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Phenyl(triazolyl)carbene revisited: Unique role of triazolyl group on carbene chemistry. J PHYS ORG CHEM 2021. [DOI: 10.1002/poc.4187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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2
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Wong CM, Fekete M, Nelson-Forde R, Gatus MRD, Rayner PJ, Whitwood AC, Duckett SB, Messerle BA. Harnessing asymmetric N-heterocyclic carbene ligands to optimise SABRE hyperpolarisation. Catal Sci Technol 2018; 8:4925-4933. [PMID: 30319759 PMCID: PMC6171487 DOI: 10.1039/c8cy01214h] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 07/17/2018] [Indexed: 01/06/2023]
Abstract
The catalytic signal amplification by reversible exchange process has become widely used for the hyperpolarisation of small molecules to improve their magnetic resonance detectability. It harnesses the latent polarisation of parahydrogen, and involves the formation of a labile metal complex that often contains an N-heterocyclic carbene (NHC) ligand (e.g. [Ir(H)2(NHC)(pyridine)3]Cl), which act as a polarisation transfer catalyst. Unfortunately, if the target molecule is too bulky, binding to the catalyst is poor and the hyperpolarisation yield is therefore low. We illustrate here the behaviour of a series of asymmetric NHC containing catalysts towards 3,4- and 3,5-lutidine in order to show how catalyst design can be used to dramatically improve the outcome of this catalytic process for sterically encumbered ligands.
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Affiliation(s)
- Chin Min Wong
- School of Chemistry , University of New South Wales , Sydney 2052 , Australia
- Department of Molecular Sciences , Macquarie University , North Ryde 2109 , Australia .
| | - Marianna Fekete
- Centre for Hyperpolarisation in Magnetic Resonance , York Science Park , University of York , Heslington , York YO10 5NY , UK .
| | - Rhianna Nelson-Forde
- Centre for Hyperpolarisation in Magnetic Resonance , York Science Park , University of York , Heslington , York YO10 5NY , UK .
| | - Mark R D Gatus
- Department of Molecular Sciences , Macquarie University , North Ryde 2109 , Australia .
| | - Peter J Rayner
- Centre for Hyperpolarisation in Magnetic Resonance , York Science Park , University of York , Heslington , York YO10 5NY , UK .
| | - Adrian C Whitwood
- Centre for Hyperpolarisation in Magnetic Resonance , York Science Park , University of York , Heslington , York YO10 5NY , UK .
| | - Simon B Duckett
- Centre for Hyperpolarisation in Magnetic Resonance , York Science Park , University of York , Heslington , York YO10 5NY , UK .
| | - Barbara A Messerle
- Department of Molecular Sciences , Macquarie University , North Ryde 2109 , Australia .
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Koohi M, Kassaee MZ, Haerizade BN, Ghavami M, Ashenagar S. Substituent effects on cyclonona-3,5,7-trienylidenes: a quest for stable carbenes at density functional theory level. J PHYS ORG CHEM 2015. [DOI: 10.1002/poc.3418] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Maryam Koohi
- Department of Chemistry; Tarbiat Modares University; 14115-175 Tehran Iran
| | | | | | - Monireh Ghavami
- Industrial and mechanical engineering department; Islamic Azad University Qazvin branch; 34185-1416 Qazvin Iran
| | - Samaneh Ashenagar
- Department of Chemistry; Tarbiat Modares University; 14115-175 Tehran Iran
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Kassaee MZ, Koohi M, Mohammadi R, Ghavami M. 2,2,9,9-Tetramethylcyclonona-3,5,7-trienylidenevs. its heterocyclic analogues: A quest for stable carbenes at DFT. J PHYS ORG CHEM 2013. [DOI: 10.1002/poc.3189] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
| | - Maryam Koohi
- Department of Chemistry; Tarbiat Modares University; P.O. Box 14115-175 Tehran Iran
| | - Reza Mohammadi
- Department of Chemistry; Tarbiat Modares University; P.O. Box 14115-175 Tehran Iran
| | - Monireh Ghavami
- Department of Chemistry; Tarbiat Modares University; P.O. Box 14115-175 Tehran Iran
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Hirai K, Hatanaka K, Yamaguchi T, Miyajima A, Kitagawa T, Tomioka H. Generation and reactivities of triplet diphenylcarbenes protected by bulky groups as para substituents. J PHYS ORG CHEM 2011. [DOI: 10.1002/poc.1898] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Katsuyuki Hirai
- Instrumental Analysis Facilities, Social Cooperation Research Center; Mie University; Tsu; Mie; 514-8507; Japan
| | - Keiji Hatanaka
- Department of Chemistry for Materials, Graduate School of Engineering; Mie University; Tsu; Mie; 514-8507; Japan
| | - Tsuyoshi Yamaguchi
- Department of Chemistry for Materials, Graduate School of Engineering; Mie University; Tsu; Mie; 514-8507; Japan
| | - Akiko Miyajima
- Department of Chemistry for Materials, Graduate School of Engineering; Mie University; Tsu; Mie; 514-8507; Japan
| | - Toshikazu Kitagawa
- Department of Chemistry for Materials, Graduate School of Engineering; Mie University; Tsu; Mie; 514-8507; Japan
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Hirai K, Bessho K, Kitagawa T, Tomioka H. Triplet diphenylcarbene protected by iodine and bromine groups. J PHYS ORG CHEM 2010. [DOI: 10.1002/poc.1651] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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7
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Affiliation(s)
- Katsuyuki Hirai
- Life Science Research Center, Mie University, Tsu, Mie 514-8507, Japan, Corporate Research and Development Group, Sharp Corporation,Tenri, Nara 632-8567, Japan, Department of Applied Chemistry, Aichi Institute of Technology, Toyota, Aichi 470-0392, Japan, and Nagoya Industrial Science Research Institute, Nagoya, Aichi 464-0819, Japan
| | - Tetsuji Itoh
- Life Science Research Center, Mie University, Tsu, Mie 514-8507, Japan, Corporate Research and Development Group, Sharp Corporation,Tenri, Nara 632-8567, Japan, Department of Applied Chemistry, Aichi Institute of Technology, Toyota, Aichi 470-0392, Japan, and Nagoya Industrial Science Research Institute, Nagoya, Aichi 464-0819, Japan
| | - Hideo Tomioka
- Life Science Research Center, Mie University, Tsu, Mie 514-8507, Japan, Corporate Research and Development Group, Sharp Corporation,Tenri, Nara 632-8567, Japan, Department of Applied Chemistry, Aichi Institute of Technology, Toyota, Aichi 470-0392, Japan, and Nagoya Industrial Science Research Institute, Nagoya, Aichi 464-0819, Japan
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Gu SY, Su MD. Theoretical designs for triplet ground-state carbenes: A target for experimental studies. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.06.092] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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10
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Kawano M, Hirai K, Tomioka H, Ohashi Y. Structure Determination of Triplet Diphenylcarbenes by in Situ X-ray Crystallographic Analysis. J Am Chem Soc 2007; 129:2383-91. [PMID: 17263535 DOI: 10.1021/ja067306b] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Crystalline-state photoreactions of the following diphenyldiazomethanes were investigated by in situ X-ray crystallography, spectroscopy, and theoretical calculations: bis(2,4,6-trichlorophenyl)diazomethane (1-N2), bis(2,4,6-tribromophenyl)diazomethane (2-N2), bis(2,6-dibromo-4-methylphenyl)diazomethane (3-N2), bis(2,6-dibromo-4-tert-butylphenyl)diazomethane (4-N2), (2,4,6-tribromophenyl)-(2,6-dimethyl-4-tert-butylphenyl)diazomethane (5-N2), bis(4-bromophenyl)diazomethane(6-N2), and diazofluorene (7-N2). Crystal structures of photoinduced triplet diphenylcarbenes (DPCs) of 1, 2, and 4 were determined. We found remarkable differences between their structural information obtained in the crystalline state and that previously obtained spectroscopically in a glass matrix. Although the triplet DPCs of 1, 2, and 4 have significantly different stabilities in solution, only subtle differences in their structural parameters, except for their C(:)-Ar bond lengths, are observed. It is noteworthy that the average bond length of C(:)-Ar for 4 (1.374 A) is considerably shorter than those for (3)1 and (3)2 (1.430 and 1.428 A, respectively), provided that the two C(:)-Ar bonds being compared were chemically equivalent. The most likely explanations for the small and large differences in bond lengths in 1, 2, and 4 may be derived from the packing effect. The packing patterns of 1 and 2 are identical, but that of 4 is totally different from those of 1 and 2. Moreover, these results are interpreted as indicating that triplet DPCs undergo relaxation upon softening of the environments. Theoretical calculations indicate that the potential energy surface of triplet DPCs in terms of the carbene angle is extremely flat and changes in the angles have little effect on the energies. Triplet DPCs with a sterically congested carbene center are trapped in a structure dictated by the precursor structure in a rigid matrix, even if this is not the thermodynamically most stable geometry, but undergo geometrical relaxation upon softening the matrix to relieve steric compression. ESR studies indicate that the interplanar angles are more flexible than the bond angles.
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Affiliation(s)
- Masaki Kawano
- Department of Chemistry and Materials Science, Tokyo Institute of Technology, Tokyo 152-8551, Japan.
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Furukawa K, Takui T, Itoh K, Watanabe T, Hirai K, Tomioka H. Electronic and Molecular Structure of Room-Temperature Stable Triplet Carbene as Studied by ESR Spectroscopy. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587259608033685] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Katsuhiko Furukawa
- a Advanced Science and Technology Center for Cooperative Research , Kyushu University , 6-1 Kasugakoen, Kasuga, Fukuoka , 816 , Japan
| | - Takeji Takui
- b Department of Chemistry, Faculty of Science , Osaka City University , 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka , 558 , Japan
| | - Koichi Itoh
- c Department of Material Science, Faculty of Science , Osaka City University , 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka , 558 , Japan
| | - Tetsuya Watanabe
- d Chemistry Department for Materials, Faculty of Engineering , Mie University , Uehama, Tsu, Mie , 514 , Japan
| | - Katsuyuki Hirai
- d Chemistry Department for Materials, Faculty of Engineering , Mie University , Uehama, Tsu, Mie , 514 , Japan
| | - Hideo Tomioka
- d Chemistry Department for Materials, Faculty of Engineering , Mie University , Uehama, Tsu, Mie , 514 , Japan
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12
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Itoh T, Nakata Y, Hirai K, Tomioka H. Triplet Diphenylcarbenes Protected by Trifluoromethyl and Bromine Groups. A Triplet Carbene Surviving a Day in Solution at Room Temperature. J Am Chem Soc 2005; 128:957-67. [PMID: 16417387 DOI: 10.1021/ja056575j] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two types of diphenyldiazomethanes having two trifluoromethyl and two bromine groups at the ortho positions, either in unsymmetrical or in symmetrical fashion, that is, (2,6-dibromo-4-phenylphenyl)[4-phenyl-2,6-bis(trifluoromethyl)phenyl]diazomethane (U-1-N2) and bis(2-bromo-4-phenyl-6-trifluoromethylphenyl)diazomethane (S-1-N2), are prepared. Triplet diphenylcarbenes (U-(3)1 or S-(3)1) are generated from those precursors and are characterized by ESR, UV/vis spectroscopy at low temperature, as well as time-resolved UV/vis spectroscopy at room temperature. Those carbenes are shown to be at least 2 orders of magnitude less reactive than the most stable triplet diphenylcarbene thus far known, that is, bis(2,6-dibromo-4-phenylphenyl)carbene. It has been also shown that S-(3)1 is significantly more stable than U-(3)1 even though both have the same two kinds of substituents. It is suspected that the perpendicular alignment of the two most bulky groups is a more effective way to shield the carbenic center than the planar one. By this way, triplet substituted diphenylcarbene surviving nearly a day in solution at room temperature is realized for the first time.
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Affiliation(s)
- Tetsuji Itoh
- Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan
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13
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Tsuchiya Y, Matsuno M, Itoh T, Hirai K, Tomioka H. A Tris(carbene) Constructed with Stable Triplet Carbene Units. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2005. [DOI: 10.1246/bcsj.78.2037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Itoh T, Matsuno M, Kamiya E, Hirai K, Tomioka H. Preparation of Copper Ion Complexes of Sterically Congested Diaryldiazomethanes Having a Pyridine Ligand and Characterization of Their Photoproducts. J Am Chem Soc 2005; 127:7078-93. [PMID: 15884951 DOI: 10.1021/ja0424225] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To realize fairly stable high-spin polycarbenes by utilizing heterospin systems comprising 2p spins of organic radicals and 3d spins of magnetic metal ions, we prepared dianthryldiazomethanes having two pyridyl groups at the 2,2'- or 2,7-positions, that is, bis[10-(4-tert-butyl-2,6-dimethylphenyl)-2-(4-pyridyl)-9-anthryl]diazomethane (2,2'-DPy-1-N(2)) and [10-(4-tert-butyl-2,6-dimethylphenyl)-9-anthryl][(10-(4-tert-butyl-2,6-dimethylphenyl)-2,7-di(4-pyridyl)-9-anthryl]diazomethane (2,7-DPy-1-N(2)). The triplet carbene DPy-(3)1 generated by photolysis of DPy-1-N(2) was characterized by ESR and UV-vis spectroscopy in a matrix at low temperature as well as by time-resolved UV-vis in solution at room temperature. The results showed that the triplet carbene DPy-(3)1 was destabilized to some extent as opposed to the parent triplet carbene before pyridination, but it was still fairly persistent, having a half-life of more than 30 min in solution at room temperature. Photoproducts from the complex between DPy-1-N(2) and Cu(hfac)(2) were characterized in a similar manner, and the results suggested that the generated carbene centers interacted magnetically with the Cu(II) ion to form a high-spin species with significant thermal stability. The fact that no significant signals due to the isolated triplet carbene DPy-(3)1 were observed suggested that the pyridine moiety binds with Cu(hfac)(2) in a nearly quantitative manner under these cryogenic conditions. Magnetic measurements of the photoproduct using a superconducting quantum interference device (SQUID) magneto/susceptometer were performed to determine the spin state of the complex. The temperature dependence of the molar paramagnetic susceptibility indicated the presence of ferromagnetic interaction. The field dependences of magnetization for the complexes, expressed using M versus H/T plots, were analyzed in terms of the two-component Brillouin function to be S = 3.18 (F = 0.66) and S = 0.02 (F = 0.23) for the 1:1 complex of 2,7-DPy-1 and Cu(hfac)(2) and S = 2.70 (F = 0.33) and S = 0.49 (F = 0.11) for the 1:1 complex of 2,2'-DPy-1 and Cu(hfac)(2).
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Affiliation(s)
- Tetsuji Itoh
- Chemistry Department for Materials, Faculty of Engineering, and Instrumental Analysis Facilities, Life Science Research Center, Mie University, Tsu, Mie 514-8507, Japan
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Monguchi K, Itoh T, Hirai K, Tomioka H. Triplet Diphenylcarbenes Protected by o-Aryl Groups. J Am Chem Soc 2004; 126:11900-13. [PMID: 15382925 DOI: 10.1021/ja047738r] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Diphenyldiazomethanes (2a-N(2)) having phenyl groups at the ortho positions were prepared and the corresponding diphenylcarbenes (2a) photolytically generated from them were characterized not only by the traditional product analysis method but also by ESR and UV/vis spectroscopy in a rigid organic matrix at low temperature and in laser flash photolysis in solution at room temperature. Product analysis indicated that fluorenes 4a are formed almost exclusively. Fluorene is most likely produced by the attack of singlet carbene (1)2a on an ortho carbon of the phenyl substituent to generate isofluorene, followed by 1,5-H shift. Irradiation of 2a-N(2) in a 2-methyltetrahydrofuran (2-MTHF) matrix at 77 K gave ESR signals ascribable to triplet carbenes ((3)2a). UV/vis spectra of (3)2a were obtained by irradiating 2a-N(2) under identical conditions. However, laser flash photolysis (LFP) of 2a-N(2) in degassed benzene at room temperature showed transient absorption bands completely different from those observed in photolysis in the 2-MTHF matrix at 77 K. The transient band decayed in first-order with a rate constant of 7.6 x 10(4) s(-1), which was not retarded by deuterium substitution of o-phenyl hydrogens. Essentially the same transient band was observed in LFP of fluorene 4a. The LFP of 2a-N(2) in nondegassed benzene gave transient absorption bands ascribable to triplet carbene (3)2a and the corresponding carbonyl oxide. The quenching rate constant of (3)2a by oxygen and the lifetime of (3)2a in the absence of oxygen were estimated by plotting the observed pseudo-first-order rate constant of the formation of the carbonyl oxide against the concentration of oxygen. They were 1.9 x 10(7) M(-1)s(-1) and 16 micros, respectively. Similar studies with diphenyldiazomethanes having a series of substituents (4-Ph, 3,5-(CF(3))(2), and 2-F) on the ortho-phenyl rings gave essentially identical results, indicating that those substituents exhibit little effect on overall reaction pathway. From those studies, it is suggested that triplet carbenes (3)2 are also trapped by the ortho-phenyl ring to give eventually fluorenes.
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Affiliation(s)
- Kyoko Monguchi
- Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan
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Yoshida KI, Iiba E, Nozaki Y, Hirai K, Takahashi Y, Tomioka H, Lin CT, Gaspar PP. Di(9-anthryl)carbene Revisited. Product Analysis and Spectroscopic Studies. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2004. [DOI: 10.1246/bcsj.77.1509] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Tomioka H, Watanabe T, Hattori M, Nomura N, Hirai K. Generation, reactions, and kinetics of sterically congested triplet diphenylcarbenes. Effects of bromine groups. J Am Chem Soc 2002; 124:474-82. [PMID: 11792219 DOI: 10.1021/ja010658s] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of polybrominated diphenylcarbenes (DPCs) are generated by irradiation of the corresponding precursor diazomethanes, and their reactivities are investigated by means of low-temperature spectroscopies as well as laser flash photolysis. Triplet bis(2,4,6-tribromophenyl)carbene was shown to decay by undergoing dimerization and to have a half-life of 1 s in a degassed benzene solution at room temperature, some 6 orders of magnitude longer-lived than the parent DPC. Anomalous effects of para substituents on the stability of the triplet are noted. Thus, while the replacement of a 4-bromine group with a methyl group resulted in a sharp decrease in the lifetime, introduction of a tert-butyl group resulted in a dramatic increase in the lifetime; triplet bis(2,6-dibromo-4-tert-butylphenyl)carbene was shown to have a half-life of 16 s in solution at room temperature. Attempts to increase the stability of these polybrominated DPCs by buttressing effects of a m-bromine group and by the synergetic effect of bromine and methyl groups are also described.
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Affiliation(s)
- Hideo Tomioka
- Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan
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Hu Y, Ishikawa Y, Hirai K, Tomioka H. Spectroscopic and Product Studies of the Effect of Para Substituents on the Reactivity of Triplet Bis(2,6-dimethylphenyl)carbenes. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2001. [DOI: 10.1246/bcsj.74.2207] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Kawano M, Hirai K, Tomioka H, Ohashi Y. Structure Analysis of a Transient Triplet Carbene Trapped in a Crystal. J Am Chem Soc 2001. [DOI: 10.1021/ja0106366] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Masaki Kawano
- Contribution from the CREST, Japan Science and Technology Corporation, Kawaguchi, Saitama 332-0012 Japan, Department of Chemistry and Materials Science, Tokyo Institute of Technology, Tokyo 152-8551, Japan, and Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan
| | - Katsuyuki Hirai
- Contribution from the CREST, Japan Science and Technology Corporation, Kawaguchi, Saitama 332-0012 Japan, Department of Chemistry and Materials Science, Tokyo Institute of Technology, Tokyo 152-8551, Japan, and Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan
| | - Hideo Tomioka
- Contribution from the CREST, Japan Science and Technology Corporation, Kawaguchi, Saitama 332-0012 Japan, Department of Chemistry and Materials Science, Tokyo Institute of Technology, Tokyo 152-8551, Japan, and Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan
| | - Yuji Ohashi
- Contribution from the CREST, Japan Science and Technology Corporation, Kawaguchi, Saitama 332-0012 Japan, Department of Chemistry and Materials Science, Tokyo Institute of Technology, Tokyo 152-8551, Japan, and Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan
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20
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Kirmse W. Carbene protonation. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s1079-350x(01)80003-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
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Itakura H, Mizuno H, Hirai K, Tomioka H. Generation, characterization, and kinetics of triplet Di[1,2,3,4,5,6, 7,8-octahydro-1,4:5,8-di(ethano)anthryl]carbene. J Org Chem 2000; 65:8797-806. [PMID: 11112607 DOI: 10.1021/jo001418i] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The title carbene has been generated by photolysis of the corresponding diazo precursors and studied by spectroscopic means, i. e., electron paramagnetic resonance (EPR) and UV/vis spectroscopy in matrixes at low temperature and laser-flash photolysis in solution at room temperature, with the product analysis. The results are compared with triplet di(2,3,5,6-tetramethylphenyl)carbene, an open-chain counterpart, which revealed that bicycloalkyl groups are acting as a fairly good kinetic protector for the triplet carbene as opposed to the open-chain counterpart. The formation of all-hydrocarbon triplet carbenes having a half-life over a second under normal conditions was realized for the first time. Effects of para-substituents on the structure and reactivities of the carbene are also investigated and discussed in terms of polar and spin electronic effects.
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Affiliation(s)
- H Itakura
- Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan
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Hirai K, Yasuda K, Tomioka H. Generation, Direct Observation and Kinetics of Triplet (2,4,6-Triisopropylphenyl)phenylcarbene. CHEM LETT 2000. [DOI: 10.1246/cl.2000.398] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Affiliation(s)
- Didier Bourissou
- Laboratoire d'Hétérochimie Fondamentale et Appliquée (UPRES-A CNRS 5069), 118 route de Narbonne, Université Paul Sabatier (Bât 2R1), F-31062 Toulouse Cedex 04, France, Centre de Recherche Rhône-Alpes, Elf-Atochem, BP 63, F-69493 Pierre Bénite, France, and Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255
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Strain and structure of sterically congested triplet carbenes. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s1527-4640(00)80005-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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25
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Hu Y, Hirai K, Tomioka H. Effect of Para Substituents on the Molecular and Electronic Structures of Sterically Congested Triplet Diphenylcarbenes. J Phys Chem A 1999. [DOI: 10.1021/jp991576h] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yingmo Hu
- Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan
| | - Katsuyuki Hirai
- Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan
| | - Hideo Tomioka
- Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan
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Persistent triplet carbenes. ACTA ACUST UNITED AC 1998. [DOI: 10.1016/s1079-350x(98)80009-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Affiliation(s)
- Hideo Tomioka
- Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514, Japan
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Kirschfeld A, Muthusamy S, Sander W. Dimesityldioxiran — ein in Substanz stabiles Dioxiran. Angew Chem Int Ed Engl 1994. [DOI: 10.1002/ange.19941062108] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Fujiwara Y, Sasaki M, Tanimoto Y, Itoh M. Transient absorption and fluorescence spectroscopies of the excited-state naphthylphenycarbenes. Chem Phys Lett 1988. [DOI: 10.1016/0009-2614(88)85061-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Sander WW. Chemiluminescence from arylcarbene oxidation: Phenylchlorocarbene and (2-chlorophenyl)carbene. ACTA ACUST UNITED AC 1987. [DOI: 10.1016/0584-8539(87)80146-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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