic properties crucially depend on the bond topology in ways that are often highly non-intuitive. Here, we study, using density functional theory, the triplet states of four biphenylene-derived PAHs finding dramatically different triplet excitation energies for closely related isomeric structures. These differences are rationalised using a qualitative description of Clar sextets and Baird quartets, quantified in terms of nucleus independent chemical shifts, and represented graphically through a recently developed method for visualising chemical shielding tensors (VIST). The results are further interpreted in terms of a 2D rigid rotor model of aromaticity and through an analysis of the natural transition orbitals involved in the triplet excited states showing good consistency between the different viewpoints. We believe that this work constitutes an important step in consolidating these varying viewpoints of electronically excited states.
Collapse
|
9
|
Abstract
Magnetic shielding studies demonstrate that nickel norcorrole (NiNc) and norcorrole (H2Nc) provide unusual examples of stable molecules with high antagonistic levels of antiaromaticity and aromaticity: Both incorporate an antiaromatic "core", a 14-membered cyclic conjugated subsystem with 16 π electrons, surrounded by an aromatic "halo" in the form of a ring of either 14 atoms and 14 π electrons with a new type of homoconjugation (NiNc), or 18 atoms with 18 π electrons (H2Nc).
Collapse
Affiliation(s)
- Peter B Karadakov
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| |
Collapse
|
10
|
Halder D, Paul A. Understanding the Role of Aromaticity and Conformational Changes in Bond Dissociation Processes of Photo-Protecting Groups. J Phys Chem A 2020; 124:3976-3983. [PMID: 32338513 DOI: 10.1021/acs.jpca.9b11731] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Photoremovable protecting groups (PPGs) provide spatial and temporal control over the release of various chemicals. Using surface hopping studies with multireference electronic structure methods we have unravelled the nuclear and the electronic events at play. Furthermore, the electronic changes along the reaction path were probed using excited state aromaticity quantifiers and orbital analysis. We find that upon irradiation with light of appropriate wavelength on the substituted coumarin system a π-π* electronic excitation occurs which is followed by an electron loss from the aromatic ring on gaining proper alignment between the π* and the C-LG (LG = leaving group) σ*. This alignment is brought about by a critical dihedral angle change in the molecule, which subsequently triggers C-LG bond cleavage. The sequence of events is indicative of an intramolecular electron catalyzed process which is established through investigations of changes in aromaticity of the phenyl ring which acts as an electron reservoir.
Collapse
Affiliation(s)
- Debabrata Halder
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S C Mullick Road, Kolkata 700032, India
| | - Ankan Paul
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S C Mullick Road, Kolkata 700032, India
| |
Collapse
|
11
|
Piccardo M, Soncini A, Fowler PW, Monaco G, Zanasi R. Design of annulene-within-an-annulene systems by the altanisation approach. A study of altan-[n]annulenes. Phys Chem Chem Phys 2020; 22:5476-5486. [DOI: 10.1039/c9cp06835j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Computations on neutral and charged [n]annulenes confirm the general effectiveness of altanisation to design paratropic perimeter circulations. An extension of the design strategy is required for open-shell singlet species.
Collapse
Affiliation(s)
| | | | - Patrick W. Fowler
- Department of Chemistry
- The University of Sheffield
- Sheffield S3 7HF
- UK
| | - Guglielmo Monaco
- Department of Chemistry and Biology
- University of Salerno
- Fisciano 84084
- Italy
| | - Riccardo Zanasi
- Department of Chemistry and Biology
- University of Salerno
- Fisciano 84084
- Italy
| |
Collapse
|
12
|
Conradie J, Brothers PJ, Ghosh A. Main-Group-Element Isophlorin Complexes Revisited: The Question of a Subvalent Central Atom. Inorg Chem 2019; 58:4634-4640. [PMID: 30874434 DOI: 10.1021/acs.inorgchem.9b00201] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A careful density functional theory reexamination of the geometric and electronic structures of reduced main-group porphyrin complexes E(Por)L2 (E = Si or Ge; L = pyridine or tetrahydrofuran), B2(Por), and C2(Por) has confirmed these as pure isophlorin derivatives with normal-valent coordinated central atoms. Only axially unligated Ge(Por) and the dications [B2(Por)]2+ and [C2(Por)]2+ feature aromatic porphyrin ligands. The calculations faithfully reproduce the strong bond-length alternation along the outer rim of the macrocycle in the reduced complexes, consistent with antiaromatic character, as well as much stronger ruffling in the reduced group 14 complexes relative to their nonreduced counterparts such as E(Por)X2 (E = Si or Ge; X = F or Cl). The latter is thought to reflect the lower barrier to nonplanar deformation for the antiaromatic systems. In addition, unlike B2(Por) and its dication, which are planar, C2(Por) and its dication are predicted to be strongly ruffled, reflecting the smaller size of the central C2 unit. The calculations also predict characteristically low ionization potentials and singlet-triplet gaps for the antiaromatic complexes. A brief exploratory study of the as-yet-unknown group 15 complexes E(TPP)(Ph)(py), where E = P and As, also indicated an antiaromatic isophlorin macrocycle coordinated to a pentavalent group 15 center.
Collapse
Affiliation(s)
- Jeanet Conradie
- Department of Chemistry , UiT-The Arctic University of Norway , 9037 Tromsø , Norway.,Department of Chemistry , University of the Free State , 9300 Bloemfontein , Republic of South Africa
| | - Penelope J Brothers
- Department of Chemistry , UiT-The Arctic University of Norway , 9037 Tromsø , Norway.,School of Chemical Sciences , The University of Auckland , Private Bag, 92019 Auckland , New Zealand
| | - Abhik Ghosh
- Department of Chemistry , UiT-The Arctic University of Norway , 9037 Tromsø , Norway
| |
Collapse
|
13
|
Janda T, Foroutan‐Nejad C. Why is Benzene Unique? Screening Magnetic Properties of C6H6Isomers. Chemphyschem 2018; 19:2357-2363. [DOI: 10.1002/cphc.201800364] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Tomáš Janda
- Department of Chemistry, Faculty of ScienceMasaryk University Kamenice 5, CZ – 62500 Brno Czech Republic
- Institute of Chemistry and Technology of Macromolecular Materials, Faculty of Chemical TechnologyUniversity of Pardubice
| | - Cina Foroutan‐Nejad
- CEITEC – Central European Institute of Technology, Masaryk University Kamenice 5, CZ – 62500 Brno Czech Republic
| |
Collapse
|
14
|
Firouzi R, Shafie H, Tohidnia H. Characterization of Local Aromaticity in Polycyclic Conjugated Hydrocarbons Based on Anisotropy of π-Electron Density. ChemistrySelect 2017. [DOI: 10.1002/slct.201702407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Rohoullah Firouzi
- Department of Physical Chemistry; Chemistry and Chemical Engineering Research Center of Iran; P.O. Box 14968-13151 Tehran Iran
| | - Hoda Shafie
- Department of Physical Chemistry; Chemistry and Chemical Engineering Research Center of Iran; P.O. Box 14968-13151 Tehran Iran
| | - Hassan Tohidnia
- Department of Physical Chemistry; Chemistry and Chemical Engineering Research Center of Iran; P.O. Box 14968-13151 Tehran Iran
| |
Collapse
|
15
|
Kumar C, Fliegl H, Sundholm D. Relation Between Ring Currents and Hydrogenation Enthalpies for Assessing the Degree of Aromaticity. J Phys Chem A 2017; 121:7282-7289. [DOI: 10.1021/acs.jpca.7b07607] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Chandan Kumar
- Hylleraas
Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, P.
O. Box 1033, N-1315 Blindern, Norway
| | - Heike Fliegl
- Hylleraas
Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, P.
O. Box 1033, N-1315 Blindern, Norway
| | - Dage Sundholm
- Department
of Chemistry, University of Helsinki, P.O. Box 55, A. I. Virtanens Plats
1, FIN-00014 Helsinki, Finland
| |
Collapse
|
16
|
Sundholm D, Fliegl H, Berger RJ. Calculations of magnetically induced current densities: theory and applications. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2016. [DOI: 10.1002/wcms.1270] [Citation(s) in RCA: 163] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Dage Sundholm
- Department of Chemistry; University of Helsinki; Helsinki Finland
| | - Heike Fliegl
- Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry; University of Oslo; Oslo Norway
| | - Raphael J.F. Berger
- Paris-Lodron University of Salzburg; Chemistry of Materials; Salzburg Austria
| |
Collapse
|
17
|
Banerjee A, Halder D, Ganguly G, Paul A. Deciphering the cryptic role of a catalytic electron in a photochemical bond dissociation using excited state aromaticity markers. Phys Chem Chem Phys 2016; 18:25308-25314. [DOI: 10.1039/c6cp03789e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Upon photoexcitation of 5-phenyltetrazole, an electron is injected from the phenyl ring to the tetrazole ring, which performs a catalytic role in the photolytic dissociation of N2. The footprints of the “mercenary” electron are captured via dramatic changes in excited state aromaticity of the associated rings.
Collapse
Affiliation(s)
- Ambar Banerjee
- Raman Centre for Atomic Molecular and Optical Sciences Indian Association for the Cultivation of Science 2A & 2B
- India
| | - Debabrata Halder
- Raman Centre for Atomic Molecular and Optical Sciences Indian Association for the Cultivation of Science 2A & 2B
- India
| | - Gaurab Ganguly
- Raman Centre for Atomic Molecular and Optical Sciences Indian Association for the Cultivation of Science 2A & 2B
- India
| | - Ankan Paul
- Raman Centre for Atomic Molecular and Optical Sciences Indian Association for the Cultivation of Science 2A & 2B
- India
| |
Collapse
|
18
|
Sundholm D, Berger RJF, Fliegl H. Analysis of the magnetically induced current density of molecules consisting of annelated aromatic and antiaromatic hydrocarbon rings. Phys Chem Chem Phys 2016; 18:15934-42. [DOI: 10.1039/c6cp01968d] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The aromatic pathway of molecules with annelated aromatic and antiaromatic rings has been studied by calculating magnetically induced current densities.
Collapse
Affiliation(s)
- Dage Sundholm
- University of Helsinki
- Department of Chemistry
- Finland
| | | | - Heike Fliegl
- Centre for Theoretical and Computational Chemistry (CTCC)
- Department of Chemistry
- University of Oslo
- NO-0315 Oslo
- Norway
| |
Collapse
|
19
|
Banerjee A, Ganguly G, Roy L, Pathak S, Paul A. A Serendipitous Rendezvous with a Four-Center Two-Electron Bonded Intermediate in the Aerial Oxidation of Hydrazine. Chemistry 2015; 22:1216-22. [PMID: 26552004 DOI: 10.1002/chem.201503455] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Indexed: 11/10/2022]
Abstract
Oxidation by dioxygen has a rich repertoire of mechanistic intricacies. Herein, we report a hitherto unknown paradigm of dioxygen activation reaction which propagates through a four center two electron (4c-2e) bound species. Using static DFT and ab initio quantum chemical techniques we have unraveled the oxidation pathway for hydrazine and its methylated analogues by dioxygen which involves formation of this unconventional 4c-2e bonded species en route to the oxidation products. Inconvertible evidence in favor of such an unprecedented dioxygen activation route is provided by capturing the events of formation of the 4c-2e species in aqueous phase for hydrazine and its congeners and the experimentally observed products from the respective 4c-2e species, like H2O2 and N2H2 , diazene in the case of hydrazine using Car-Parrinello molecular dynamics simulations.
Collapse
Affiliation(s)
- Ambar Banerjee
- Raman Centre for Atomic Molecular and Optical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S.C. Mullick Road, Kolkata, 700032, India
| | - Gaurab Ganguly
- Raman Centre for Atomic Molecular and Optical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S.C. Mullick Road, Kolkata, 700032, India
| | - Lisa Roy
- Raman Centre for Atomic Molecular and Optical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S.C. Mullick Road, Kolkata, 700032, India
| | - Shubhrodeep Pathak
- Department of Molecular Theory and Spectroscopy, Max-Planck Institute for Chemical Energy Conversion, Room: 503, Stiftstraße 34-36, 45470, Mülheim an der Ruhr, Germany
| | - Ankan Paul
- Raman Centre for Atomic Molecular and Optical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S.C. Mullick Road, Kolkata, 700032, India.
| |
Collapse
|
20
|
Du D, Sundholm D, Fliegl H. Evaluating Shielding‐Based Ring‐Current Models by Using the Gauge‐Including Magnetically Induced Current Method. J CHIN CHEM SOC-TAIP 2015. [DOI: 10.1002/jccs.201500027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Dou Du
- University of Helsinki, Department of Chemistry, P.O. Box 55 (A.I. Virtanens plats 1), FIN‐00014 University of Helsinki, Finland
| | - Dage Sundholm
- University of Helsinki, Department of Chemistry, P.O. Box 55 (A.I. Virtanens plats 1), FIN‐00014 University of Helsinki, Finland
| | - Heike Fliegl
- Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, 0315 Oslo, Norway
| |
Collapse
|
21
|
Torres-Vega JJ, Vásquez-Espinal A, Ruiz L, Fernández-Herrera MA, Alvarez-Thon L, Merino G, Tiznado W. Revisiting Aromaticity and Chemical Bonding of Fluorinated Benzene Derivatives. ChemistryOpen 2015; 4:302-7. [PMID: 26246992 PMCID: PMC4522180 DOI: 10.1002/open.201402110] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Indexed: 11/07/2022] Open
Abstract
The electron delocalization of benzene (C6H6) and hexafluorobenzene (C6F6) was analyzed in terms of the induced magnetic field, nucleus-independent chemical shift (NICS), and ring current strength (RCS). The computed out-of-plane component of the induced magnetic field at a distance (r) greater than or equal to 1.0 Å above the ring center correlates well (R (2)>0.99) with the RCS value. According to these criteria, fluorination has two effects on the C6 skeleton; concomitantly, the resonant effects diminish the π electron delocalization and the inductive effects decrease the charge density at the ring center and therefore reduce the magnitude of the paratropic current generated in this region. The equilibrium between both effects decreases aromaticity in the fluorinated benzene derivatives. These results can be extrapolated to determine the aromaticity of any derivative within the series of fluorinated benzene derivatives (C6H(6-n)F n , where n=1-5).
Collapse
Affiliation(s)
- Juan J Torres-Vega
- Doctorado en Fisicoquímica Molecular, Facultad de Ciencias Exactas, Universidad Andres Bello República 275, Santiago, Chile
| | - Alejandro Vásquez-Espinal
- Doctorado en Fisicoquímica Molecular, Facultad de Ciencias Exactas, Universidad Andres Bello República 275, Santiago, Chile
| | - Lina Ruiz
- Centro de Investigación Biomédica, Universidad Autónoma de Chile Llano Subercaseaux 2801, Santiago, Chile
| | - María A Fernández-Herrera
- Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados, Unidad Mérida Km 6 Antigua Carretera a Progreso. Apdo. Postal 73, Cordemex, CP., 97310, Mérida, Yuc., Mexico
| | - Luis Alvarez-Thon
- Departamento de Ciencias Físicas, Facultad de Ciencias Exactas, Universidad Andres Bello República 220, Santiago, Chile
| | - Gabriel Merino
- Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados, Unidad Mérida Km 6 Antigua Carretera a Progreso. Apdo. Postal 73, Cordemex, CP., 97310, Mérida, Yuc., Mexico
| | - William Tiznado
- Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andres Bello República 275, Santiago, Chile
| |
Collapse
|
22
|
Abstract
Ab initio calculations confirm that the design of large paratropic circuits through altanisation fails in altan-[10,5]coronene. This molecule is predicted to be an open-shell singlet biradical, like the cycloacene that it contains.
Collapse
Affiliation(s)
- Guglielmo Monaco
- Dip. di Chimica e Biologia “Adolfo Zambelli”
- Università di Salerno
- Fisciano
- Italy
| |
Collapse
|
23
|
Berger RJF, Repisky M, Komorovsky S. How does relativity affect magnetically induced currents? Chem Commun (Camb) 2015; 51:13961-3. [DOI: 10.1039/c5cc05732a] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Relativity contributes via induced spin-density to magnetically induced currents (jB) in closed-shell systems and in general enhances curvature in jB.
Collapse
Affiliation(s)
- R. J. F. Berger
- Chemistry of Materials
- Paris-Lodron-University Salzburg
- A-5020 Salzburg
- Austria
| | - M. Repisky
- Department of Chemistry University of Tromsø
- N-9037 Tromsø
- Norway
| | - S. Komorovsky
- Department of Chemistry University of Tromsø
- N-9037 Tromsø
- Norway
| |
Collapse
|
24
|
Xia Y, Yao H, Cui M, Ma Y, Kong Z, Wu B, Qi Z, Sun Y. Theoretical and experimental investigations on mono-substituted and multi-substituted functional polyhedral oligomeric silsesquioxanes. RSC Adv 2015. [DOI: 10.1039/c5ra14298a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Theoretical and experimental investigations on substituted functional polyhedral oligomeric silsesquioxanes.
Collapse
Affiliation(s)
- Yong Xia
- College of Chemistry and Chemical Engineering
- Southeast University
- Nanjing
- PR China
| | - Hongtao Yao
- College of Chemistry and Chemical Engineering
- Southeast University
- Nanjing
- PR China
| | - Meifang Cui
- College of Chemistry and Chemical Engineering
- Southeast University
- Nanjing
- PR China
| | - Yun Ma
- College of Chemistry and Chemical Engineering
- Southeast University
- Nanjing
- PR China
| | - Zhineng Kong
- College of Chemistry and Chemical Engineering
- Southeast University
- Nanjing
- PR China
| | - Baoying Wu
- College of Chemistry and Chemical Engineering
- Southeast University
- Nanjing
- PR China
| | - Zhengjian Qi
- College of Chemistry and Chemical Engineering
- Southeast University
- Nanjing
- PR China
| | - Yueming Sun
- College of Chemistry and Chemical Engineering
- Southeast University
- Nanjing
- PR China
| |
Collapse
|
25
|
Torres-Vega JJ, Vásquez-Espinal A, Caballero J, Valenzuela ML, Alvarez-Thon L, Osorio E, Tiznado W. Minimizing the Risk of Reporting False Aromaticity and Antiaromaticity in Inorganic Heterocycles Following Magnetic Criteria. Inorg Chem 2014; 53:3579-85. [DOI: 10.1021/ic4030684] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Juan J. Torres-Vega
- Departamento
de Ciencias Químicas, Facultad de Ciencias Exactas Universidad Andres Bello, República 275, Santiago, Chile
| | - Alejandro Vásquez-Espinal
- Departamento
de Ciencias Químicas, Facultad de Ciencias Exactas Universidad Andres Bello, República 275, Santiago, Chile
| | - Julio Caballero
- Centro
de Bioinformática y Simulación Molecular, Universidad de Talca, 2 Norte 685, Casilla 721, Talca, Chile
| | - María L. Valenzuela
- Departamento
de Ciencias Químicas, Facultad de Ciencias Exactas Universidad Andres Bello, República 275, Santiago, Chile
| | - Luis Alvarez-Thon
- Departamento
de Ciencias Físicas, Facultad de Ciencias Exactas, Universidad Andres Bello, República 220, Santiago, Chile
| | - Edison Osorio
- Centro
de Bioinformática y Simulación Molecular, Universidad de Talca, 2 Norte 685, Casilla 721, Talca, Chile
| | - William Tiznado
- Departamento
de Ciencias Químicas, Facultad de Ciencias Exactas Universidad Andres Bello, República 275, Santiago, Chile
| |
Collapse
|
26
|
Firouzi R. The degeneracy of the Hessian eigenvalues of the π-electron density: A new manifestation of aromaticity. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.01.051] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
27
|
Badri Z, Pathak S, Fliegl H, Rashidi-Ranjbar P, Bast R, Marek R, Foroutan-Nejad C, Ruud K. All-Metal Aromaticity: Revisiting the Ring Current Model among Transition Metal Clusters. J Chem Theory Comput 2013; 9:4789-96. [DOI: 10.1021/ct4007184] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zahra Badri
- CEITEC − Central European Institute of Technology, Masaryk University, Kamenice 5/A4, CZ−62500 Brno, Czech Republic
- School
of Chemistry, College of Science, University of Tehran, Tehran, Iran
| | - Shubhrodeep Pathak
- Raman Center for Atomic, Molecular and Optical Sciences, Indian Association for the Cultivation of Science, Kolkata 700 032, India
| | - Heike Fliegl
- Centre for Theoretical and Computational
Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, N−0315 Oslo, Norway
| | | | - Radovan Bast
- Laboratoire de Chimie et Physique Quantiques (UMR 5626), CNRS/Université de Toulouse 3 (Paul Sabatier), 118 route de Narbonne, F−31062 Toulouse, France
- Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, AlbaNova University Center, S-10691 Stockholm, Sweden
| | - Radek Marek
- CEITEC − Central European Institute of Technology, Masaryk University, Kamenice 5/A4, CZ−62500 Brno, Czech Republic
- National Center
for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5/A4, CZ−62500 Brno, Czech Republic
| | - Cina Foroutan-Nejad
- National Center
for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5/A4, CZ−62500 Brno, Czech Republic
| | - Kenneth Ruud
- Centre
for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø—The Arctic University of Norway, N-9037 Tromsø, Norway
| |
Collapse
|
28
|
Valiev RR, Fliegl H, Sundholm D. Insights into Magnetically Induced Current Pathways and Optical Properties of Isophlorins. J Phys Chem A 2013; 117:9062-8. [DOI: 10.1021/jp404828n] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Rashid R. Valiev
- National Research Tomsk Polytechnic University, 43a Lenin
Avenue, Building 2, Tomsk 634050, Russian Federation
- Tomsk State University, Lenina Avenue 36, Tomsk 634050, Russian Federation
| | - Heike Fliegl
- Centre for
Theoretical
and Computational Chemistry (CTCC), Department of Chemistry, University of Oslo, P.O.
Box 1033 Blindern, 0315 Oslo, Norway
| | - Dage Sundholm
- Department
of Chemistry, University of Helsinki, P.O. Box 55 (A. I. Virtanens plats 1), FIN-00014 University of Helsinki, Finland
| |
Collapse
|