1
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Rabe A, Wang Q, Sundholm D. Unraveling the enigma of Craig-type Möbius-aromatic osmium compounds. Dalton Trans 2024; 53:10938-10946. [PMID: 38888198 DOI: 10.1039/d4dt01110d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
Nuclear magnetic resonance (NMR) chemical shifts and the magnetically induced current density (MICD) susceptibility of four osmium containing molecules have been calculated at the density functional theory (DFT) level using three relativistic levels of theory. The calculations were performed at the quasi-relativistic level using an effective core potential (ECP) for Os, at the all-electron scalar exact two-component (X2C) relativistic level, and at the relativistic X2C level including spin-orbit coupling (SO-X2C). In earlier studies, the osmapentalene (1) and the osmapentalynes (2 and 3) were considered Craig-type Möbius aromatic and it was suggested that the analogous osmium compound (4) is Craig-type Möbius antiaromatic. Here, the ring-current strengths were obtained with the gauge including magnetically induced currents (GIMIC) method by integrating the MICD susceptibility passing through planes that intersect chemical bonds and by line integration of the induced magnetic field using Ampère-Maxwell's law. The ring-current calculations suggest that 1, 2 and 3 are weakly aromatic and that 4 is nonaromatic. The accuracy of the MICD susceptibility was assessed by comparing calculated NMR chemical shifts to available experimental data. Visualization of the MICD susceptibility shows that the ring current does not pass from one side of the molecular plane to the other, which means that the MICD susceptibility of the studied molecules does not exhibit any Möbius topology as one would expect for Craig-type Möbius aromatic and for Craig-type Möbius antiaromatic molecules. Thus, molecules 1-3 are not Craig-type Möbius aromatic and molecule 4 is not Craig-type Möbius antiaromatic as previously suggested. Calculations of the 1H NMR and 13C NMR chemical shifts of atoms near the Os atom show the importance of including spin-orbit effects. Overall, our study revisits the understanding of the aromaticity of organometallic molecules containing transition metals.
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Affiliation(s)
- Antonia Rabe
- Department Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, 55128 Mainz, Germany.
- Department of Chemistry, Faculty of Science, University of Helsinki, P. O. Box 55 (A. I. Virtasen aukio 1), FIN-00014, Helsinki, Finland.
| | - Qian Wang
- Department of Chemistry, Faculty of Science, University of Helsinki, P. O. Box 55 (A. I. Virtasen aukio 1), FIN-00014, Helsinki, Finland.
| | - Dage Sundholm
- Department of Chemistry, Faculty of Science, University of Helsinki, P. O. Box 55 (A. I. Virtasen aukio 1), FIN-00014, Helsinki, Finland.
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2
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Blasco D, Sundholm D. The aromatic nature of auracycles and diauracycles based on calculated ring-current strengths. Dalton Trans 2024; 53:10150-10158. [PMID: 38819195 DOI: 10.1039/d4dt00827h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
We have calculated the magnetically induced current density susceptibility for gold-containing organometallic molecular rings using the gauge-including magnetically induced currents (GIMIC) method. The aromatic nature has been determined by calculating the strength of the magnetically induced ring current susceptibility, which is often called ring current. To our knowledge, we show here for the first time that gold-containing organometallic rings may be aromatic or antiaromatic sustaining ring currents in the presence of an external magnetic field. The calculated aromatic character of the rings agrees with the aromatic nature one expects when using Hückel's aromaticity rules. The studied auracycles and diauracycles with 4n electrons in the conjugated orbitals generally sustain a weak paratropic ring current, whereas those having 4n + 2 electrons in the conjugated orbitals sustain a diatropic ring current that is almost as strong as that of benzene. The number of electrons are obtained by assuming that each C, N and Au atom of the ring contribute one electron, and a H atom connected to a N atom in the ring increases the number of electrons by one. An electron-attracting ligand at Au removes one electron from the ring. Formation of a short Au-Au bonding diauracycles reduces the number of electrons in the ring by two.
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Affiliation(s)
- Daniel Blasco
- Departamento de Química, Instituto de Investigación en Química (IQUR), Universidad de La Rioja, Madre de Dios 53, 26006, Logroño, Spain.
| | - Dage Sundholm
- Department of Chemistry, Faculty of Science, University of Helsinki, P. O. Box 55 (A. I. Virtasen aukio 1), FIN-00014, Helsinki, Finland.
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3
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Wolf S, Köppe R, Treptow J, Feuerstein W, Wenzel J, Breher F, Roesky PW, Weigend F, Klopper W, Feldmann C. [GeRu 6(CO) 18HI]: A Germanium-Centered Ruthenium Carbonyl Cluster with Aromatic Ring Current. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2309043. [PMID: 38509846 DOI: 10.1002/advs.202309043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 01/15/2024] [Indexed: 03/22/2024]
Abstract
The carbonyl cluster compound [GeRu6(CO)18HI] is unique in regard to its structure and bonding with a GeRu6 cluster core, a planar GeRu4HI unit, extensive multi-center bonding, and an aromatic ring current similar to benzene (9-10 nA T-1). The open-shell cluster core is a Ge-centered five-membered Ru4(Ru2) ring with CO ligands and an additional H and I atom, each bridging two Ru atoms on opposite sides of the cluster core. The compound is prepared at 130 °C in a weakly-coordinating ionic liquid.
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Affiliation(s)
- Silke Wolf
- Institute for Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstraße 15, D-76131, Karlsruhe, Germany
| | - Ralf Köppe
- Institute for Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstraße 15, D-76131, Karlsruhe, Germany
| | - Jens Treptow
- Institute for Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstraße 15, D-76131, Karlsruhe, Germany
| | - Wolfram Feuerstein
- Institute for Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstraße 15, D-76131, Karlsruhe, Germany
| | - Jonas Wenzel
- Institute for Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstraße 15, D-76131, Karlsruhe, Germany
| | - Frank Breher
- Institute for Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstraße 15, D-76131, Karlsruhe, Germany
| | - Peter W Roesky
- Institute for Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstraße 15, D-76131, Karlsruhe, Germany
| | - Florian Weigend
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, D-35043, Marburg, Germany
| | - Wim Klopper
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, D-76131, Karlsruhe, Germany
| | - Claus Feldmann
- Institute for Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstraße 15, D-76131, Karlsruhe, Germany
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4
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Lin X, Lu X, Tang S, Wu W, Mo Y. Multiconfigurational actinide nitrides assisted by double Möbius aromaticity. Chem Sci 2024; 15:8216-8226. [PMID: 38817572 PMCID: PMC11134321 DOI: 10.1039/d4sc01549e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 04/25/2024] [Indexed: 06/01/2024] Open
Abstract
Understanding the bonding nature between actinides and main-group elements remains a key challenge in actinide chemistry due to the involvement of f orbitals. Herein, we propose a unique "aromaticity-assisted multiconfiguration" (AAM) model to elucidate the bonding nature in actinide nitrides (An2N2, An = Ac, Th, Pa, U). Each planar four-membered An2N2 with equivalent An-N bonds possesses four delocalized π electrons and four delocalized σ electrons, forming a new family of double Möbius aromaticity that contributes to the molecular stability. The unprecedented aromaticity further supports actinide nitrides to exhibit multiconfigurational characters, where the unpaired electrons (2, 4 or 6 in naked Th2N2, Pa2N2 or U2N2, respectively) either are spin-free and localized on metal centres or form metal-ligand bonds. High-level multiconfigurational computations confirm an open-shell singlet ground state for actinide nitrides, with small energy gaps to high spin states. This is consistent with the antiferromagnetic nature observed experimentally in uranium nitrides. The novel AAM bonding model can be authenticated in both experimentally identified compounds containing a U2N2 motif and other theoretically modelled An2N2 clusters and is thus expected to be a general chemical bonding pattern between actinides and main-group elements.
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Affiliation(s)
- Xuhui Lin
- School of Physics, Central South University Changsha Hunan 410083 China
| | - Xiaoli Lu
- School of Chemistry, Southwest Jiaotong University Chengdu Sichuan 610031 China
| | - Shenghui Tang
- School of Chemistry, Southwest Jiaotong University Chengdu Sichuan 610031 China
| | - Wei Wu
- The State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and College of Chemistry and Chemical Engineering, Xiamen University Xiamen Fujian 361005 China
| | - Yirong Mo
- Department of Nanoscience, Joint School of Nanoscience and Nanoengineering, University of North Carolina at Greensboro Greensboro NC 27401 USA
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5
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Yang C, Dong H, Li X, Zhou N, Liu Y, Jin J, Wang Y. The σ+π dual aromaticity of typical bi-tetrazole ring molecule TKX-50. Chemphyschem 2024; 25:e202400005. [PMID: 38259129 DOI: 10.1002/cphc.202400005] [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: 01/02/2024] [Revised: 01/19/2024] [Accepted: 01/23/2024] [Indexed: 01/24/2024]
Abstract
Two complexes of dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50) were employed to evaluate the aromaticity of their tetrazole rings via deep analysis such as the electronic structure, the ZZ component of the natural chemical shielding tensor (NICSZZ) and component orbitals, localized orbital locator purely contributed by σ-orbitals (LOL-σ) and localized orbital locator purely contributed by π-orbitals (LOL-π), the anisotropy of the induced current density (AICD) and the ZZ component of iso-chemical shielding surface (ICSSZZ) of these tetrazole rings thereof. The conclusion shows: that all tetrazole rings and bi-tetrazole rings in complexes have strong σ and a comparable strength π double aromaticity; all these magnetic shields almost symmetrically increase from the central axis to the tetrazole ring atoms; tetrazole rings in complex II show a little stronger dual aromaticity than that in complex I mainly due to the different orientation of the fragment 2 encompassing two hydroxylamine groups resulting in different effects on the contributions of σ orbitals and π orbitals to total aromaticity of tetrazole rings thereof; the difference in aromaticity is fundamentally caused by the atoms O with stronger electron-withdrawing than atom N in fragment 2 interact with bi-tetrazole ring through O in complex I but through N in complex II.
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Affiliation(s)
- Chunhai Yang
- School of Materials Engineering, Changshu Institute of Technology, Suzhou, 215500, China
| | - Huilong Dong
- School of Materials Engineering, Changshu Institute of Technology, Suzhou, 215500, China
| | - Xue Li
- School of Petroleum Engineering, Changzhou University, Changzhou, 213164, China
| | - Ning Zhou
- School of Petroleum Engineering, Changzhou University, Changzhou, 213164, China
| | - Yi Liu
- College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao, 266580, China
| | - Junxun Jin
- School of Materials Engineering, Changshu Institute of Technology, Suzhou, 215500, China
| | - Yinjun Wang
- BGRIMM Explosive & Blasting Technology Co., Ltd., Beijing, 100160, China
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6
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Dobrowolski JC, Ostrowski S. HOMA Index Establishes Similarity to a Reference Molecule. J Chem Inf Model 2023; 63:7744-7754. [PMID: 38055931 PMCID: PMC10751799 DOI: 10.1021/acs.jcim.3c01551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/24/2023] [Accepted: 11/27/2023] [Indexed: 12/08/2023]
Abstract
The article shows that the definition of the HOMA index of geometrical aromaticity satisfies the axioms of a similarity function between the examined and benzene ring. Consequently, for purely mathematical reasons, the index works exceptionally well as an index of aromaticity: it expresses a geometric similarity to the archetypal aromatic benzene. Thus, if the molecule is geometrically similar to benzene, then it is also chemically similar, and therefore, it is aromatic. However, the similarity property legitimizes using the HOMA-like indices to express similarity to molecules other than benzene, whether cyclic or linear and existing or hypothetical. The paper demonstrates an example of HOMA-similarity to cyclohexane, which expresses a (relaxed)-saturicity property not accompanied by strong structural strains or steric hindrances. Further, it is also shown that the HOMA index can evaluate the properties of whole molecules, such as 25 unbranched catacondensed isomers of hexacene. The index exhibits a significant quadratic correlation with the total energy differences of planar isomers from which the nonplanar ones deviate. Moreover, the HOMA index of hexacene isomers significantly correlates with the Kekulé count connected to the resonance energy in the Hückel approximation. As a result, the study shows that the HOMA index can be used not only for aromaticity analyses but also as a general chemical descriptor applicable to rings, chains, composed molecular moieties, or even whole molecules.
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Affiliation(s)
- Jan Cz. Dobrowolski
- Institute of Nuclear Chemistry
and Technology, 16 Dorodna Street, 03-195 Warsaw, Poland
| | - Sławomir Ostrowski
- Institute of Nuclear Chemistry
and Technology, 16 Dorodna Street, 03-195 Warsaw, Poland
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7
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Franzke YJ, Holzer C. Exact two-component theory becoming an efficient tool for NMR shieldings and shifts with spin-orbit coupling. J Chem Phys 2023; 159:184102. [PMID: 37937936 DOI: 10.1063/5.0171509] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 09/04/2023] [Indexed: 11/09/2023] Open
Abstract
We present a gauge-origin invariant exact two-component (X2C) approach within a modern density functional framework, supporting meta-generalized gradient approximations such as TPSS and range-separated hybrid functionals such as CAM-B3LYP. The complete exchange-correlation kernel is applied, including the direct contribution of the field-dependent basis functions and the reorthonormalization contribution from the perturbed overlap matrix. Additionally, the finite nucleus model is available for the electron-nucleus potential and the vector potential throughout. Efficiency is ensured by the diagonal local approximation to the unitary decoupling transformation in X2C as well as the (multipole-accelerated) resolution of the identity approximation for the Coulomb term (MARI-J, RI-J) and the seminumerical exchange approximation. Errors introduced by these approximations are assessed and found to be clearly negligible. The applicability of our implementation to large-scale calculations is demonstrated for a tin pincer-type system as well as low-valent tin and lead complexes. Here, the calculation of the Sn nuclear magnetic resonance shifts for the pincer-type ligand with about 2400 basis functions requires less than 1 h for hybrid density functionals. Further, the impact of spin-orbit coupling on the nucleus-independent chemical shifts and the corresponding ring currents of all-metal aromatic systems is studied.
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Affiliation(s)
- Yannick J Franzke
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
| | - Christof Holzer
- Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Straße 1, 76131 Karlsruhe, Germany
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8
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Jarończyk M, Ostrowski S, Dobrowolski JC. On Integral INICS Aromaticity of Pyridodiazepine Constitutional Isomers and Tautomers. Molecules 2023; 28:5684. [PMID: 37570653 PMCID: PMC10419959 DOI: 10.3390/molecules28155684] [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: 05/25/2023] [Revised: 07/24/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
The structure, energetics, and aromaticity of c.a. 100 constitutional isomers and tautomers of pyrido[m,n]diazepines (m = 1, 2; n = 2, 3, 4, 5; m ≠ n) were studied at the B3LYP/cc-pVTZ level. The pyrido[1,3]diazepines appear the most, while pyrido[2,4]diazepines are the least stable (ca. 26 kcal/mol). In the pyrido[1,n]diazepine group (n = 2-5), the [1,5] isomers are higher in energy by ca. 4.5 kcal/mol and the [1,4] ones by ca. 7 kcal/mol, and the pyrido[1,2]diazepines are the least stable (ca. 20 kcal/mol). All the most stable pyrido[1,n]diazepines have N-atoms near the ring's junction bond but on opposite sites. The most stable [2,n]-forms are also those with the pyridine ring N6-atom near the junction bond. Surprisingly, for the [1,2]-, [1,3]-, and [1,4]-isomer condensation types of pyridine and diazepine rings, the same N9 > N7 > N6 > N8 stability pattern obeys. The stability remains similar in a water medium simulated with the Polarizable Continuum Model of the solvent and is conserved when calculated using the CAM-B3LYP or BHandHlyp functionals. The ring's aromaticity in the pyridine[m,n]diazepines was established based on the integral INICS index resulting from the NICSzz-scan curves' integration. The integral INICS index is physically justified through its relation to the ringcurrent as demonstrated by Berger, R.J.F., et al. Phys. Chem. Chem. Phys. 2022, 24, 624. The six-membered pyrido rings have negative INICSZZ indices and can be aromatic only if they are not protonated at the N-atom. All protonated pyrido and seven-membered rings exhibit meaningful positive INICSZZ values and can be assigned as antiaromatic. However, some non-protonated pyrido rings also have substantial positive INICSZZ indices and are antiaromatic. A weak linear correlation (R2 = 0.72) between the INICSZZ values of the pyridine I(6) and diazepine I(7) rings exists and is a consequence of the communication between the π-electron systems of the two rings. The juxtaposition of the INICS descriptor of the six- and seven-membered rings and diverse electron density parameters at the Ring Critical Points (RCP) revealed good correlations only with the Electrostatic Potentials from the electrons and nuclei (ESPe and ESPn). The relationships with other RCP parameters like electron density and its Laplacian, total energy, and the Hamiltonian form of kinetic energy density were split into two parts: one nearly constant for the six-membered rings and one linearly correlating for the seven-membered rings. Thus, most of the electron density parameters at the RCP of the six-membered rings of pyridodiazepines practically do not change with the diazepine type and the labile proton position. In contrast, those of the seven-membered rings display aromaticity changes in the antiaromatic diazepine with its ring structural modifications.
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Affiliation(s)
| | - Sławomir Ostrowski
- Institute of Chemistry and Nuclear Technology, 16 Dorodna Street, 03-195 Warsaw, Poland;
| | - Jan Cz. Dobrowolski
- National Medicines Institute, 30/34 Chełmska Street, 00-725 Warsaw, Poland
- Institute of Chemistry and Nuclear Technology, 16 Dorodna Street, 03-195 Warsaw, Poland;
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9
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Merino G, Solà M, Fernández I, Foroutan-Nejad C, Lazzeretti P, Frenking G, Anderson HL, Sundholm D, Cossío FP, Petrukhina MA, Wu J, Wu JI, Restrepo A. Aromaticity: Quo Vadis. Chem Sci 2023; 14:5569-5576. [PMID: 37265727 PMCID: PMC10231312 DOI: 10.1039/d2sc04998h] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 02/22/2023] [Indexed: 07/25/2023] Open
Abstract
Aromaticity is one of the most deeply rooted concepts in chemistry. But why, if two-thirds of existing compounds can be classified as aromatic, is there no consensus on what aromaticity is? σ-, π-, δ-, spherical, Möbius, or all-metal aromaticity… why are so many attributes needed to specify a property? Is aromaticity a dubious concept? This perspective aims to reflect where the aromaticity community is and where it is going.
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Affiliation(s)
- 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 97310 Mérida Yucatán Mexico
| | - Miquel Solà
- Institut de Química Computacional i Catàlisi and Department de Química, Universitat de Girona C/M. Aurèlia Capmany, 69 Girona 17003 Catalonia Spain
| | - Israel Fernández
- Departamento de Química Orgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA), Facultad de Ciencias Químicas, Universidad Complutense de Madrid 28040 Madrid Spain
| | - Cina Foroutan-Nejad
- Institute of Organic Chemistry, Polish Academy of Sciences Kasprzaka 44/52 01-224 Warsaw Poland
| | - Paolo Lazzeretti
- Dipartimento di Chimica e Biologia "A. Zambelli", Università degli Studi di Salerno via Giovanni Paolo II 132, Fisciano 84084 SA Italy
| | - Gernot Frenking
- Fachbereich Chemie, Philipps-Universität Marburg Hans-Meerwein-Strasse 4, D-35043 Marburg Germany
| | | | - Dage Sundholm
- Department of Chemistry, Faculty of Science, University of Helsinki P.O. Box 55, A. I. Virtasen aukio 1 FIN-00014 Helsinki Finland
| | - Fernando P Cossío
- Departamento de Química Orgánica I, Instituto de Innovaciónen Química Avanzada (ORFEO-CINQA), University of the Basque Country (UPV/EHU) Paseo Manuel Lardizabal 3 20018 Donostia/San Sebastián Spain
| | - Marina A Petrukhina
- Department of Chemistry, University at Albany, State University of New York Albany New York 12222 USA
| | - Jishan Wu
- Department of Chemistry, National University of Singapore 3 Science Drive 3 Singapore 117543 Singapore
| | - Judy I Wu
- Department of Chemistry, University of Houston Houston Texas 77204 USA
| | - Albeiro Restrepo
- Instituto de Química, Universidad de Antioquia Calle 70 No. 52-21 050010 Medellín Colombia
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10
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Bradley D, Jirásek M, Anderson HL, Peeks MD. Disentangling global and local ring currents. Chem Sci 2023; 14:1762-1768. [PMID: 36819862 PMCID: PMC9930925 DOI: 10.1039/d2sc05923a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 01/13/2023] [Indexed: 01/18/2023] Open
Abstract
Magnetic field-induced ring currents in aromatic and antiaromatic molecules cause characteristic shielding and deshielding effects in the molecules' NMR spectra. However, it is difficult to analyze (anti)aromaticity directly from experimental NMR data if a molecule has multiple ring current pathways. Here we present a method for using the Biot-Savart law to deconvolute the contributions of different ring currents to the experimental NMR spectra of polycyclic compounds. This method accurately quantifies local and global ring current susceptibilities in porphyrin nanorings, as well as in a bicyclic dithienothiophene-bridged [34]octaphyrin. There is excellent agreement between ring current susceptibilities derived from both experimental and computationally-predicted chemical shifts, and with ring currents calculated by the GIMIC method. Our method can be applied to any polycyclic system, with any number of ring currents, provided that appropriate NMR data are available.
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Affiliation(s)
- David Bradley
- School of Chemistry, University of New South Wales Sydney NSW 2052 Australia
| | | | | | - Martin D. Peeks
- School of Chemistry, University of New South WalesSydneyNSW 2052Australia
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11
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Macleod-Carey D, Muñoz-Castro A. Switch from local to global aromatic character in Möbius carbon nanobelts upon dioxidation. Evaluation of magnetic behavior in neutral and charged species. Phys Chem Chem Phys 2023; 25:4467-4471. [PMID: 36722854 DOI: 10.1039/d2cp05326h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Here we show that recent Möbius carbon nanobelts (MCNBs) can be switched from a local to a global aromatic behavior upon dioxidation. Hence, large aromatic structures can be achieved by the choice of the charge states, giving rise to shielding cone characteristics extended within the overall structure at the nanoscale regime, pushing the limit of aromatic circuits to 198 π-electrons.
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Affiliation(s)
- Desmond Macleod-Carey
- Laboratorio de Química Inorgánica y Materiales Moleculares, Facultad de Ingenieria, Universidad Autonoma de Chile, Llano Subercaceaux 2801, San Miguel, Santiago, Chile
| | - Alvaro Muñoz-Castro
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Bellavista 7, Santiago, 8420524, Chile.
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12
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Bai LX, Orozco-Ic M, Zarate X, Sundholm D, Pan S, Guo JC, Merino G. B 3Al 4+: A Three-Dimensional Molecular Reuleaux Triangle. Molecules 2022; 27:7407. [PMID: 36364234 PMCID: PMC9656129 DOI: 10.3390/molecules27217407] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/19/2022] [Accepted: 10/23/2022] [Indexed: 12/02/2023] Open
Abstract
We systematically explore the potential energy surface of the B3Al4+ combination of atoms. The putative global minimum corresponds to a structure formed by an Al4 square facing a B3 triangle. Interestingly, the dynamical behavior can be described as a Reuleaux molecular triangle since it involves the rotation of the B3 triangle at the top of the Al4 square. The molecular dynamics simulations, corroborating with the very small rotational barriers of the B3 triangle, show its nearly free rotation on the Al4 ring, confirming the fluxional character of the cluster. Moreover, while the chemical bonding analysis suggests that the multicenter interaction between the two fragments determines its fluxionality, the magnetic response analysis reveals this cluster as a true and fully three-dimensional aromatic system.
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Affiliation(s)
- Li-Xia Bai
- Nanocluster Laboratory, Institute of Molecular Science, Shanxi University, Taiyuan 030006, China
| | - Mesías Orozco-Ic
- Department of Chemistry, University of Helsinki, A. I. Virtasen Aukio 1, P.O. Box 55, FIN-00014 Helsinki, Finland
| | - Ximena Zarate
- Instituto de Ciencias Químicas Aplicadas, Facultad de Ingeniería, Universidad Autónoma de Chile, Av. Pedro de Valdivia 425, Santiago 7500912, Chile
| | - Dage Sundholm
- Department of Chemistry, University of Helsinki, A. I. Virtasen Aukio 1, P.O. Box 55, FIN-00014 Helsinki, Finland
| | - Sudip Pan
- Fachbereich Chemie, Philipps-Universitt Marburg Hans-Meerwein-Straße, 35043 Marburg, Germany
| | - Jin-Chang Guo
- Nanocluster Laboratory, Institute of Molecular Science, Shanxi University, Taiyuan 030006, China
| | - 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, Merida 97310, Mexico
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13
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Landi A, Summa FF, Zanasi R, Monaco G. On the JAP Method for the Indirect Determination of Delocalized Currents from Experimental Chemical Shifts. Chemphyschem 2022; 23:e202200411. [PMID: 35811448 PMCID: PMC9796333 DOI: 10.1002/cphc.202200411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/02/2022] [Indexed: 01/01/2023]
Abstract
The JAP model (after Jirásek, Anderson, and Peeks) to retrieve global current strengths from experimental 1 H chemical shifts has been tested with DFT computations. Both global and local tropicities are correctly predicted in most cases and the quantitative agreement is overall fair. An extension of the model is found to give improvement in an exemplary critical case, where the global delocalized current is negligible and the current density map is dominated by local currents.
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Affiliation(s)
- Alessandro Landi
- Department of Chemistry and Biology “A. Zambelli”Università di SalernoVia G. Paolo II, 132Fisciano84084 SAItaly
| | - Francesco F. Summa
- Department of Chemistry and Biology “A. Zambelli”Università di SalernoVia G. Paolo II, 132Fisciano84084 SAItaly
| | - Riccardo Zanasi
- Department of Chemistry and Biology “A. Zambelli”Università di SalernoVia G. Paolo II, 132Fisciano84084 SAItaly
| | - Guglielmo Monaco
- Department of Chemistry and Biology “A. Zambelli”Università di SalernoVia G. Paolo II, 132Fisciano84084 SAItaly
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14
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Berger RJF, Dimitrova M. A natural scheme for the quantitative analysis of the magnetically induced molecular current density using an oriented flux-weighted stagnation graph. I. A minimal example for LiH. Phys Chem Chem Phys 2022; 24:23089-23095. [PMID: 36129405 DOI: 10.1039/d2cp02262a] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new natural scheme is introduced to analyze quantitatively the magnetically induced molecular current density vector field, J. The set of zero points of J, which is called its stagnation graph (SG), has been previously used to study the topological features of the current density of various molecules. Here, the line integrals of the induced magnetic field along edges of the connected subset of the SG are calculated. The edges are oriented such that all weights, i.e., flux values become non-negative, thereby, an oriented flux-weighted (current density) stagnation graph (OFW-SG) is obtained. Since in the exact theoretical limit, J is divergence-free and due to the topological characteristics of such vector fields, the flux of all separate vortices (current density domains) and neighbouring connected vortices can be determined exactly by adding the weights of cyclic subsets of edges (i.e., closed loops) of the OFW-SG. The procedure is exemplified by the minimal example of LiH for a weak homogeneous external magnetic field, B, perpendicular to the chemical bond. The OFW-SG exhibits one closed loop (formally decomposed into two edges), and an open line extending to infinity on both of its ends. The method provides the means of accurately determining the strength of the current density even in molecules with a complicated set of distinct vortices.
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Affiliation(s)
- Raphael J F Berger
- Fachbereich für Chemie und Physik der Materialien, Paris-Lodron Universität Salzburg, Jakob-Harringerstr. 2a, A-5020 Salzburg, Österreich, Austria.
| | - Maria Dimitrova
- Department of Chemistry, Faculty of Science, University of Helsinki, P.O. Box 55, A. I. Virtasen aukio 1, FI-00014, Finland
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15
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Franzke YJ, Holzer C. Communication: Impact of the current density on paramagnetic NMR properties. J Chem Phys 2022; 157:031102. [DOI: 10.1063/5.0103898] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Meta-generalized gradient approximations (meta-GGAs) and local hybrid functionals generally depend on the kinetic energy density τ. For magnetic properties, this necessitates generalizations to ensure gauge invariance. In most implementations, τ is generalized by incorporating the external magnetic field. However, this introduces artifacts in the response of the density matrix and does not satisfy the iso-orbital constraint. Here, we extend previous approaches based on the current density to paramagnetic NMR shieldings and EPR g-tensors. The impact is assessed for main-group compounds and transition-metal complexes considering 25 density functional approximations. It is shown that the current density leads to substantial improvements-especially for the popular Minnesota and SCAN functional families. Thus, we strongly recommend to use the current density generalized τ in paramagnetic NMR and EPR calculations with meta-GGAs.
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Affiliation(s)
- Yannick J. Franzke
- Fachbereich Chemie, Philipps-Universität Marburg Fachbereich Chemie, Germany
| | - Christof Holzer
- Institute of Theoretical Solid State Physics, Karlsruher Institut für Technologie Fakultät für Physik, Germany
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16
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Baryshnikov GV, Valiev RR, Valiulina LI, Kurtsevich AE, Kurtén T, Sundholm D, Pittelkow M, Zhang J, Ågren H. Odd-Number Cyclo[ n]Carbons Sustaining Alternating Aromaticity. J Phys Chem A 2022; 126:2445-2452. [PMID: 35420813 PMCID: PMC9059118 DOI: 10.1021/acs.jpca.1c08507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Cyclo[n]carbons (n = 5, 7, 9,
..., 29) composed from an odd number of carbon atoms are studied computationally
at density functional theory (DFT) and ab initio complete
active space self-consistent field (CASSCF) levels of theory to get
insight into their electronic structure and aromaticity. DFT calculations
predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In
contrast, calculations at the CASSCF level yield geometrically bent
and electronically localized carbene structures leading to an alternating
double aromaticity of the odd-number cyclo[n]carbons.
CASSCF calculations yield a singlet electronic ground state for the
studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest
singlet and triplet states depends on the employed functional. The
BHandHLYP functional predicts a triplet ground state of the larger
odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level
using the CASSCF-optimized molecular structures show that there is
a through-space delocalization in the cyclo[n]carbons.
The current density avoids the carbene carbon atom, leading to an
alternating double aromaticity of the odd-number cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules.
C11, C15, and C19 are aromatic and
can be prioritized in future synthesis. We predict a bond-shift phenomenon
for the triplet state of the cyclo[n]carbons leading
to resonance structures that have different reactivity toward dimerization.
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Affiliation(s)
- Glib V Baryshnikov
- College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, Henan, P. R. China.,Laboratory of Organic Electronics, Department of Science and Technology, Linköping University, Norrköping SE-60174, Sweden
| | - Rashid R Valiev
- Department of Chemistry, Faculty of Science, University of Helsinki, FIN-00014 Helsinki, Finland
| | - Lenara I Valiulina
- Department of Optics and Spectroscopy, Tomsk State University, Tomsk 634050, Russia
| | | | - Theo Kurtén
- Department of Chemistry, Faculty of Science, University of Helsinki, FIN-00014 Helsinki, Finland
| | - Dage Sundholm
- Department of Chemistry, Faculty of Science, University of Helsinki, FIN-00014 Helsinki, Finland
| | - Michael Pittelkow
- Department of Chemistry, University of Copenhagen, Copenhagen Ø DK-2100, Denmark
| | - Jinglai Zhang
- College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, Henan, P. R. China
| | - Hans Ågren
- College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, Henan, P. R. China.,Department of Physics and Astronomy, Uppsala University, Uppsala SE-75120, Sweden
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17
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Paenurk E, Gershoni-Poranne R. Simple and efficient visualization of aromaticity: bond currents calculated from NICS values. Phys Chem Chem Phys 2022; 24:8631-8644. [PMID: 35132428 DOI: 10.1039/d1cp05757j] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Aromaticity is a fundamental concept in chemistry, underpinning the properties and reactivity of many organic compounds and materials. The ability to easily and accurately discern aromatic behavior is key to leveraging it as a design element, yet most aromaticity metrics struggle to combine accurate quantitative evaluation, intuitive interpretability, and user-friendliness. We introduce a new method, NICS2BC, which uses simple and inexpensive NICS calculations to generate information-rich and easily-interpreted bond-current graphs. We test the quantitative and qualitative characterizations afforded by NICS2BC for a selection of molecules of varying structural and electronic complexity, to demonstrate its accuracy and ease of analysis. Moreover, we show that NICS2BC successfully identifies ring-current patterns in molecules known to be difficult cases to interpret with NICS and enables deeper understanding of local aromaticity trends, demonstrating that our method adds additional insight.
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Affiliation(s)
- Eno Paenurk
- Laboratorium für Organische Chemie, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093 Zürich, Switzerland
| | - Renana Gershoni-Poranne
- Laboratorium für Organische Chemie, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093 Zürich, Switzerland.,Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa 32000, Israel.
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18
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Gu X, Yang L, Jin P. Planar Inorganic Five-Membered Heterocycles with σ+π Dual Aromaticity in Both S0 and T1 States. Phys Chem Chem Phys 2022; 24:22091-22101. [DOI: 10.1039/d2cp03116g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cyclic species being aromatic in both the lowest singlet and triplet electronic states (so-called adaptive aromaticity) are scarce. To date, the reported systems are mostly organometallic heterocycles with the aromaticities...
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