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Leyva-Parra L, Pino-Rios R, Inostroza D, Solà M, Alonso M, Tiznado W. Aromaticity and Magnetic Behavior in Benzenoids: Unraveling Ring Current Combinations. Chemistry 2024; 30:e202302415. [PMID: 37955853 DOI: 10.1002/chem.202302415] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Indexed: 11/14/2023]
Abstract
Nowadays, an active research topic is the connection between Clar's rule, aromaticity, and magnetic properties of polycyclic benzenoid hydrocarbons. In the present work, we employ a meticulous magnetically induced current density analysis to define the net current flowing through any cyclic circuit, connecting it to aromaticity based on the ring current concept. Our investigation reveals that the analyzed polycyclic systems display a prominent global ring current, contrasting with subdued semi-local and local ring currents. These patterns align with Clar's aromatic π-sextets only in cases where migrating π-sextet structures are invoked. The results of this study will enrich our comprehension of aromaticity and magnetic behavior in such systems, offering significant insights into coexisting ring current circuits in these systems.
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Affiliation(s)
- Luis Leyva-Parra
- Centro de Química Teórica & Computacional (CQT&C), Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andrés Bello, Av. República 275, 8370146, Santiago, Chile
- Programa de Doctorado en Fisicoquímica Molecular, Facultad de Ciencias Exactas, Universidad Andrés Bello, Av. República 275, 8370146, Santiago, Chile
| | - Ricardo Pino-Rios
- Instituto de Estudios de la Salud, Universidad Arturo Prat, Iquique, 1100000, Chile
- Química y Farmacia, Facultad de Ciencias de la Salud, Universidad Arturo Prat, Casilla 121, Iquique, 1100000, Chile
| | - Diego Inostroza
- Centro de Química Teórica & Computacional (CQT&C), Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andrés Bello, Av. República 275, 8370146, Santiago, Chile
- Programa de Doctorado en Fisicoquímica Molecular, Facultad de Ciencias Exactas, Universidad Andrés Bello, Av. República 275, 8370146, Santiago, Chile
| | - Miquel Solà
- Institute of Computational Chemistry and Catalysis, Departament of Chemistry, University of Girona, C/M Aurèlia Campmany 69, 17003, Girona, Catalonia, Spain
| | - Mercedes Alonso
- Departament of General Chemistry (ALGC), Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
| | - William Tiznado
- Centro de Química Teórica & Computacional (CQT&C), Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andrés Bello, Av. República 275, 8370146, Santiago, Chile
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2
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Tuersun M, Kerim A. A study on the aromaticity and magnetic properties of N-confused porphyrins. ROYAL SOCIETY OPEN SCIENCE 2020; 7:200069. [PMID: 32874619 PMCID: PMC7428255 DOI: 10.1098/rsos.200069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 06/04/2020] [Indexed: 06/11/2023]
Abstract
In this paper, topological resonance energy (TRE) methods were used to describe the global aromaticity of nitrogen confused porphyrin (NCP) isomers. The TRE results show that all NCP isomers exhibit lower aromaticity than the normal porphyrins, and their aromaticity decreases as the number of confused pyrrole rings in the molecule increases. In the NCPs, global aromaticity decreases as the distance between the nitrogen atoms increases. The bond resonance energy (BRE) and circuit resonance energy (CRE) indices were applied to study local aromaticity and conjugated pathways. Both the BRE and CRE indices revealed that individual pyrrolic subunits maintain their strong aromatic character and are the main source of global aromaticity. Ring currents (RC) were analysed using the Hückel-London model. RC results revealed that the macrocyclic electron conjugation pathway is the main source of diatropicity. As the number of confused pyrrole rings in the molecule increases, its diatropicity gradually decreases. In the confused pyrrole rings of the NCP isomers, the diatropic RC passing through the β-positions is always weaker than that passing through the inner sections. This is unrelated to the location of the protonated or non-protonated nitrogen atom at the periphery of the molecule and must be ascribed to the unique properties of the confused pyrrole rings.
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3
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Shao P, Ding LP, Luo DB, Lu C. Probing the structural, bonding, electronic and magnetic properties of transition–metal borazine systems: Com(borazine)n (m = 1, 2; n = 1–3). Mol Phys 2019. [DOI: 10.1080/00268976.2019.1667542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Peng Shao
- Department of Physics, Shaanxi University of Science & Technology, Xi’an, People’s Republic of China
| | - Li Ping Ding
- Department of Physics, Shaanxi University of Science & Technology, Xi’an, People’s Republic of China
| | - Dao-Bin Luo
- Department of Physics, Shaanxi University of Science & Technology, Xi’an, People’s Republic of China
| | - Cheng Lu
- Department of Physics, Nanyang Normal University, Nanyang, People’s Republic of China
- Department of Physics and High Pressure Science and Engineering Center, University of Nevada, Las Vegas, NV, USA
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4
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Feng LY, Li R, Zhai HJ. Boron-based inorganic heterocyclic clusters: electronic structure, chemical bonding, aromaticity, and analogy to hydrocarbons. Phys Chem Chem Phys 2019; 21:20523-20537. [PMID: 31304948 DOI: 10.1039/c9cp03254a] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This Perspective article deals with recent computational and experimental findings in boron-based heterocyclic clusters, which focuses on binary B-O and B-S clusters, as well as relevant ternary B-X-H (X = O, S, N) species. Boron is electron-deficient and boron clusters do not form monocyclic rings or linear chains. Boron-based heterocyclic clusters are intuitively even more electron-deficient and feature exotic chemical bonding, which make use of O 2p, S 3p, or N 2p lone-pairs for π delocalization over heterocyclic rings, facilitating new cluster structures and new types of bonding. Rhombic, pentagonal, hexagonal, and polycyclic clusters are discussed herein. Rhombic species are stabilized by four-center four-electron (4c-4e) π bonding, that is, the o-bond. An o-bond cluster differs from a typical 4π antiaromatic system, because it has 4π electrons in an unusual bonding/nonbonding combination, which takes advantage of the empty 2pz atomic orbitals from electron-deficient boron centers. A variety of examples (notably including boronyl boroxine) possess a hexagonal ring, as well as magic 6π electron-counting, making them new members of the inorganic benzene family. Pentagonal clusters bridge rhombic o-bond systems and inorganic benzenes, but they do not necessarily favor 6π electron-counting as in cyclopentadienide anion. In contrast, pentagonal 4π clusters are stable, leading to the concept of pentagonal o-bond. One electron can overturn the potential energy landscape of a system, enabling rhombic-to-hexagonal structural transition, which further reinforces the idea that 4π electron-counting is favorable for rhombic systems and 6π is magic for hexagonal rings. The bonding analogy between heterocyclic clusters and hydrocarbons goes beyond monocyclic species, which allows rational design of boron-based inorganic analogs of polycyclic aromatic hydrocarbons, including s-indacene as a puzzling aromatic/antiaromatic system. Selected linear B-O clusters are also briefly discussed, featuring dual 3c-4e π bonds, that is, ω-hyperbonds. Dual ω-hyperbonds, rhombic or pentagonal o-bond, and inorganic benzenes share a common chemical origin. The field of boron-based heterocyclic clusters is still in its infant stage, and much new chemistry remains to be discovered in forthcoming experimental and theoretical studies.
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Affiliation(s)
- Lin-Yan Feng
- Nanocluster Laboratory, Institute of Molecular Science, Shanxi University, Taiyuan 030006, China.
| | - Rui Li
- Nanocluster Laboratory, Institute of Molecular Science, Shanxi University, Taiyuan 030006, China.
| | - Hua-Jin Zhai
- Nanocluster Laboratory, Institute of Molecular Science, Shanxi University, Taiyuan 030006, China.
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5
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Trinquier G, Malrieu JP. Predicting the Open-Shell Character of Polycyclic Hydrocarbons in Terms of Clar Sextets. J Phys Chem A 2018; 122:1088-1103. [DOI: 10.1021/acs.jpca.7b11095] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Georges Trinquier
- Laboratoire de Chimie et Physique Quantiques,
IRSAMC−CNRS-UMR5626, Université Paul-Sabatier (Toulouse III), 31062 Toulouse Cedex 4, France
| | - Jean-Paul Malrieu
- Laboratoire de Chimie et Physique Quantiques,
IRSAMC−CNRS-UMR5626, Université Paul-Sabatier (Toulouse III), 31062 Toulouse Cedex 4, France
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6
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Baranac-Stojanović M. 4π-Electron B-N Monocycles: Stability and (Anti)aromaticity. European J Org Chem 2017. [DOI: 10.1002/ejoc.201700959] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Marija Baranac-Stojanović
- Faculty of Chemistry; University of Belgrade; Studentski trg 12-16, P. O. Box 158 11000 Belgrade Serbia
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7
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Li DZ, Feng LY, Pei L, Zhang LJ, Wu SG, Zhai HJ. Pentagonal five-center four-electron π bond in ternary B3N2H5 cluster: an extension of the concept of three-center four-electron ω bond. Phys Chem Chem Phys 2017; 19:2479-2486. [DOI: 10.1039/c6cp07954g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ternary B3N2H5 (C2v, 1A1) cluster has a heteroatomic B3N2 ring, with 4π electrons in a robust bonding/nonbonding combination, which is proposed as a five-center four-electron o-bond.
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Affiliation(s)
- Da-Zhi Li
- Binzhou Key Laboratory of Materials Chemistry
- Department of Chemical Engineering
- Binzhou University
- Binzhou 256603
- P. R. China
| | - Lin-Yan Feng
- Nanocluster Laboratory
- Institute of Molecular Science
- Shanxi University
- Taiyuan 030006
- P. R. China
| | - Ling Pei
- Binzhou Key Laboratory of Materials Chemistry
- Department of Chemical Engineering
- Binzhou University
- Binzhou 256603
- P. R. China
| | - Li-Juan Zhang
- Binzhou Key Laboratory of Materials Chemistry
- Department of Chemical Engineering
- Binzhou University
- Binzhou 256603
- P. R. China
| | - Shu-Guo Wu
- Binzhou Key Laboratory of Materials Chemistry
- Department of Chemical Engineering
- Binzhou University
- Binzhou 256603
- P. R. China
| | - Hua-Jin Zhai
- Nanocluster Laboratory
- Institute of Molecular Science
- Shanxi University
- Taiyuan 030006
- P. R. China
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8
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Gao L, Zeng Y, Zhang X, Meng L. Comparative studies on group III σ-hole and π-hole interactions. J Comput Chem 2016; 37:1321-7. [PMID: 26949204 DOI: 10.1002/jcc.24347] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 01/02/2016] [Accepted: 02/07/2016] [Indexed: 12/24/2022]
Abstract
The σ-hole of M2 H6 (M = Al, Ga, In) and π-hole of MH3 (M = Al, Ga, In) were discovered and analyzed, the bimolecular complexes M2 H6 ···NH3 and MH3 ···N2 P2 F4 (M = Al, Ga, In) were constructed to carry out comparative studies on the group III σ-hole interactions and π-hole interactions. The two types of interactions are all partial-covalent interactions; the π-hole interactions are stronger than σ-hole interactions. The electrostatic energy is the largest contribution for forming the σ-hole and π-hole interaction, the polarization energy is also an important factor to form the M···N interaction. The electrostatic energy contributions to the interaction energy of the σ-hole interactions are somewhat greater than those of the π-hole interactions. However, the polarization contributions for the π-hole interactions are somewhat greater than those for the σ-hole interactions.
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Affiliation(s)
- Lei Gao
- Institute of Computational Quantum Chemistry, College of Chemistry and Material Science, Hebei Normal University, Shijiazhuang, 050024, People's Republic of China
| | - Yanli Zeng
- Institute of Computational Quantum Chemistry, College of Chemistry and Material Science, Hebei Normal University, Shijiazhuang, 050024, People's Republic of China
| | - Xueying Zhang
- Institute of Computational Quantum Chemistry, College of Chemistry and Material Science, Hebei Normal University, Shijiazhuang, 050024, People's Republic of China
| | - Lingpeng Meng
- Institute of Computational Quantum Chemistry, College of Chemistry and Material Science, Hebei Normal University, Shijiazhuang, 050024, People's Republic of China
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9
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Li D, Zhang S, Dong C. Binary B
4
S
4
Rhombic Clusters as Promising Inorganic Ligands for Triple‐Decker Sandwich Complexes. Eur J Inorg Chem 2016. [DOI: 10.1002/ejic.201501439] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Da‐Zhi Li
- Binzhou Key Laboratory of Material Chemistry, Department of Chemistry and Chemical Engineering, Binzhou University, Binzhou 256603, People's Republic of China, http://hgx.bzu.edu.cn/
| | - Shi‐Guo Zhang
- Binzhou Key Laboratory of Material Chemistry, Department of Chemistry and Chemical Engineering, Binzhou University, Binzhou 256603, People's Republic of China, http://hgx.bzu.edu.cn/
| | - Chen‐Chu Dong
- Binzhou Key Laboratory of Material Chemistry, Department of Chemistry and Chemical Engineering, Binzhou University, Binzhou 256603, People's Republic of China, http://hgx.bzu.edu.cn/
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10
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Wu W, Li X, Meng L, Zheng S, Zeng Y. Understanding the Properties of Inorganic Benzenes Based on π-Electron Densities. J Phys Chem A 2015; 119:2091-7. [DOI: 10.1021/jp511862u] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Wenjie Wu
- College
of Chemistry and Material Science, Hebei Normal University, Shijiazhuang 050024, P. R. China
- Beijing
Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials,
School of Chemistry, Beijing Institute of Technology, Beijing 100081, China
| | - Xiaoyan Li
- College
of Chemistry and Material Science, Hebei Normal University, Shijiazhuang 050024, P. R. China
| | - Lingpeng Meng
- College
of Chemistry and Material Science, Hebei Normal University, Shijiazhuang 050024, P. R. China
| | - Shijun Zheng
- College
of Chemistry and Material Science, Hebei Normal University, Shijiazhuang 050024, P. R. China
| | - Yanli Zeng
- College
of Chemistry and Material Science, Hebei Normal University, Shijiazhuang 050024, P. R. China
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11
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Li DZ, Zhang LJ, Ou T, Zhang HX, Pei L, Zhai HJ, Li SD. Ternary B2X2H2(X = O and S) rhombic clusters and their potential use as inorganic ligands in sandwich-type (B2X2H2)2Ni complexes. Phys Chem Chem Phys 2015; 17:16798-804. [DOI: 10.1039/c5cp02394g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Boron-based ternary B2O2H2and B2S2H2clusters possess a rhombic, heteroatomic ring with 4π electrons in a nonbonding/bonding combination, differing from cyclobutadiene.
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Affiliation(s)
- Da-Zhi Li
- Binzhou Key Laboratory of Materials Chemistry
- Department of Chemical Engineering
- Binzhou University
- Binzhou 256603
- P. R. China
| | - Li-Juan Zhang
- Binzhou Key Laboratory of Materials Chemistry
- Department of Chemical Engineering
- Binzhou University
- Binzhou 256603
- P. R. China
| | - Ting Ou
- Nanocluster Laboratory
- Institute of Molecular Science
- Shanxi University
- Taiyuan 030006
- P. R. China
| | - Hai-Xia Zhang
- Binzhou Key Laboratory of Materials Chemistry
- Department of Chemical Engineering
- Binzhou University
- Binzhou 256603
- P. R. China
| | - Ling Pei
- Binzhou Key Laboratory of Materials Chemistry
- Department of Chemical Engineering
- Binzhou University
- Binzhou 256603
- P. R. China
| | - Hua-Jin Zhai
- Nanocluster Laboratory
- Institute of Molecular Science
- Shanxi University
- Taiyuan 030006
- P. R. China
| | - Si-Dian Li
- Nanocluster Laboratory
- Institute of Molecular Science
- Shanxi University
- Taiyuan 030006
- P. R. China
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12
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Krygowski TM, Szatylowicz H, Stasyuk OA, Dominikowska J, Palusiak M. Aromaticity from the viewpoint of molecular geometry: application to planar systems. Chem Rev 2014; 114:6383-422. [PMID: 24779633 DOI: 10.1021/cr400252h] [Citation(s) in RCA: 365] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Tadeusz M Krygowski
- Department of Chemistry, Warsaw University , Pasteura 1, 02-093 Warsaw, Poland
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13
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Jacobsen H. Bond descriptors based on kinetic energy densities reveal regions of slow electrons – Another look at aromaticity. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.07.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Samanta PK, Manna AK, Pati SK. Thieno analogues of RNA nucleosides: a detailed theoretical study. J Phys Chem B 2012; 116:7618-26. [PMID: 22671305 DOI: 10.1021/jp301752k] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We use first-principles density functional theory calculations to investigate the structural, energetic, bonding aspects, and optical properties of recently synthesized thieno-analogues of RNA nucleosides. The results are compared against the findings obtained for both the natural nucleosides as well as available experimental data. We find that the modified nucleosides form the hydrogen bonded Watson-Crick (WC) base pairing with similar H-bonding energy as obtained for the natural nucleosides. We have calculated and compared the charge transfer integrals for the H-bonded natural and thieno-modified nucleosides. We find that the thieno modification of these nucleosides strongly affects the charge transfer integrals due to the difference in extent of orbital delocalization in these two types of nucleosides. We also find that the degree of reduction of charge transfer integrals is larger for the H-bonded A-U pair than in the G-C pair. We also focus on the optical absorption properties of these thieno-modified nucleosides and their WC H-bonded base pairs in gas phase as well as with implicit water. Our calculated results show that the low energy peaks in the absorption spectra mainly arise because of the π-π* electronic transition for both the nucleosides, and the observed red shift for thieno-nucleosides compared to natural nucleosides are consistent with the calculated decrease in electronic gaps. Our results demonstrate that the thieno modification of natural nucleosides significantly modifies their electronic and optical properties, although the basic structural and bonding aspects remained the same. It also gives a microscopic understanding of the experimentally observed optical behaviors.
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Affiliation(s)
- Pralok K Samanta
- Theoretical Sciences Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Jakkur P.O., Bangalore 560064, India
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15
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Abstract
Aromaticity is indispensable for explaining a variety of chemical behaviors, including reactivity, structural features, relative energetic stabilities, and spectroscopic properties. When interpreted as the spatial delocalization of π-electrons, it represents the driving force for the stabilization of many planar molecular structures. A delocalized electron system is sensitive to an external magnetic field; it responds with an induced magnetic field having a particularly long range. The shape of the induced magnetic field reflects the size and strength of the system of delocalized electrons and can have a large influence on neighboring molecules. In 2004, we proposed using the induced magnetic field as a means of estimating the degree of electron delocalization and aromaticity in planar as well as in nonplanar molecules. We have since tested the method on aromatic, antiaromatic, and nonaromatic compounds, and a refinement now allows the individual treatment of core-, σ-, and π-electrons. In this Account, we describe the use of the induced magnetic field as an analytical probe for electron delocalization and its application to a large series of uncommon molecules. The compounds include borazine; all-metal aromatic systems Al(4)(n-); molecular stars Si(5)Li(n)(6-n); electronically stabilized planar tetracoordinate carbon; planar hypercoordinate atoms inside boron wheels; and planar boron wheels with fluxional internal boron cluster moieties. In all cases, we have observed that planar structures show a high degree of electron delocalization in the π-electrons and, in some examples, also in the σ-framework. Quantitatively, the induced magnetic field has contributions from the entire electronic system of a molecule, but at long range the contributions arising from the delocalized electronic π-system dominate. The induced magnetic field can only indirectly be confirmed by experiment, for example, through intermolecular contributions to NMR chemical shifts. We show that calculating the induced field is a useful method for understanding any planar organic or inorganic system, as it corresponds to the intuitive Pople model for explaining the anomalous proton chemical shifts in aromatic molecules. Indeed, aromatic, antiaromatic, and nonaromatic molecules show differing responses to an external field; that is, they reduce, augment, or do not affect the external field at long range. The induced field can be dissected into different orbital contributions, in the same way that the nucleus-independent chemical shift or the shielding function can be separated into component contributions. The result is a versatile tool that is particularly useful in the analysis of planar, densely packed systems with strong orbital contributions directly atop individual atoms.
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Affiliation(s)
- Rafael Islas
- Departamento de Química, Universidad de Guanajuato, Noria Alta s/n C.P. 36050, Guanajuato, Gto. México
| | - Thomas Heine
- School of Engineering and Science, Jacobs University Bremen, 28759 Bremen, Germany
| | - Gabriel Merino
- Departamento de Química, Universidad de Guanajuato, Noria Alta s/n C.P. 36050, Guanajuato, Gto. México
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16
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Ghosh D, Periyasamy G, Pati SK. Density functional theoretical investigation of the aromatic nature of BN substituted benzene and four ring polyaromatic hydrocarbons. Phys Chem Chem Phys 2011; 13:20627-36. [PMID: 21935536 DOI: 10.1039/c1cp22104c] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We have studied the topological and local aromaticity of BN-substituted benzene, pyrene, chrysene, triphenylene and tetracene molecules. The nucleus-independent chemical shielding (NICS), harmonic oscillator model of aromaticity (HOMA), para-delocalization index (PDI) and aromatic fluctuation index (FLU) have been calculated to quantify aromaticity in terms of magnetic and structural criteria. We find that charge separations due to the introduction of heteroatoms largely affect both the local and topological aromaticity of these molecules. Our studies show that the presence of any kind of heteroatom in the ring not only reduces the local delocalization in the six membered ring, but also affects strongly the topological aromaticity. In fact, the relative orders of the topological and local aromaticity depend strongly on the position of the heteroatoms in the structure. In general, more ring shared BN containing molecules are less aromatic than the less ring shared BN molecules. In addition our results provide evidence that the structural stability of the molecule is dominated by the σ bond rather than the π bond.
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Affiliation(s)
- Dibyajyoti Ghosh
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O, Bangalore-560 064, India
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17
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Fliegl H, Taubert S, Lehtonen O, Sundholm D. The gauge including magnetically induced current method. Phys Chem Chem Phys 2011; 13:20500-18. [DOI: 10.1039/c1cp21812c] [Citation(s) in RCA: 253] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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18
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Steinmann SN, Mo Y, Corminboeuf C. How do electron localization functions describe π-electron delocalization? Phys Chem Chem Phys 2011; 13:20584-92. [DOI: 10.1039/c1cp21055f] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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19
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Islas R, Martínez-Guajardo G, Jiménez-Halla JOC, Solà M, Merino G. Not All That Has a Negative NICS Is Aromatic: The Case of the H-Bonded Cyclic Trimer of HF. J Chem Theory Comput 2010. [DOI: 10.1021/ct100098c] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rafael Islas
- Departamento de Química, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Col. Noria Alta s/n C.P. 36050, Guanajuato, Gto., México, and Institut de Química Computacional and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia, Spain
| | - Gerardo Martínez-Guajardo
- Departamento de Química, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Col. Noria Alta s/n C.P. 36050, Guanajuato, Gto., México, and Institut de Química Computacional and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia, Spain
| | - J. Oscar C. Jiménez-Halla
- Departamento de Química, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Col. Noria Alta s/n C.P. 36050, Guanajuato, Gto., México, and Institut de Química Computacional and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia, Spain
| | - Miquel Solà
- Departamento de Química, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Col. Noria Alta s/n C.P. 36050, Guanajuato, Gto., México, and Institut de Química Computacional and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia, Spain
| | - Gabriel Merino
- Departamento de Química, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Col. Noria Alta s/n C.P. 36050, Guanajuato, Gto., México, and Institut de Química Computacional and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia, Spain
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Fernández I, Bickelhaupt FM, Cossío FP. Double group transfer reactions: role of activation strain and aromaticity in reaction barriers. Chemistry 2010; 15:13022-32. [PMID: 19852009 DOI: 10.1002/chem.200902024] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Double group transfer (DGT) reactions, such as the bimolecular automerization of ethane plus ethene, are known to have high reaction barriers despite the fact that their cyclic transition states have a pronounced in-plane aromatic character, as indicated by NMR spectroscopic parameters. To arrive at a way of understanding this somewhat paradoxical and incompletely understood phenomenon of high-energy aromatic transition states, we have explored six archetypal DGT reactions using density functional theory (DFT) at the OLYP/TZ2P level. The main trends in reactivity are rationalized using the activation strain model of chemical reactivity. In this model, the shape of the reaction profile DeltaE(zeta) and the height of the overall reaction barrier DeltaE( not equal)=DeltaE(zeta=zeta(TS)) is interpreted in terms of the strain energy DeltaE(strain)(zeta) associated with deforming the reactants along the reaction coordinate zeta plus the interaction energy DeltaE(int)(zeta) between these deformed reactants: DeltaE(zeta)=DeltaE(strain)(zeta)+DeltaE(int)(zeta). We also use an alternative fragmentation and a valence bond model for analyzing the character of the transition states.
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Affiliation(s)
- Israel Fernández
- Departamento de Química Orgánica, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain.
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21
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Zubarev DY, Boldyrev AI. Multiple Aromaticity, Multiple Antiaromaticity, and Conflicting Aromaticity in Planar Clusters. NANOCLUSTERS - A BRIDGE ACROSS DISCIPLINES 2010. [DOI: 10.1016/b978-0-444-53440-8.00005-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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22
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Feixas F, Matito E, Solà M, Poater J. Patterns of π-electron delocalization in aromatic and antiaromatic organic compounds in the light of Hückel's 4n + 2 rule. Phys Chem Chem Phys 2010; 12:7126-37. [DOI: 10.1039/b924972a] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Jana A, Sen S, Roesky H, Schulzke C, Dutta S, Pati S. End-On Nitrogen Insertion of a Diazo Compound into a Germanium(II) Hydrogen Bond and a Comparable Reaction with Diethyl Azodicarboxylate. Angew Chem Int Ed Engl 2009; 48:4246-8. [DOI: 10.1002/anie.200900617] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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24
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Jana A, Sen S, Roesky H, Schulzke C, Dutta S, Pati S. End-on-Stickstoffinsertion einer Diazoverbindung in eine GeII-H-Bindung und eine vergleichbare Reaktion mit Azodicarbonsäurediethylester. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200900617] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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25
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Dutta S, Manna AK, Pati SK. Intrinsic half-metallicity in modified graphene nanoribbons. PHYSICAL REVIEW LETTERS 2009; 102:096601. [PMID: 19392544 DOI: 10.1103/physrevlett.102.096601] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Indexed: 05/25/2023]
Abstract
We perform first-principles calculations based on density functional theory to study quasi-one-dimensional edge-passivated (with hydrogen) zigzag graphene nanoribbons of various widths with chemical dopants, boron and nitrogen, keeping the whole system isoelectronic. The gradual increase in doping concentration takes the system finally to zigzag boron nitride nanoribbons (ZBNNRs). Our study reveals that for all doping concentrations the systems stabilize in antiferromagnetic ground states. Doping concentrations and dopant positions regulate the electronic structure of the nanoribbons, exhibiting both semiconducting and half-metallic behaviors as a response to the external electric field. Interestingly, our results show that ZBNNRs with a terminating polyacene unit exhibit half-metallicity irrespective of the ribbon width as well as applied electric field, opening a huge possibility in spintronics device applications.
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Affiliation(s)
- Sudipta Dutta
- Theoretical Sciences Unit and DST Unit on Nanoscience, Jawaharlal Nehru Center for Advanced Scientific Research Jakkur Campus, Bangalore 560 064, India
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26
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Srinivasu K, Chandrakumar KRS, Ghosh SK. Computational Investigation of Hydrogen Adsorption by Alkali-Metal-Doped Organic Molecules: Role of Aromaticity. Chemphyschem 2009; 10:427-35. [DOI: 10.1002/cphc.200800520] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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27
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Mallajosyula SS, Parida P, Pati SK. Organometallic vanadium-borazine systems: efficient one-dimensional half-metallic spin filters. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b810089f] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Mohakud S, Pati SK. Large carrier mobilities in octathio[8]circulene crystals: a theoretical study. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b901014a] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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29
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Angeli C, Malrieu JP. Aromaticity: an ab Initio Evaluation of the Properly Cyclic Delocalization Energy and the π-Delocalization Energy Distortivity of Benzene. J Phys Chem A 2008; 112:11481-6. [DOI: 10.1021/jp805870r] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Celestino Angeli
- Dipartimento di Chimica, Università di Ferrara, Via Borsari 46, I-44100 Ferrara, Italy, and Laboratoire de Chimie et Physique Quantiques, UMR 5625 du CNRS, IRSAMC, Université Paul Sabatier, 118 Rte de Narbonne, 31062 Toulouse, France
| | - Jean-Paul Malrieu
- Dipartimento di Chimica, Università di Ferrara, Via Borsari 46, I-44100 Ferrara, Italy, and Laboratoire de Chimie et Physique Quantiques, UMR 5625 du CNRS, IRSAMC, Université Paul Sabatier, 118 Rte de Narbonne, 31062 Toulouse, France
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30
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Timoshkin AY, Schaefer HF. Theoretical Studies of [MYR2] n Isomers (M = B, Al, Ga; Y = N, P, As; R = H, CH3): Structures and Energetics of Monomeric and Dimeric Compounds (n = 1, 2). J Phys Chem A 2008; 112:13180-96. [DOI: 10.1021/jp801799f] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alexey Y. Timoshkin
- Inorganic Chemistry Group, Department of Chemistry, St. Petersburg State University, University Pr. 26, Old Peterhof, 198504, Russia
| | - Henry F. Schaefer
- Center for Computational Chemistry, University of Georgia, Athens, Georgia 30602
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31
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Yin B, Wang G, Sa N, Huang Y. Bonding analysis and stability on alternant B16N16 cage and its dimers. J Mol Model 2008; 14:789-95. [PMID: 18493803 DOI: 10.1007/s00894-008-0303-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Accepted: 03/12/2008] [Indexed: 11/29/2022]
Abstract
Bonding analysis is performed on alternant B(16)N(16) cage based on a combined study of DFT with NBO method. The main feature of such analysis is the separation of bonding structure into two components: sigma skeleton and pi bond system. Each component is further decomposed into contributions from various NBOs, thus we obtain the details of bonding interactions of every BN unit. Based on these results, relative stability of four covalent dimers of B(16)N(16) is predicted and this prediction is verified by DFT calculations. So the possibility of forecasting properties of oligomers just from analysis on monomer is highlighted in this way.
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Affiliation(s)
- Bing Yin
- College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic China
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32
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Pierrefixe SCAH, Bickelhaupt FM. Aromaticity and Antiaromaticity in 4-, 6-, 8-, and 10-Membered Conjugated Hydrocarbon Rings. J Phys Chem A 2008; 112:12816-22. [DOI: 10.1021/jp800514n] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Simon C. A. H. Pierrefixe
- Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling, Scheikundig Laboratorium der Vrije Universiteit, De Boelelaan 1083, NL-1081 HV Amsterdam, The Netherlands
| | - F. Matthias Bickelhaupt
- Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling, Scheikundig Laboratorium der Vrije Universiteit, De Boelelaan 1083, NL-1081 HV Amsterdam, The Netherlands
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33
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The proton transfer reaction in malonaldehyde derivatives: Substituent effects and quasi-aromaticity of the proton bridge. Chem Phys 2007. [DOI: 10.1016/j.chemphys.2007.09.016] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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34
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Del Bene JE, Elguero J, Alkorta I, Yañez M, Mó O. An ab initio study of 15N-11B spin-spin coupling constants for borazine and selected derivatives. J Phys Chem A 2007; 110:9959-66. [PMID: 16898700 DOI: 10.1021/jp0628737] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ab initio equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) calculations have been performed to investigate substituent effects on coupling constants for borazine and selected substituted borazines. For molecules in which F atoms are not bonded to adjacent atoms in the ring, F substitution increases the one-bond (11)B-(15)N coupling constants involving the atom at which substitution occurs but leaves the remaining one-bond B-N coupling constants essentially unchanged. For these molecules, the magnitudes of one-bond B-N coupling constants are only slightly dependent on the number of F atoms present. Fluorine substitution at adjacent B and N atoms in the borazine ring further increases the one-bond B-N coupling constant involving the substituted atoms and has the same effect on the other one-bond coupling constants as observed for corresponding molecules in which substitution occurs at alternate sites. In contrast to the effect of F substitution, substitution of Li at either N or B decreases one-bond B-N coupling constants relative to borazine. The effects of F and Li substitution on one-bond B-N coupling constants for borazine are similar to F and Li substitution effects on (13)C-(13)C coupling constants for benzene.
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Affiliation(s)
- Janet E Del Bene
- Department of Chemistry, Youngstown State University, Youngstown, Ohio 44555, Instituto de Química, Médica, CSIC, Juan de la Cierva, 3, E-28006 Madrid, Spain.
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35
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Pierrefixe SCAH, Bickelhaupt FM. Aromaticity: molecular-orbital picture of an intuitive concept. Chemistry 2007; 13:6321-8. [PMID: 17577248 DOI: 10.1002/chem.200700206] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Geometry is one of the primary and most direct indicators of aromaticity and antiaromaticity: a regular structure with delocalized double bonds (e.g., benzene) is symptomatic of aromaticity, whereas a distorted geometry with localized double bonds (e.g., 1,3-cyclobutadiene) is characteristic of antiaromaticity. Here, we present a molecular-orbital (MO) model of aromaticity that explains, in terms of simple orbital-overlap arguments, why this is so. Our MO model is based on accurate Kohn-Sham DFT analyses of the bonding in benzene, 1,3-cyclobutadiene, cyclohexane, and cyclobutane, and how the bonding mechanism is affected if these molecules undergo geometrical deformations between regular, delocalized ring structures, and distorted ones with localized double bonds. We show that the propensity of the pi electrons is always, that is, in both the aromatic and antiaromatic molecules, to localize the double bonds, against the delocalizing force of the sigma electrons. More importantly, we show that the pi electrons nevertheless decide about the localization or delocalization of the double bonds. A key component of our model for uncovering and resolving this seemingly contradictory situation is to analyze the bonding in the various model systems in terms of two interpenetrating fragments that preserve, in good approximation, their geometry along the localization/delocalization modes.
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Affiliation(s)
- Simon C A H Pierrefixe
- Afdeling Theoretische Chemie, Scheikundig Laboratorium der Vrije Universiteit, De Boelelaan 1083, NL-1081 HV Amsterdam, The Netherlands
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36
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Seal P, Chakrabarti S. Is Nucleus-Independent Chemical Shift Scan a Reliable Aromaticity Index for Planar Heteroatomic Ring Systems? J Phys Chem A 2007; 111:9988-94. [PMID: 17803289 DOI: 10.1021/jp074440p] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Density functional theoretical investigation has been performed to explore the reliability of the nucleus-independent chemical shift (NICS) scheme in assessing aromatic behavior of some planar six-membered heteroatomic systems. It has been observed that the NICS scan and the diamagnetic and paramagnetic contributions of the in-plane and out-of-plane components are quite reliable in assessing any aromatic or antiaromatic behavior in borazine. However, for boraphosphabenzene, the aromatic stabilization energy is too small to consider it as an aromatic system but the NICS scans and the homodesmotic reactions suggest an opposite trend. Interestingly, in the case of alumazene, a very shallow minimum is observed for the out-of-plane component, which suggests the presence of weak diamagnetic ring current. However, the diamagnetic and paramagnetic contribution curves to the out-of-plane component for alumazene clearly reveal a net paramagnetic contribution. Thus we may surmise that apart from the single NICS value, the NICS scan also is not a very authentic tool for the assessment of aromaticity of planar six-membered heteroatomic systems.
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Affiliation(s)
- Prasenjit Seal
- Department of Chemistry, University of Calcutta, 92, A.P.C.Ray Road, Kolkata 700 009, India
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37
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Palusiak M, Simon S, Solà M. Interplay between intramolecular resonance-assisted hydrogen bonding and aromaticity in o-hydroxyaryl aldehydes. J Org Chem 2007; 71:5241-8. [PMID: 16808511 DOI: 10.1021/jo060591x] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this work, we analyze a series of o-hydroxyaryl aldehydes to discuss the interrelation between the resonance-assisted hydrogen bond (RAHB) formation and the aromaticity of the adjacent aromatic rings. As compared to the nonaromatic reference species (malonaldehyde), the studied compounds can be separated into two groups: first, the set of systems that have a stronger RAHB than that of the reference species, for which there is a Kekulé structure with a localized double CC bond linking substituted carbon atoms; and second, the systems having a weaker RAHB than that of the reference species, for which only pi-electrons coming from a localized Clar pi-sextet can be involved in the RAHB. As to aromaticity, there is a clear reduction of aromaticity in the substituted ipso ring for the former group of systems due to the formation of the RAHB, while for the latter group of species only a slight change of local aromaticity is observed in the substituted ipso ring.
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Affiliation(s)
- Marcin Palusiak
- Institut de Química Computacional and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia, Spain
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38
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Seal P, Chakrabarti S. Reply to “Comment on ‘Origin of the Nonplanarity of Tetrafluoro Cyclobutadiene, C4F4'”. J Phys Chem A 2007. [DOI: 10.1021/jp0711141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Prasenjit Seal
- Department of Chemistry, University of Calcutta, 92 A.P.C. Ray Road, Kolkata 700 009, India
| | - Swapan Chakrabarti
- Department of Chemistry, University of Calcutta, 92 A.P.C. Ray Road, Kolkata 700 009, India
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39
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G2, G3, and complete basis set calculations of the thermodynamic properties of two isomers of diazadiboretidine, cyclo-B2N2H4. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.theochem.2006.12.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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40
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Richard RM, Ball DW. G2, G3, and complete basis set calculations of optimized geometries, vibrational frequencies, and thermodynamic properties of azatriboretidine and triazaboretidine. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.theochem.2006.11.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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41
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Seal P, Chakrabarti S. Origin of the Nonplanarity of Tetrafluoro Cyclobutadiene, C4F4. J Phys Chem A 2007; 111:715-8. [PMID: 17249763 DOI: 10.1021/jp067828d] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Density functional theory as well as Møller-Plesset investigations has been carried out on tetrafluoro cyclobutadiene, C4F4, to explore the origin of its nonplanarity. Although Petersson et al. (Petersson, E. J.; Fanuele, J. C.; Nimlos, M. R.; Lemal, D. M.; Ellison, G. B.; Radziszewski, J. G. J. Am. Chem. Soc. 1997, 119, 11122-11123) had earlier predicted a nonplanar geometry of this compound on the basis of spectral and bond orbital analysis, the explanation of the same from a more fundamental point of view is still missing. In the present study, we provide a heuristic explanation for the origin of nonplanarity of C4F4. The two major driving forces behind this nonplanar geometry are the unusual aromaticity of this cyclic homoatomic 4pi electron system and the second-order Jahn-Teller effect (SOJTE). These driving forces can well be explained by various energy and density parameters and also by nucleus-independent chemical shift (NICS) values. Aromaticity of a cyclic homoatomic 4pi electron system is quite remarkable. The enhancement of pi- delocalization as evidenced from molecular orbital analysis may be attributed to s-ppi mixing in nonplanar C4F4.
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Affiliation(s)
- Prasenjit Seal
- Department of Chemistry, University of Calcutta, 92, A. P. C. Ray Road, Kolkata 700 009, India
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42
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Datta A, Pati SK. Limit to puckering of benzene with sterically crowded molecules: Hexaferrocenylbenzene. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.11.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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43
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Mallajosyula SS, Datta A, Pati SK. Aromatic Superclusters from All-Metal Aromatic and Antiaromatic Monomers, [Al4]2-and [Al4]4-. J Phys Chem B 2006; 110:20098-101. [PMID: 17034180 DOI: 10.1021/jp064821n] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Calculations on the structures of dimers of all-metal aromatic and anti-aromatic molecules such as (Al4(2-)) and (Al4(4-)) reveal that, unlike their organic counterparts such as benzene and cyclobutadiene which form pi-stacked complexes, these molecules form new clusters with no reminiscence of the original units. These clusters have a very large binding energy and can be further stabilized through charge-balance by counterions and solvents.
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Lin YC, Sundholm D, Jusélius J. On the Aromaticity of the Planar Hydrogen-Bonded (HF)3 Trimer. J Chem Theory Comput 2006; 2:761-4. [DOI: 10.1021/ct050297x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ying-Chan Lin
- Department of Chemistry, University of Helsinki, P. O. Box 55 (A. I. Virtanens plats 1), FIN-00014, Helsinki, Finland
| | - Dage Sundholm
- Department of Chemistry, University of Helsinki, P. O. Box 55 (A. I. Virtanens plats 1), FIN-00014, Helsinki, Finland
| | - Jonas Jusélius
- Department of Chemistry, University of Tromsø, N-9037 Tromsø, Norway
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Zubarev DY, Boldyrev AI. Comprehensive analysis of chemical bonding in boron clusters. J Comput Chem 2006; 28:251-68. [PMID: 17111395 DOI: 10.1002/jcc.20518] [Citation(s) in RCA: 195] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We present a comprehensive analysis of chemical bonding in pure boron clusters. It is now established in joint experimental and theoretical studies that pure boron clusters are planar or quasi-planar at least up to twenty atoms. Their planarity or quasi-planarity was usually discussed in terms of pi-delocalization or pi-aromaticity. In the current article, we demonstrated that one cannot ignore sigma-electrons and that the presence of two-center two-electron (2c--2e) peripheral B--B bonds together with the globally delocalized sigma-electrons must be taken into consideration when the shape of pure boron cluster is discussed. The global aromaticity (or global antiaromaticity) can be assigned on the basis of the 4n+2 (or 4n) electron counting rule for either pi- or sigma-electrons in the planar structures. We showed that pure boron clusters could have double (sigma- and pi-) aromaticity (B3-, B4, B5+, B6(2+), B7+, B7-, B8, B(8)2-, B9-, B10, B11+, B12, and B13+), double (sigma- and pi-) antiaromaticity (B6(2-), B15), or conflicting aromaticity (B5-,sigma-antiaromatic and pi-aromatic and B14, sigma-aromatic and pi-antiaromatic). Appropriate geometric fit is also an essential factor, which determines the shape of the most stable structures. In all the boron clusters considered here, the peripheral atoms form planar cycles. Peripheral 2c--2e B--B bonds are built up from s to p hybrid atomic orbitals and this enforces the planarity of the cycle. If the given number of central atoms (1, 2, 3, or 4) can perfectly fit the central cavity then the overall structure is planar. Otherwise, central atoms come out of the plane of the cycle and the overall structure is quasi-planar.
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Affiliation(s)
- Dmitry Yu Zubarev
- Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, UT 84322-0300, USA
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