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Liu Q, Onishi K, Miyazawa Y, Wang Z, Hatano S, Abe M. Energetically More Stable Singlet Cyclopentane-1,3-diyl Diradical with π-Single Bonding Character than the Corresponding σ-Single Bonded Compound. J Am Chem Soc 2023. [PMID: 37967336 DOI: 10.1021/jacs.3c10971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2023]
Abstract
Carbon-carbon σ-single bonds are crucial for constructing molecules like ethane derivatives (R3C-CR3), which are composed of tetrahedral four-coordinate carbons. Molecular functions, such as light absorption or emission, originate from the π-bonds existing in ethylene derivatives (R2C═CR2). In this study, a relatively stable cyclopentane-1,3-diyl species with π-single bonding system (C-π-C) with planar four-coordinate carbons is constructed. This diradicaloid is energetically more stable than the corresponding σ-single bonding system. The π-electron single bonding system provides deeper insights into the chemical bonding and the physical properties derived from the small energy gaps between the bonding and antibonding molecular orbitals.
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Affiliation(s)
- Qian Liu
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
| | - Keita Onishi
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
| | - Yuki Miyazawa
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
| | - Zhe Wang
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
| | - Sayaka Hatano
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
| | - Manabu Abe
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
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Wang Z, Yadav P, Abe M. Long-lived localised singlet diradicaloids with carbon-carbon π-single bonding (C-π-C). Chem Commun (Camb) 2021; 57:11301-11309. [PMID: 34633003 DOI: 10.1039/d1cc04581d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Localised singlet cyclopentane-1,3-diyl diradicaloids have been considered promising candidates for constructing carbon-carbon π-single bonds (C-π-C). However, the high reactivity during formation of the σ-bond has limited a deeper investigation of its unique chemical properties. In this feature article, recent progress in kinetic stabilisation based on the "stretch effect" and the "solvent dynamic effect" induced by the macrocyclic system is summarised. Singlet diradicaloids S-DR4a/b and S-DR4d containing macrocyclic rings showed much longer lifetimes at 293 K (14 μs for S-DR4a and 156 μs for S-DR4b in benzene) compared to the parent singlet diradicaloid S-DR2 having no macrocyclic ring (209 ns in benzene). Furthermore, the dynamic solvent effect in viscous solvents was observed for the first time in intramolecular σ-bond formation, the lifetime of S-DR4d increased to 400 μs in the viscous solvent glycerin triacetin at 293 K. The experimental results proved the validity of the "stretch effect" and the "solvent dynamic effect" on the kinetic stabilisation of singlet cyclopentane-1,3-diyl diradicaloids, and provided a strategy for isolating the carbon-carbon π-single bonded species (C-π-C), and towards a deeper understanding of the nature of chemical bonding.
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Affiliation(s)
- Zhe Wang
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
| | - Pinky Yadav
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
| | - Manabu Abe
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
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Sarkar SK, Abe M. Direct Detection of Singlet Cyclopentane-1,3-diyl Diradicals By Infrared and Ultraviolet-Visible Spectroscopy at Cryogenic Temperature and Their Photoreactivity. J Org Chem 2021; 86:12046-12053. [PMID: 34380315 DOI: 10.1021/acs.joc.1c01410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photolysis of a 7,7-difluoro-1,4-diphenyl-2,3-diazabicyclo[2.2.1]hept-2-ene derivative (AZ1) using a 365 nm light-emitting diode in an Ar matrix at 4 K resulted in the formation of a planar singlet 2,2-difluoro-1,3-diphenylcyclopentane-1,3-diyl diradical derivative, S-DR1-pl (λmax = 520 nm). A singlet cyclopentane-1,3-diyl diradical system (S-DR1-pl) was directly detected by steady-state infrared (IR) spectroscopy. Due to the photolability of S-DR1-pl, initial photolysis of AZ1 also yielded the ring-closed product ret-CP1 and migration products trans-MG1 and/or cis-MG1, which were observed using IR spectra. Monitoring of prolonged photolysis using IR and ultraviolet-visible (UV-vis) spectra demonstrated the formation of the allylic cation CT1 (λmax = 470 nm). On the other hand, photolysis of a 7,7-dimethoxy-1,4-diphenyl-2,3-diazabicyclo[2.2.1]hept-2-ene derivative (AZ2) yielded a puckered conformer (instead of planar) of the corresponding diradical S-DR2-puc, which was detected by IR and UV-vis spectroscopy in an Ar matrix at 4 K. This spectroscopic characterization opens a new strategy to obtain more detailed information about the structure and reactivity of singlet cyclopentane-1,3-diyl diradicals.
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Affiliation(s)
- Sujan K Sarkar
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Manabu Abe
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.,Hiroshima University Research Center for Photo-Drug-Delivery Systems (HiU-P-DDS), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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Akisaka R, Abe M. Bulky Substituent Effect on Reactivity of Localized Singlet Cyclopentane‐1,3‐diyls with π‐Single Bonding (C‐π‐C) Character. Chem Asian J 2019; 14:4223-4228. [DOI: 10.1002/asia.201901253] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 10/01/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Rikuo Akisaka
- Department of ChemistryGraduate School of ScieneceHiroshima University 1-3-1 Kagamiyama, Higashi-Hiroshima Hiroshima 739-8526 Japan
| | - Manabu Abe
- Department of ChemistryGraduate School of ScieneceHiroshima University 1-3-1 Kagamiyama, Higashi-Hiroshima Hiroshima 739-8526 Japan
- Hiroshima UniversityResearch Center for Photo-Drug-Delivery System (HiU-P-DDS) 1-3-1 Kagamiyama, Higashi-Hiroshima Hiroshima 739-8526 Japan
- JST-CREST K's Gobancho 6F, 7, Gobancho, Chiyoda-ku Tokyo 102-0075 Japan
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Abe M. Generation of Extremely Long-lived Localized Singlet Diradicals: New Insights into Bond-homolysis Process and Discovery of Novel Bonding System (C-π-C). J SYN ORG CHEM JPN 2019. [DOI: 10.5059/yukigoseikyokaishi.77.503] [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]
Affiliation(s)
- Manabu Abe
- Department of Chemistry, Graduate School of Science, Hiroshima University
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Yoshidomi S, Abe M. 1,2-Diazacyclopentane-3,5-diyl Diradicals: Electronic Structure and Reactivity. J Am Chem Soc 2019; 141:3920-3933. [DOI: 10.1021/jacs.8b12254] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Manabu Abe
- JST-CREST, K’s Gobancho 6F, 7, Gobancho, Chiyoda-ku, Tokyo 102-0075, Japan
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Harada Y, Wang Z, Kumashiro S, Hatano S, Abe M. Extremely Long Lived Localized Singlet Diradicals in a Macrocyclic Structure: A Case Study on the Stretch Effect. Chemistry 2018; 24:14808-14815. [DOI: 10.1002/chem.201803076] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Revised: 07/14/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Yuta Harada
- Department of Chemistry; Graduate School of Science; Hiroshima University; 1-3-1 Kagamiyama Higashi-Hiroshima, Hiroshima 739-8526 Japan
| | - Zhe Wang
- Department of Chemistry; Graduate School of Science; Hiroshima University; 1-3-1 Kagamiyama Higashi-Hiroshima, Hiroshima 739-8526 Japan
| | - Shunsuke Kumashiro
- Department of Chemistry; Graduate School of Science; Hiroshima University; 1-3-1 Kagamiyama Higashi-Hiroshima, Hiroshima 739-8526 Japan
| | - Sayaka Hatano
- Department of Chemistry; Graduate School of Science; Hiroshima University; 1-3-1 Kagamiyama Higashi-Hiroshima, Hiroshima 739-8526 Japan
| | - Manabu Abe
- Department of Chemistry; Graduate School of Science; Hiroshima University; 1-3-1 Kagamiyama Higashi-Hiroshima, Hiroshima 739-8526 Japan
- Hiroshima University Research Center for, Photo-Drug-Delivery Systems (HiU-P-DDS); 1-3-1 Kagamiyama Higashi-Hiroshima, Hiroshima 739-8526 Japan
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Abe M, Kanahara K, Kadowaki N, Tan CJ, Tsai HHG. Unusually Long-Wavelength Emissions of Cyclopropanes: New Insight into C-C Bond Homolysis. Chemistry 2018; 24:7595-7600. [PMID: 29573002 DOI: 10.1002/chem.201800671] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Indexed: 11/07/2022]
Abstract
Bond homolysis (BHo) is a fundamental concept in chemical-bonding phenomena. To date, research studies on the BHo concept have provided crucial information for understanding the nature of chemical bonding and reactions. Two potential-energy minima, a σ-bonding isomer and a singlet-diradical isomer, have been known to exist in carbon-carbon BHo. Herein, a third isomer, that is, a puckered singlet diradical exhibiting unstructured long-wavelength fluorescence beyond 460 nm, was first observed in the excited states of 1,4-diarylbicyclo[2.1.0]pentane derivatives. The careful selection of appropriate substituents in the bicyclic structures enabled direct spectral detection. State-of-the-art ab initio quantum chemical calculations quantitatively reproduced the experimental observations. This new finding provides new insight into carbon-carbon bond-breaking and -forming processes.
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Affiliation(s)
- Manabu Abe
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526, Japan.,Hiroshima University Research Center for, Photo-Drug-Delivery Systems (HiU-P-DDS), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Kousei Kanahara
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Norito Kadowaki
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Chun-Jui Tan
- Department of Chemistry, National Central University, No. 300, Zhongda Road, Zhongli District, Taoyuan City, 32001, Taiwan
| | - Hui-Hsu Gavin Tsai
- Department of Chemistry, National Central University, No. 300, Zhongda Road, Zhongli District, Taoyuan City, 32001, Taiwan
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9
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Abe M, Akisaka R. Is π-Single Bonding (C–π–C) Possible? A Challenge in Organic Chemistry. CHEM LETT 2017. [DOI: 10.1246/cl.170711] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Manabu Abe
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526
- Hiroshima Research Center for Photo-Drug-Delivery Systems (Hi-P-DDS), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526
| | - Rikuo Akisaka
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526
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Abstract
Abstract
Since 1965, the stereoselectivity in azoalkane denitrogenation has attracted much attention in both synthetic organic chemistry and physical organic chemistry. In this paper, a short review of the recent findings on the mechanism underlying the fascinating stereoselectivity in azoalkane denitrogenation is presented. The two types of singlet diradicals, i.e. the puckered and planar conformations, were found to play important roles in the stereoselectivity in the photochemical denitrogenation of cyclic azoalkanes. The presence of the puckered singlet diradical, which is the third isomer in homolysis, resolves the mechanistic puzzle reported so far for the stereoselectivity in azoalkane denitrogenations.
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Abe M, Tada S, Mizuno T, Yamasaki K. Impact of Diradical Spin State (Singlet vs Triplet) and Structure (Puckered vs Planar) on the Photodenitrogenation Stereoselectivity of 2,3-Diazabicyclo[2.2.1]heptanes. J Phys Chem B 2016; 120:7217-26. [DOI: 10.1021/acs.jpcb.6b05342] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Manabu Abe
- Department of Chemistry,
Graduate School of Science, Hiroshima University (HIRODAI), 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Saori Tada
- Department of Chemistry,
Graduate School of Science, Hiroshima University (HIRODAI), 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Takemi Mizuno
- Department of Chemistry,
Graduate School of Science, Hiroshima University (HIRODAI), 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Katsuyoshi Yamasaki
- Department of Chemistry,
Graduate School of Science, Hiroshima University (HIRODAI), 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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