1
|
Akama H, Kojima KM, McKenzie I, Ito S. Producing Conventional and Transient Amino(mercapto)methyl Radicals by Addition of Muonium to a Crystalline Thioformamide (Mes*NHCH=S). Chemphyschem 2024; 25:e202300980. [PMID: 38515308 DOI: 10.1002/cphc.202300980] [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: 12/21/2023] [Revised: 03/21/2024] [Accepted: 03/21/2024] [Indexed: 03/23/2024]
Abstract
Muonium (Mu=μ+e-) is composed of a muon of light isotope of proton (μ+) and electron (e-) and can be used as a light surrogate for a hydrogen atom. In this paper, we investigated addition of muonium to a newly synthesized Mes*-substituted thioformamide (Mes*NHCH=S, Mes*=2,4,6-tBu3C6H2). Transverse-field muon spin rotation (TF-μSR) of a solution sample of the thioformamide confirmed addition of muonium to the sulfur atom leading to the corresponding C-centered radical [Mes*NHC(H)⋅-SMu]. Density functional theory (DFT) calculations assigned a conventional amino(mercapto)methyl radical, in which both nitrogen and carbon were slightly pyramidalized, and the calculated muon hyperfine coupling constant (hfcc) including the muon isotope effect was compatible with the experimentally determined parameter. However, the muon level-crossing resonance (μLCR) spectrum of an anisotropic crystalline sample indicated two paramagnetic species, and the major product showed the considerably larger muon hfcc compared with the conventional structure of the amino(mercapto)methyl radical. The unusual transient muoniated thioformamide with the larger muon hfcc that showed rapid relaxation could be only explained by a transient structure including planarization of the nitrogen and carbon atoms in Mes*NHC(H)⋅-SMu.
Collapse
Affiliation(s)
- Hikaru Akama
- Department of Applied Chemistry, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-H113 Ookayama, Meguro-ku, Tokyo, 152-8552, Japan
| | - Kenji M Kojima
- Centre for Molecular and Materials Science, TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3, Canada
| | - Iain McKenzie
- Centre for Molecular and Materials Science, TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3, Canada
| | - Shigekazu Ito
- Department of Applied Chemistry, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-H113 Ookayama, Meguro-ku, Tokyo, 152-8552, Japan
| |
Collapse
|
2
|
Walsgrove HTG, Percival PW, Gates DP. Probing Radical Addition to 1-Phosphabutadienes by Employing Muonium as a "Light Isotope" of Hydrogen. Chemistry 2024; 30:e202302869. [PMID: 37837229 DOI: 10.1002/chem.202302869] [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: 09/03/2023] [Revised: 10/08/2023] [Accepted: 10/11/2023] [Indexed: 10/15/2023]
Abstract
Understanding free radical addition to multiple bonds is important to elucidating the mechanistic details of addition polymerization reactions, albeit the fleeting radical intermediates are very difficult to detect by conventional methodologies. Muon spin spectroscopy (μSR) is a highly sensitive method that can detect radical species at 106 spins (cf. EPR: 1012 spins, NMR: 1018 spins). Herein, we employ μSR to detect the radical-addition products from three 1-phosphabutadiene monomers, P-analogues of isoprene. We show that muonium (Mu), a "light" H-atom surrogate, adds predominantly at the C4 position of the P1 =C2 -C3 =C4 moiety to give unprecedented 1-phosphaallyl radicals as the major products. Our structural assignments are supported by assignment of muon, phosphorus and proton hyperfine coupling constants using DFT-calculations. A minor radical product is also detected that is tentatively assigned to an PC3 -heterocyclic free radical. On the basis of DFT-predictions, we speculate that its formation may involve initial addition of Mu+ at the C3 position followed by electron capture. These studies provide rare insights into the prospective radical (or cationic) polymerization of 1-phosphabutadienes, which have previously been polymerized using anionic initiation.
Collapse
Affiliation(s)
- Henry T G Walsgrove
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
| | - Paul W Percival
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
- Centre for Molecular and Materials Science TRIUMF, Vancouver, British Columbia, V6T 2A3, Canada
| | - Derek P Gates
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
| |
Collapse
|
3
|
Abstract
Heteroatom-centered diradical(oid)s have been in the focus of molecular main group chemistry for nearly 30 years. During this time, the diradical concept has evolved and the focus has shifted to the rational design of diradical(oid)s for specific applications. This review article begins with some important theoretical considerations of the diradical and tetraradical concept. Based on these theoretical considerations, the design of diradical(oid)s in terms of ligand choice, steric, symmetry, electronic situation, element choice, and reactivity is highlighted with examples. In particular, heteroatom-centered diradical reactions are discussed and compared with closed-shell reactions such as pericyclic additions. The comparison between closed-shell reactivity, which proceeds in a concerted manner, and open-shell reactivity, which proceeds in a stepwise fashion, along with considerations of diradical(oid) design, provides a rational understanding of this interesting and unusual class of compounds. The application of diradical(oid)s, for example in small molecule activation or as molecular switches, is also highlighted. The final part of this review begins with application-related details of the spectroscopy of diradical(oid)s, followed by an update of the heteroatom-centered diradical(oid)s and tetraradical(oid)s published in the last 10 years since 2013.
Collapse
Affiliation(s)
- Alexander Hinz
- Institut für Anorganische Chemie (AOC), Karlsruher Institut für Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
| | - Jonas Bresien
- Institut für Chemie, Universität Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
| | - Frank Breher
- Institut für Anorganische Chemie (AOC), Karlsruher Institut für Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
| | - Axel Schulz
- Institut für Chemie, Universität Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
| |
Collapse
|
4
|
Ito S. Muon Spin Rotation/Resonance (μSR) for Studying Radical Reactivity of Unsaturated Organophosphorus Compounds. Chemistry 2022; 28:e202200843. [PMID: 35702738 PMCID: PMC9796767 DOI: 10.1002/chem.202200843] [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: 03/17/2022] [Indexed: 01/07/2023]
Abstract
The positive muon (μ+ ) can be regarded as a light isotope of proton and has been an important tool to study radical reactions of organic compounds. Recently, muons have been applied to produce short-lived paramagnetic species from the heavier unsaturated organic molecules including the p-block elements. This article overviews recent muon spin rotation/resonance (μSR) studies on the phosphorus analogs of alkenes, anthracenes, and cyclobutane-1,3-diyls together with the fundamentals of μSR. The acyclic phosphaalkene of P=C and phosphasilenes of P=Si can accept muonium (Mu=[μ+ e- ]) at the heavier double bonds, and the corresponding radicals have been characterized. The phosphorus atom in 9-phosphaanthracene, whose P=C double bond is stabilized by the peri-substituted CF3 groups, predominantly captures muonium to provide the corresponding paramagnetic fused heterocyclic system. The peri-trifluoromethyl groups are functional to promote the unprecedented light isotope effect of muon providing the planar three-cyclic molecular structure to consume the increased zero-point energy. The formally open-shell singlet 1,3-diphosphacyclobutane-2,4-diyl unit can accept muonium at the (ylidic) phosphorus or the skeletal radicalic carbon, and the corresponding paramagnetic phosphorus heterocycles can be characterized by μSR. The findings on these muoniation processes to the unsaturated phosphorus-containing compounds will contribute not only to development of novel paramagnetic functional species but also to progress on muon science.
Collapse
Affiliation(s)
- Shigekazu Ito
- Department of Applied ChemistrySchool of Materials and Chemical TechnologyTokyo Institute of Technology2-12-1-H113 Ookayama, Meguro-kuTokyo152-8552Japan
| |
Collapse
|
5
|
Chemistry of Several Sterically Bulky Molecules with P=P, P=C, and C≡P Bond. Molecules 2022; 27:molecules27051557. [PMID: 35268657 PMCID: PMC8911619 DOI: 10.3390/molecules27051557] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/18/2022] [Accepted: 02/20/2022] [Indexed: 02/04/2023] Open
Abstract
Several sterically protected, low-coordinate organophosphorus compounds with P=P, P=C, and C≡P bond are described in this study. Molecules such as diphosphenes, phosphaalkenes, 1-phosphaallenes, 1,3-diphosphaallenes, 3,4-diphosphinidenecyclobutenes, and phosphaalkynes are stabilized with an extremely bulky 2,4,6-tri-t-butylphenyl (Mes*) group. The synthesis, structures, physical, and chemical properties of these molecules are discussed, together with some successful applications in catalytic organic reactions.
Collapse
|
6
|
Goli M, Shahbazian S. Two-component density functional theory for muonic molecules: Inclusion of the electron–positive muon correlation functional. J Chem Phys 2022; 156:044104. [DOI: 10.1063/5.0077179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Mohammad Goli
- School of Nano Science, Institute for Research in Fundamental Sciences (IPM), Tehran 19395-5531, Iran
| | - Shant Shahbazian
- Department of Physics, Shahid Beheshti University, Evin, Tehran, Iran
| |
Collapse
|
7
|
Ito S, Akama H, Ueta Y, McKenzie I, Kojima KM. Muonium Addition to the Radicalic Carbon in 1,3-Diphosphacyclobutane-2,4-diyl. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2021. [DOI: 10.1246/bcsj.20210352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Shigekazu Ito
- Department of Applied Chemistry, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-H113, Ookayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Hikaru Akama
- Department of Applied Chemistry, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-H113, Ookayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Yasuhiro Ueta
- Department of Applied Chemistry, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-H113, Ookayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Iain McKenzie
- Centre for Molecular and Materials Science, TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3, Canada
| | - Kenji M. Kojima
- Centre for Molecular and Materials Science, TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3, Canada
| |
Collapse
|
8
|
Koshino K, Kojima KM, McKenzie I, Ito S. Muonium Addition to a peri-Trifluoromethylated 9-Phosphaanthracene Producing a High-Energy Paramagnetic π-Conjugated Fused Heterocycle. Angew Chem Int Ed Engl 2021; 60:24034-24038. [PMID: 34409713 DOI: 10.1002/anie.202109784] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Indexed: 01/08/2023]
Abstract
In this communication, we report muon spin rotation/resonance (μSR) studies for understanding radical reactivity of 10-mesityl-1,8-bis(trifluoromethyl)-9-phosphaanthracene. Transverse-field muon spin rotation (TF-μSR) and muon avoided level-crossing resonance (μLCR) measurements successfully visualized a paramagnetic species produced by regioselective addition of muonium (Mu) to the skeletal phosphorus atom. Density functional theory (DFT) calculations for the P-muoniation product suggested two possible isomers. Whereas the most stable isomer including the envelope-type phosphorus heterocycle shows considerably different hyperfine coupling constants (hfcs) from those of the TF-μSR and μLCR, the metastable structure accompanying the almost planar tricyclic π-conjugated skeleton could simulate the experimentally determined hfcs. The metastable planar π-conjugated paramagnetic tricyclic-fused skeleton is promoted by the larger zero-point energy due to the light muon (μ+ ), one ninth of the proton mass.
Collapse
Affiliation(s)
- Kota Koshino
- Department of Applied Chemistry, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-H113 Ookayama, Meguro-ku, Tokyo, 152-8552, Japan.,Present address: Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Kenji M Kojima
- Centre for Molecular and Materials Science, TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3, Canada
| | - Iain McKenzie
- Centre for Molecular and Materials Science, TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3, Canada
| | - Shigekazu Ito
- Department of Applied Chemistry, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-H113 Ookayama, Meguro-ku, Tokyo, 152-8552, Japan
| |
Collapse
|
9
|
Koshino K, Kojima KM, McKenzie I, Ito S. Muonium Addition to a
peri
‐Trifluoromethylated 9‐Phosphaanthracene Producing a High‐Energy Paramagnetic π‐Conjugated Fused Heterocycle. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202109784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Kota Koshino
- Department of Applied Chemistry School of Materials and Chemical Technology Tokyo Institute of Technology 2-12-1-H113 Ookayama, Meguro-ku Tokyo 152-8552 Japan
- Present address: Division of Chemistry and Biological Chemistry School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore
| | - Kenji M. Kojima
- Centre for Molecular and Materials Science TRIUMF 4004 Wesbrook Mall Vancouver BC V6T 2A3 Canada
| | - Iain McKenzie
- Centre for Molecular and Materials Science TRIUMF 4004 Wesbrook Mall Vancouver BC V6T 2A3 Canada
| | - Shigekazu Ito
- Department of Applied Chemistry School of Materials and Chemical Technology Tokyo Institute of Technology 2-12-1-H113 Ookayama, Meguro-ku Tokyo 152-8552 Japan
| |
Collapse
|
10
|
Ueta Y, Ito S. Scalable Orbital Tuning of the 1,3-Diphosphacyclobutane-2,4-diyl Unit of Singlet Biradicaloid. J Org Chem 2020; 85:14384-14390. [DOI: 10.1021/acs.joc.0c00512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yasuhiro Ueta
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo 152-8552, Japan
| | - Shigekazu Ito
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo 152-8552, Japan
| |
Collapse
|
11
|
Ito S. Investigation of Organic Molecules Using Elementary Subatomic Particle: Muon Spin Spectroscopy for Reaction Analysis of the Open-Shell Singlet Heterocycle. J SYN ORG CHEM JPN 2019. [DOI: 10.5059/yukigoseikyokaishi.77.800] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Shigekazu Ito
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology
| |
Collapse
|
12
|
Ito S, Kato N, Ueta Y, Mikami K, Kojima KM. Muon spin rotation (µSR) study of a sterically encumbered thioaldehyde. PHOSPHORUS SULFUR 2019. [DOI: 10.1080/10426507.2019.1603719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Shigekazu Ito
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Naoto Kato
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Yasuhiro Ueta
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Koichi Mikami
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Kenji M. Kojima
- High Energy Accelerator Research Organization (KEK-IMSS), Tokai, Ibaraki, Japan
- Centre for Molecular and Materials Science, TRIUMF, Vancouver, BC, Canada
| |
Collapse
|
13
|
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
| |
Collapse
|
14
|
Chandrasena L, Samedov K, McKenzie I, Mozafari M, West R, Gates DP, Percival PW. Free Radical Reactivity of a Phosphaalkene Explored Through Studies of Radical Isotopologues. Angew Chem Int Ed Engl 2019; 58:297-301. [PMID: 30450733 DOI: 10.1002/anie.201810967] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 11/15/2018] [Indexed: 12/13/2022]
Abstract
Muonium (Mu), an H atom analogue, is employed to probe the addition of free radicals to the P=C bond of a phosphaalkene. Specifically, two unprecedented muoniated free radicals, MesP. -CMu(Me)2 (1 a, minor product) and MesPMu-C. Me2 (1 b, major product), were detected by muon spin spectroscopy (μSR) when a solution of MesP=CMe2 (1: Mes=2,4,6-trimethylphenyl) was exposed to a beam of positive muons (μ+ ). The μ+ serves as a source of Mu (that is, Mu=μ+ +e- ). To confirm the identity of the major product 1 b, its spectral features were compared to its isotopologue, MesPH-C. (Me)CH2 Mu (2 a). Conveniently, 2 a is the sole product of the reaction of MesPH(CMe=CH2 ) (2) with Mu. For all observed radicals, muon, proton, and phosphorus hyperfine coupling constants were determined by μSR and compared to DFT-calculated values.
Collapse
Affiliation(s)
- Lalangi Chandrasena
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Kerim Samedov
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada
| | - Iain McKenzie
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada.,Centre for Molecular and Materials Science, TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3, Canada
| | - Mina Mozafari
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Robert West
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI, 53706, USA
| | - Derek P Gates
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada
| | - Paul W Percival
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| |
Collapse
|
15
|
Chandrasena L, Samedov K, McKenzie I, Mozafari M, West R, Gates DP, Percival PW. Free Radical Reactivity of a Phosphaalkene Explored Through Studies of Radical Isotopologues. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201810967] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Lalangi Chandrasena
- Department of Chemistry; Simon Fraser University; 8888 University Drive Burnaby BC V5A 1S6 Canada
| | - Kerim Samedov
- Department of Chemistry; University of British Columbia; 2036 Main Mall Vancouver BC V6T 1Z1 Canada
| | - Iain McKenzie
- Department of Chemistry; Simon Fraser University; 8888 University Drive Burnaby BC V5A 1S6 Canada
- Centre for Molecular and Materials Science; TRIUMF; 4004 Wesbrook Mall Vancouver BC V6T 2A3 Canada
| | - Mina Mozafari
- Department of Chemistry; Simon Fraser University; 8888 University Drive Burnaby BC V5A 1S6 Canada
| | - Robert West
- Department of Chemistry; University of Wisconsin-Madison; 1101 University Avenue Madison WI 53706 USA
| | - Derek P. Gates
- Department of Chemistry; University of British Columbia; 2036 Main Mall Vancouver BC V6T 1Z1 Canada
| | - Paul W. Percival
- Department of Chemistry; Simon Fraser University; 8888 University Drive Burnaby BC V5A 1S6 Canada
| |
Collapse
|