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Abstract
Heteroatom-centered diradical(oid)s have been in the focus of molecular main group chemistry for nearly 30 years. During this time, the diradical concept has evolved and the focus has shifted to the rational design of diradical(oid)s for specific applications. This review article begins with some important theoretical considerations of the diradical and tetraradical concept. Based on these theoretical considerations, the design of diradical(oid)s in terms of ligand choice, steric, symmetry, electronic situation, element choice, and reactivity is highlighted with examples. In particular, heteroatom-centered diradical reactions are discussed and compared with closed-shell reactions such as pericyclic additions. The comparison between closed-shell reactivity, which proceeds in a concerted manner, and open-shell reactivity, which proceeds in a stepwise fashion, along with considerations of diradical(oid) design, provides a rational understanding of this interesting and unusual class of compounds. The application of diradical(oid)s, for example in small molecule activation or as molecular switches, is also highlighted. The final part of this review begins with application-related details of the spectroscopy of diradical(oid)s, followed by an update of the heteroatom-centered diradical(oid)s and tetraradical(oid)s published in the last 10 years since 2013.
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Affiliation(s)
- Alexander Hinz
- Institut für Anorganische Chemie (AOC), Karlsruher Institut für Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
| | - Jonas Bresien
- Institut für Chemie, Universität Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
| | - Frank Breher
- Institut für Anorganische Chemie (AOC), Karlsruher Institut für Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
| | - Axel Schulz
- Institut für Chemie, Universität Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
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2
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Zhu B, Song Y, Zhu J, Rauhut G, Jiang J, Zeng X. FP(μ-N) 2 S: A Sulfur-Pnictogen Four-Membered Ring with 6π Electrons. Chemistry 2023; 29:e202300251. [PMID: 37261435 DOI: 10.1002/chem.202300251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 04/28/2023] [Accepted: 06/01/2023] [Indexed: 06/02/2023]
Abstract
The new 6π-electron four-membered ring compound 3-fluoro-1λ2 ,2,4,3λ3 -thiadiazaphosphetidine, FP(μ-N)2 S, has been generated in the gas phase through high-vacuum flash pyrolysis (HVFP) of thiophosphoryl diazide, FP(S)(N3 )2 , at 1000 K. Subsequent isolation of FP(μ-N)2 S in cryogenic matrices (Ar, Ne, and N2 ) allows its characterization with matrix-isolation IR and UV-vis spectroscopy by combination with 15 N-isotope labeling and computations at the CCSD(T)-F12a/VTZ-F12 level of theory. Upon visible-light irradiation at 550 nm, this cyclic compound undergoes ring-opening to the thiazyl isomer FPNSN, followed by dissociation to FP and SN2 under subsequent UV-irradiation at 365 nm. In sharp contrast to the square planar structure for the isolobal four-membered ring S2 N2 , a puckered structure with significant biradical character has been found for FP(μ-N)2 S.
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Affiliation(s)
- Bifeng Zhu
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, 200433, China
| | - Yanlin Song
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Jun Zhu
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Guntram Rauhut
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, Stuttgart, 70569, Germany
| | - Junjie Jiang
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, 200433, China
| | - Xiaoqing Zeng
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, 200433, China
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3
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Al-Yassiri MAH. Tubular Magnetic Shielding Scan (TMSS): A New Technique for Molecular Space Exploration. (i) The Case of Aromaticity of Benzene and [ n]Paracyclophanes. J Phys Chem A 2023; 127:6614-6627. [PMID: 37501257 DOI: 10.1021/acs.jpca.3c03041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Both traditional and novel techniques were employed in this work for magnetic shielding evaluation to shed new light on the magnetic and aromaticity properties of benzene and 12 [n]paracyclophanes with n = 3-14. Density functional theory (DFT) with the B3LYP functional and all-electron Jorge-ATZP and x2c-TZVPPall-s basis sets was utilized for geometry optimization and magnetic shielding calculations, respectively. Additionally, the 6-311+G(d,p) basis set was incorporated for the purpose of comparing the magnetic shielding results. In addition to traditional evaluations such as NICS/NICSzz-Scan, and 2D-3D σiso(r)/σzz(r) maps, two new techniques were implemented: bendable grids (BGs) and cylindrical grids (CGs) of ghost atoms (Bqs). BGs allow for the recording of magnetic shielding from the bent ring levels of [n]pCPs, while CGs provide tubular magnetic shielding scan (TMSS) maps detailing the magnetic shielding from a cylindrical region above and below the ring frame. Our findings suggest that smaller [n]pCPs with n < 6 exhibit deviations in the magnetic shielding above and below the ring, indicating a broken electron delocalization under the ring. In contrast, larger [n]pCPs tend to behave similarly to benzene in terms of magnetic shielding. Moreover, we found that shorter polymethylene chains of [n]pCPs exhibit significantly higher magnetic shielding interactions with the ring. Both of the above techniques offer new and promising tools for characterizing nonplanar aromatic compounds, thereby contributing to a deeper understanding of their magnetic and electronic properties.
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Affiliation(s)
- Muntadar A H Al-Yassiri
- Department of Chemistry, College of Science, University of Baghdad, Al-Jadirya, Baghdad 10071, Iraq
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4
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Al-Yassiri MAH. Spherical Aromaticity of Tetrahedral Pnictogens through Off-Nucleus Isotropic Magnetic Shielding. Chemphyschem 2022; 23:e202200271. [PMID: 35768283 DOI: 10.1002/cphc.202200271] [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: 04/19/2022] [Revised: 06/10/2022] [Indexed: 11/08/2022]
Abstract
This work revealed the spherical aromaticity of some inorganic E4 cages and their protonated E4 H+ ions (E=N, P, As, Sb, and Bi). For this purpose, we employed several evaluations like (0D-1D) nucleus independent chemical shift (NICS), multidimensional (2D-3D) off-nucleus isotropic shielding σiso (r), and natural bond orbital (NBO) analysis. The magnetic calculations involved gauge-including atomic orbitals (GIAO) with two density functionals B3LYP and WB97XD, and basis sets of Jorge-ATZP, 6-311+G(d,p), and Lanl2DZp. The Jorge-ATZP basis set showed the best consistency. Our findings disclosed non-classical aromatic characters in the above molecules, which decreased from N to Bi cages. Also, the results showed more aromaticity in E4 than E4 H+ . The NBO analysis attributed the aromaticity in the above molecules to the residual density of the overlapping σ-bonding orbitals. So, the aromaticity in these molecules is unlike the classical aromaticity that is associated with electron delocalization. Scanning 1D σiso (r) variation along E-E bonds indicated a lowering in the shielding trend from N to Bi cages. The 3D results showed a similar decrease in the relative volumetric diffusion of the magnetic activity, whereas the volumetric ratio of V1ppm /V2ppm is almost constant for all the E4 cages.
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5
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Karadakov PB, Preston N. Aromaticity reversals and their effect on bonding in the low-lying electronic states of cyclooctatetraene. Phys Chem Chem Phys 2021; 23:24750-24756. [PMID: 34710205 DOI: 10.1039/d1cp04394c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aromaticity reversals and their effect on chemical bonding in the low-lying electronic states of cyclooctatetraene (COT) are investigated through a visual approach which examines the variations in isotropic magnetic shielding in the space surrounding the molecule. The ground state (S0) of COT is shown to be strongly antiaromatic at the π-bond-shifting transition state (TS), a regular octagon of D8h symmetry; S0 antiaromaticity decreases at the D4h planar bond-alternating tub-to-tub ring-inversion TS but traces of it are shown to persist even at the tub-shaped D2d local minimum geometry. The lowest triplet (T1) and first singlet excited (S1) states of COT are found to have very similar D8h geometries and visually indistinguishable shielding distributions closely resembling that in benzene and indicating similarly high levels of aromaticity. Unexpectedly, COT diverges from its antiaromatic predecessor, cyclobutadiene, in the properties of the second singlet excited state (S2): In cyclobutadiene S2 is antiaromatic but in COT this state turns out to be strongly aromatic, with a shielding distribution closely following that around S2 benzene.
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Affiliation(s)
- Peter B Karadakov
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
| | - Nicholas Preston
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
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6
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Stauch T, Ganoe B, Wong J, Lee J, Rettig A, Liang J, Li J, Epifanovsky E, Head-Gordon T, Head-Gordon M. Molecular magnetisabilities computed via finite fields: assessing alternatives to MP2 and revisiting magnetic exaltations in aromatic and antiaromatic species. Mol Phys 2021; 119. [DOI: 10.1080/00268976.2021.1990426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Tim Stauch
- Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, CA, USA
| | - Brad Ganoe
- Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, CA, USA
| | - Jonathan Wong
- Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, CA, USA
| | - Joonho Lee
- Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, CA, USA
| | - Adam Rettig
- Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, CA, USA
| | - Jiashu Liang
- Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, CA, USA
| | - Jie Li
- Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, CA, USA
| | | | - Teresa Head-Gordon
- Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, CA, USA
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, USA
| | - Martin Head-Gordon
- Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, CA, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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7
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Al‐Yassiri MAH. Bonding, Aromaticity and Isomerization of Furfuraldehyde through Off-Nucleus Isotropic Magnetic Shielding. ChemistryOpen 2021; 10:976-985. [PMID: 34596975 PMCID: PMC8485829 DOI: 10.1002/open.202100202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/02/2021] [Indexed: 11/11/2022] Open
Abstract
Off-nucleus isotropic magnetic shielding (σiso (r)) and multi-points nucleus independent chemical shift (NICS(0-2 Å)) index were utilized to find the impacts of the isomerization of gas-phase furfuraldehyde (FD) on bonding and aromaticity of FD. Multidimensional (1D to 3D) grids of ghost atoms (bqs) were used as local magnetic probes to evaluate σiso (r) through gauge-including atomic orbitals (GIAO) at density functional theory (DFT) and B3LYP functional/6-311+G(d,p) basis set level of theory. 1D σiso (r) responses along each bond of FD were examined. Also, a σiso (r) 2D-scan was performed to obtain σiso (r) behavior at vertical heights of 0-1 Å above the FD plane in its cis, transition state (TS) and trans forms. New techniques for evaluating 2D σiso (r) cross-sections are also included. Our findings showed that bonds in cyclic and acyclic parts of FD are dissimilar. Unlike the C-O bond of furanyl, the C=O bond of the formyl group is magnetically different. C-C and C-H bonds in furanyl are found similar to those in aromatic rings. A unique σiso (r) trend was observed for the C2 -C6 bond during FD isomerization. Based on NICS(0-2 Å) values, the degree of aromaticity follows the order of cis FD
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8
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Karadakov PB, VanVeller B. Magnetic shielding paints an accurate and easy-to-visualize portrait of aromaticity. Chem Commun (Camb) 2021; 57:9504-9513. [PMID: 34546260 DOI: 10.1039/d1cc03701c] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chemists are trained to recognize aromaticity semi-intuitively, using pictures of resonance structures and Frost-Musulin diagrams, or simple electron-counting rules such as Hückel's 4n + 2/4n rule. To quantify aromaticity one can use various aromaticity indices, each of which is a number reflecting some experimentally measured or calculated molecular property, or some feature of the molecular wavefunction, which often has no visual interpretation or may not have direct chemical relevance. We show that computed isotropic magnetic shielding isosurfaces and contour plots provide a feature-rich picture of aromaticity and chemical bonding which is both quantitative and easy-to-visualize and interpret. These isosurfaces and contour plots make good chemical sense as at atomic positions they are pinned to the nuclear shieldings which are experimentally measurable through chemical shifts. As examples we discuss the archetypal aromatic and antiaromatic molecules of benzene and square cyclobutadiene, followed by modern visual interpretations of Clar's aromatic sextet theory, the aromaticity of corannulene and heteroaromaticity.
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Affiliation(s)
- Peter B Karadakov
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - Brett VanVeller
- Department of Chemistry, Iowa State University Ames, IA 50011, USA.
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9
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Karadakov PB, Di M, Cooper DL. Excited-State Aromaticity Reversals in Möbius Annulenes. J Phys Chem A 2020; 124:9611-9616. [PMID: 33155798 DOI: 10.1021/acs.jpca.0c08594] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
It is suggested that Möbius annulenes follow a rule similar to Baird's rule such that the 4n and 4n + 2 criteria for Möbius electronic ground-state aromaticity and antiaromaticity are reversed in the lowest triplet and first singlet excited electronic states. Support comes from an investigation of aromaticity in the ground (S0), lowest triplet (T1), and first singlet excited (S1) electronic states of the Möbius-aromatic cyclononatetraenyl cation, C9H9+, using isotropic magnetic shielding isosurfaces calculated with state-optimized complete-active-space self-consistent field wave functions constructed from gauge-including atomic orbitals. Examination of these isosurfaces demonstrates that while the S0 state of C9H9+ is aromatic, the T1 and S1 states are antiaromatic.
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Affiliation(s)
- Peter B Karadakov
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| | - Make Di
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| | - David L Cooper
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K
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10
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Are Multicentre Bond Indices and Related Quantities Reliable Predictors of Excited-State Aromaticity? Molecules 2020; 25:molecules25204791. [PMID: 33086580 PMCID: PMC7587523 DOI: 10.3390/molecules25204791] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/04/2020] [Accepted: 10/16/2020] [Indexed: 12/02/2022] Open
Abstract
Systematic scrutiny is carried out of the ability of multicentre bond indices and the NOEL-based similarity index dAB to serve as excited-state aromaticity criteria. These indices were calculated using state-optimized complete active-space self-consistent field wavefunctions for several low-lying singlet and triplet states of the paradigmatic molecules of benzene and square cyclobutadiene and the inorganic ring S2N2. The comparison of the excited-state indices with aromaticity trends for individual excited states suggested by the values of magnetic aromaticity criteria show that whereas the indices work well for aromaticity reversals between the ground singlet and first triplet electronic states, addressed by Baird’s rule, there are no straightforward parallels between the two sets of data for singlet excited states. The problems experienced while applying multicentre bond indices and dAB to singlet excited states are explained by the loss of the information inherently present in wavefunctions and/or pair densities when calculating the first-order density matrix.
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11
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Lampkin BJ, Karadakov PB, VanVeller B. Detailed Visualization of Aromaticity Using Isotropic Magnetic Shielding. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202008362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | | | - Brett VanVeller
- Department of Chemistry Iowa State University Ames IA 50011 USA
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12
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Lampkin BJ, Karadakov PB, VanVeller B. Detailed Visualization of Aromaticity Using Isotropic Magnetic Shielding. Angew Chem Int Ed Engl 2020; 59:19275-19281. [PMID: 33448542 DOI: 10.1002/anie.202008362] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Indexed: 11/07/2022]
Abstract
For many years, Clar's aromatic sextet theory has served as a qualitative method for assessing the aromatic character of polycyclic aromatic hydrocarbons. A new approach, based on the calculation of isotropic magnetic shielding (IMS) contour plots, is shown to provide a feature-rich picture of aromaticity that is both quantitative yet still easily interpreted. Chemists are visual creatures who are adept at discerning reactivity and chemical behavior from molecular structures. To quote Roald Hoffmann, "People like pictures. Chemists live off them." Thus, the detailed image analysis we present simultaneously provides quantitative assessment of electronic structure, which is still easy-to-understand through visual inspection, embedded in an aesthetically appealing and intuitive picture that draws the reader in. We provide novel computed IMS contour plots for a representative selection of aromatic molecules. Where Clar's static drawings capture only a partial sketch of the electronic properties of a molecule, IMS contour plots present a detailed, global landscape of a molecule that sums all possible resonance structures. This novel analysis allows us to correct certain drawbacks of Clar's analysis with respect to polycyclic aromatics and quantitatively assess the bonding and electronic structure of acene hydrocarbons.
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Affiliation(s)
- Bryan J Lampkin
- Department of Chemistry, Iowa State University, Ames, IA, 50011, USA
| | - Peter B Karadakov
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | - Brett VanVeller
- Department of Chemistry, Iowa State University, Ames, IA, 50011, USA
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13
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Slanina T, Ayub R, Toldo J, Sundell J, Rabten W, Nicaso M, Alabugin I, Fdez Galván I, Gupta AK, Lindh R, Orthaber A, Lewis RJ, Grönberg G, Bergman J, Ottosson H. Impact of Excited-State Antiaromaticity Relief in a Fundamental Benzene Photoreaction Leading to Substituted Bicyclo[3.1.0]hexenes. J Am Chem Soc 2020; 142:10942-10954. [PMID: 32456426 PMCID: PMC7497645 DOI: 10.1021/jacs.9b13769] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
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Benzene exhibits a rich photochemistry
which can provide access
to complex molecular scaffolds that are difficult to access with reactions
in the electronic ground state. While benzene is aromatic in its ground
state, it is antiaromatic in its lowest ππ* excited
states. Herein, we clarify to what extent relief of excited-state
antiaromaticity (ESAA) triggers a fundamental benzene photoreaction:
the photoinitiated nucleophilic addition of solvent to benzene in
acidic media leading to substituted bicyclo[3.1.0]hex-2-enes. The
reaction scope was probed experimentally, and it was found that silyl-substituted
benzenes provide the most rapid access to bicyclo[3.1.0]hexene derivatives,
formed as single isomers with three stereogenic centers in yields
up to 75% in one step. Two major mechanism hypotheses, both involving
ESAA relief, were explored through quantum chemical calculations and
experiments. The first mechanism involves protonation of excited-state
benzene and subsequent rearrangement to bicyclo[3.1.0]hexenium cation,
trapped by a nucleophile, while the second involves photorearrangement
of benzene to benzvalene followed by protonation and nucleophilic
addition. Our studies reveal that the second mechanism is operative.
We also clarify that similar ESAA relief leads to puckering of S1-state silabenzene and pyridinium ion, where the photorearrangement
of the latter is of established synthetic utility. Finally, we identified
causes for the limitations of the reaction, information that should
be valuable in explorations of similar photoreactions. Taken together,
we reveal how the ESAA in benzene and 6π-electron heterocycles
trigger photochemical distortions that provide access to complex three-dimensional
molecular scaffolds from simple reactants.
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Affiliation(s)
- Tomáš Slanina
- Department of Chemistry - Ångström Laboratory, Uppsala University, SE-751 20, Uppsala, Sweden.,Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo námĕstí 2, 16610 Prague 6, Czech Republic
| | - Rabia Ayub
- Department of Chemistry - Ångström Laboratory, Uppsala University, SE-751 20, Uppsala, Sweden
| | - Josene Toldo
- Department of Chemistry - Ångström Laboratory, Uppsala University, SE-751 20, Uppsala, Sweden
| | - Johan Sundell
- Medicinal Chemistry, Research and Early Development Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Wangchuk Rabten
- Department of Chemistry - Ångström Laboratory, Uppsala University, SE-751 20, Uppsala, Sweden
| | - Marco Nicaso
- Department of Chemistry - Ångström Laboratory, Uppsala University, SE-751 20, Uppsala, Sweden
| | - Igor Alabugin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Ignacio Fdez Galván
- Department of Chemistry - BMC, Uppsala University, SE-751 23 Uppsala, Sweden
| | - Arvind K Gupta
- Department of Chemistry - Ångström Laboratory, Uppsala University, SE-751 20, Uppsala, Sweden
| | - Roland Lindh
- Department of Chemistry - BMC, Uppsala University, SE-751 23 Uppsala, Sweden.,Uppsala Center for Computational Chemistry - UC3, Uppsala University, SE-751 23 Uppsala Sweden
| | - Andreas Orthaber
- Department of Chemistry - Ångström Laboratory, Uppsala University, SE-751 20, Uppsala, Sweden
| | - Richard J Lewis
- Medicinal Chemistry, Research and Early Development Respiratory, Inflammation and Autoimmune, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Gunnar Grönberg
- Medicinal Chemistry, Research and Early Development Respiratory, Inflammation and Autoimmune, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Joakim Bergman
- Medicinal Chemistry, Research and Early Development Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Henrik Ottosson
- Department of Chemistry - Ångström Laboratory, Uppsala University, SE-751 20, Uppsala, Sweden
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14
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Chivers T, Laitinen RS. Neutral binary chalcogen-nitrogen and ternary S,N,P molecules: new structures, bonding insights and potential applications. Dalton Trans 2020; 49:6532-6547. [PMID: 32342078 DOI: 10.1039/d0dt00807a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Early theoretical and experimental investigations of inorganic sulfur-nitrogen compounds were dominated by (a) assessments of the purported aromatic character of cyclic, binary S,N molecules and ions, (b) the unpredictable reactions of the fascinating cage compound S4N4, and (c) the unique structure and properties of the conducting polymer (SN)x. In the last few years, in addition to unexpected developments in the chemistry of well-known sulfur nitrides, the emphasis of these studies has changed to include nitrogen-rich species formed under high pressures, as well as the selenium analogues of well-known S,N compounds. Novel applications have been established or predicted for many binary S/Se,N molecules, including their use for fingerprint detection, in optoelectronic devices, as high energy-density compounds or as hydrogen-storage materials. The purpose of this perspective is to evaluate critically these new aspects of the chemistry of neutral, binary chalcogen-nitrogen molecules and to suggest experimental approaches to the synthesis of target compounds. Recently identified ternary S,N,P compounds will also be considered in light of their isoelectronic relationship with binary S,N cations.
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Affiliation(s)
- Tristram Chivers
- Department of Chemistry, University of Calgary, AB, CanadaT2N 1N4.
| | - Risto S Laitinen
- Laboratory of Inorganic Chemistry, Environmental and Chemical Engineering, University of Oulu, P. O. Box 3000, 90014, Finland.
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15
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Toldo J, El Bakouri O, Solà M, Norrby PO, Ottosson H. Is Excited-State Aromaticity a Driving Force for Planarization of Dibenzannelated 8π-Electron Heterocycles? Chempluschem 2019; 84:712-721. [PMID: 31944021 DOI: 10.1002/cplu.201900066] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 03/28/2019] [Indexed: 11/11/2022]
Abstract
Compounds with dibenzannelated heterocycles with eight π-electrons are found in a range of applications. These molecules often adopt a bent structure in the ground state (S0 ) but can become planar in the first excited states (S1 and T1 ) because of the cyclically conjugated 4nπ central ring, which fulfils the requirements for excited state aromaticity. We report on a quantum chemical investigation of the aromatic character in the S1 and T1 states of dibenzannelated seven- and six-membered heterocycles with one, two, or three heteroatoms in the 8π-electron ring. These states could have ππ* or nπ* character. We find that compounds with one or two heteroatoms in the central ring have ππ* states as their S1 and T1 states. They are to a significant degree influenced by excited state aromaticity, and their optimal structures are planar or nearly planar. Among the heteroatoms, nitrogen provides for the strongest excited state aromaticity whereas oxygen provides for the weakest, following the established trend of the S0 state. Yet, dibenzannelated seven-membered-ring compounds with N=N bonds have non-aromatic nπ* states with strongly puckered structures as their S1 and T1 states.
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Affiliation(s)
- Josene Toldo
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 530, 751 20, Uppsala, Sweden
| | - Ouissam El Bakouri
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 530, 751 20, Uppsala, Sweden
| | - Miquel Solà
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, C/ M. Aurèlia Capmany 69, 17003, Girona, Spain
| | - Per-Ola Norrby
- Early Product Development, Pharmaceutical Sciences, IMED Biotech Unit AstraZeneca, Pepparedsleden 1, 431 83, Mölndal, Sweden
| | - Henrik Ottosson
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 530, 751 20, Uppsala, Sweden
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16
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Yadav S, El Bakouri O, Jorner K, Tong H, Dahlstrand C, Solà M, Ottosson H. Exploiting the Aromatic Chameleon Character of Fulvenes for Computational Design of Baird‐Aromatic Triplet Ground State Compounds. Chem Asian J 2019; 14:1870-1878. [DOI: 10.1002/asia.201801821] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Indexed: 12/19/2022]
Affiliation(s)
- Sangeeta Yadav
- Department of Chemistry-Ångström Laboratory, Box 523Uppsala University 75120 Uppsala Sweden
| | - Ouissam El Bakouri
- Department of Chemistry-Ångström Laboratory, Box 523Uppsala University 75120 Uppsala Sweden
| | - Kjell Jorner
- Department of Chemistry-Ångström Laboratory, Box 523Uppsala University 75120 Uppsala Sweden
| | - Hui Tong
- Department of Chemistry-BMC, Box 576Uppsala University 75123 Uppsala Sweden
| | | | - Miquel Solà
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de QuímicaUniversitat de Girona c/ Maria Aurèlia Capmany 69 17003 Girona Catalonia Spain
| | - Henrik Ottosson
- Department of Chemistry-Ångström Laboratory, Box 523Uppsala University 75120 Uppsala Sweden
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