1
|
Rossi C, Gans B, Giuliani A, Jacovella U. Vacuum Ultraviolet Fingerprints as a New Way of Disentangling Tropylium/Benzylium Isomers. J Phys Chem Lett 2023; 14:8444-8447. [PMID: 37713678 DOI: 10.1021/acs.jpclett.3c01973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/17/2023]
Abstract
The two inseparable companions, tropylium (Tr+) and benzylium (Bz+), were interrogated by vacuum ultraviolet (VUV) radiation from 4.5 to 7.0 eV in an ion trap. These new fingerprints provide a new means of distinguishing these two intertwined C7H7+ isomers. In particular, the singular spectral signature of Tr+ in the VUV consists of a single strong electronic transition at ≈6 eV. To illustrate this diagnostic tool, we shed light on the structure of the C7H7+ intermediate that is ubiquitous when using commercial atmospheric pressure photoionization (APPI) sources. We have identified its structure as the 7-membered ring Tr+, which contradicts some previous beliefs.
Collapse
Affiliation(s)
- Corentin Rossi
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405 Orsay, France
| | - Bérenger Gans
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405 Orsay, France
| | - Alexandre Giuliani
- Synchrotron SOLEIL, L'Orme des Merisiers, 91192 Saint Aubin, Gif-sur-Yvette, France
- INRAE, UAR1008, Transform Department, Rue de la Géraudiére, BP 71627, 44316 Nantes, France
| | - Ugo Jacovella
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405 Orsay, France
| |
Collapse
|
2
|
Zahra FT, Saeed A, Mumtaz K, Albericio F. Tropylium Ion, an Intriguing Moiety in Organic Chemistry. Molecules 2023; 28:molecules28104095. [PMID: 37241836 DOI: 10.3390/molecules28104095] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 05/06/2023] [Accepted: 05/11/2023] [Indexed: 05/28/2023] Open
Abstract
The tropylium ion is a non-benzenoid aromatic species that works as a catalyst. This chemical entity brings about a large number of organic transformations, such as hydroboration reactions, ring contraction, the trapping of enolates, oxidative functionalization, metathesis, insertion, acetalization, and trans-acetalization reactions. The tropylium ion also functions as a coupling reagent in synthetic reactions. This cation's versatility can be seen in its role in the synthesis of macrocyclic compounds and cage structures. Bearing a charge, the tropylium ion is more prone to nucleophilic/electrophilic reactions than neutral benzenoid equivalents. This ability enables it to assist in a variety of chemical reactions. The primary purpose of using tropylium ions in organic reactions is to replace transition metals in catalysis chemistry. It outperforms transition-metal catalysts in terms of its yield, moderate conditions, non-toxic byproducts, functional group tolerance, selectivity, and ease of handling. Furthermore, the tropylium ion is simple to synthesize in the laboratory. The current review incorporates the literature reported from 1950 to 2021; however, the last two decades have witnessed a phenomenal upsurge in the utilization of the tropylium ion in the facilitation of organic conversions. The importance of the tropylium ion as an environmentally safe catalyst in synthesis and a comprehensive summary of some important reactions catalyzed via tropylium cations are described.
Collapse
Affiliation(s)
- Fatima Tuz Zahra
- Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan
| | - Aamer Saeed
- Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan
| | - Khansa Mumtaz
- Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan
| | - Fernando Albericio
- School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4001, South Africa
- CIBER-BBN, Networking Centre on Bioengineering, Biomaterials and Nanomedicine, Department of Organic Chemistry, University of Barcelona, 08028 Barcelona, Spain
| |
Collapse
|
3
|
Jacovella U, Scholz MS, Bieske EJ. Electronic Spectrum of the Tropylium Cation in the Gas Phase. J Phys Chem Lett 2020; 11:8867-8872. [PMID: 32990444 DOI: 10.1021/acs.jpclett.0c02430] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The structure and properties of the tropylium cation (C7H7+) have enthralled chemists since the prediction by Hückel in 1931 of the remarkable stability for cyclic, aromatic molecules containing six π-electrons. However, probing and understanding the excited electronic states of the isolated tropylium cation have proved challenging, as the accessible electronic transitions are weak, and there are difficulties in creating appreciable populations of the tropylium cation in the gas phase. Here, we present the first gas-phase S1 ←S0 electronic spectrum of the tropylium cation, recorded by resonance-enhanced photodissociation of weakly bound tropylium-Ar complexes. We demonstrate that the intensity of the symmetry-forbidden S1 ←S0 transition arises from Herzberg-Teller vibronic coupling between the S1 and S2 electronic states mediated by vibrational modes of e2' and e3' symmetry. The main geometry change upon excitation involves elongation of the C-C bonds. Multiconfigurational ab initio calculations predict that the S1 excited state is affected by the dynamical Jahn-Teller effect, which should lead to the appearance of additional weak bands that may be apparent in higher-resolution electronic spectra.
Collapse
Affiliation(s)
- Ugo Jacovella
- School of Chemistry, The University of Melbourne, Victoria 3010, Australia
| | - Michael S Scholz
- School of Chemistry, The University of Melbourne, Victoria 3010, Australia
| | - Evan J Bieske
- School of Chemistry, The University of Melbourne, Victoria 3010, Australia
| |
Collapse
|
4
|
Jacovella U, da Silva G, Bieske EJ. Unveiling New Isomers and Rearrangement Routes on the C 7H 8+ Potential Energy Surface. J Phys Chem A 2019; 123:823-830. [PMID: 30608153 DOI: 10.1021/acs.jpca.8b10642] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The unimolecular reactions of C7H8+ radical cations are among those most studied by mass spectrometry, especially the rearrangement of toluene and cycloheptatriene molecular ions, which are directly connected to the formation of benzylium and tropylium cations. This study reveals important new isomers and isomerization pathways on the C7H8+ potential energy surface, through the application of gas-phase electronic photodissociation spectroscopy in conjunction with ab initio calculations. Presented are the first gas-phase vibrationally resolved electronic spectra of the o-isotoluene, norcaradiene, bicyclo[3.2.0]hepta-2,6-diene radical cations, and ring-opened products from cyclic C7H8+ species. The isomerization route from the norbornadiene radical cation to the toluene radical cation, which competes with isomerization to the bicyclo[2.2.1]hepta-2-ene-5-yl-7-ylium radical cation, is identified. Further, this work expands understanding of the C7H8+ potential energy surface by connecting spiro[2.4]hepta-4,6-diene and acyclic 1,2,4,6-heptatetraene radical cations, and confirms the important role of the o-isotoluene radical cation in the interconversion pathways of C7H8+ species.
Collapse
Affiliation(s)
- Ugo Jacovella
- School of Chemistry , The University of Melbourne , Victoria 3010 , Australia
| | - Gabriel da Silva
- Department of Chemical Engineering , The University of Melbourne , Victoria 3010 , Australia
| | - Evan J Bieske
- School of Chemistry , The University of Melbourne , Victoria 3010 , Australia
| |
Collapse
|
5
|
Jusko P, Simon A, Banhatti S, Brünken S, Joblin C. Direct Evidence of the Benzylium and Tropylium Cations as the Two Long-Lived Isomers of C 7 H 7. Chemphyschem 2018; 19:3182-3185. [PMID: 30238585 PMCID: PMC6420061 DOI: 10.1002/cphc.201800744] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Indexed: 11/12/2022]
Abstract
Disentangling the isomeric structure of C7 H7 + is a longstanding experimental issue. We report here the full mid-infrared vibrational spectrum of C7 H7 + tagged with Ne obtained with infrared-predissociation spectroscopy at 10 K. Saturation depletion measurements were used to assign the contribution of benzylium and tropylium isomers and demonstrate that no other isomer is involved. Recorded spectral features compare well with density functional theory calculations. This opens perspectives for a better understanding and control of the formation paths leading to either tropylium or benzylium ions.
Collapse
Affiliation(s)
- Pavol Jusko
- Institut de Recherche en Astrophysique et Planétologie (IRAP), Université de Toulouse (UPS), CNRS, CNES, 9 Av. du Colonel Roche, 31028 Toulouse Cedex 4, France
| | - Aude Simon
- Laboratoire de Chimie et Physique Quantiques LCPQ/IRSAMC, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, 31062 Toulouse, France
| | - Shreyak Banhatti
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
| | - Sandra Brünken
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7c, 6525 ED, Nijmegen, The Netherlands
| | - Christine Joblin
- Institut de Recherche en Astrophysique et Planétologie (IRAP), Université de Toulouse (UPS), CNRS, CNES, 9 Av. du Colonel Roche, 31028 Toulouse Cedex 4, France
| |
Collapse
|
6
|
Paracelus Prize: B. Giese Werner Prize: N. CrameRužička Prize: R. Gilmour / Erwin Schrödinger Gold Medal: J. P. Maier. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/anie.201202172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
7
|
Paracelus-Preis: B. Giese Werner-Preis: N. Cramer Ružička-Preis: R. Gilmour Erwin-Schrödinger-Goldmedaille: J. P. Maier. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201202172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
8
|
Chiavarino B, Crestoni ME, Dopfer O, Maitre P, Fornarini S. Benzylium versus Tropylium Ion Dichotomy: Vibrational Spectroscopy of Gaseous C8H9+ Ions. Angew Chem Int Ed Engl 2012; 51:4947-9. [DOI: 10.1002/anie.201200558] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Indexed: 11/08/2022]
|
9
|
Chiavarino B, Crestoni ME, Dopfer O, Maitre P, Fornarini S. Benzylium versus Tropylium Ion Dichotomy: Vibrational Spectroscopy of Gaseous C8H9+ Ions. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201200558] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|