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Yang W, Wang W, Zhang L, Zhang L, Ruan H, Feng Z, Fang Y, Wang X. Persistent 2 c-3 e σ-bonded heteronuclear radical cations centered on S/Se and P/As atoms. Chem Commun (Camb) 2021; 57:5067-5070. [PMID: 33884392 DOI: 10.1039/d1cc01117k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The two-center three-electron (2c-3e) bonded species are important in chemical and biological science. Reported isolable 2c-3e σ-bonded species are usually constructed in homoatomic radicals. The one-electron oxidation of main-group heteronuclear species Nap(SPh)(P(Mes)2) (1), Nap(SePh)(P(Mes)2) (2), Nap(SPh)(As(Mes)2) (3) and Nap(SePh)(As(Mes)2) (4) produced persistent radical cations 1˙+-4˙+ in solution. Large couplings of heteroatoms in EPR spectra of 1˙+-4˙+, shorter bond distances and bigger Wiberg bond orders of Ch-Pn in 1˙+-4˙+ than those in 1-4 in DFT calculations indicate large amounts of spin densities over heteroatoms and the formation of 2c-3e σ-bonds between chalcogen and pnicogen atoms. This work provides evidence of 2c-3e σ-bonds constructed between main-group heteronuclears and rare examples of radical cations involving three-electron σ-bonds between S/Se and P/As atoms.
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Affiliation(s)
- Wenbang Yang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
| | - Wenqing Wang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China. and College of Chemistry and Material Science, Key Laboratory of Functional Molecular Solids, Ministry of Education, Anhui Laboratory of Molecule-Based Materials, Anhui Normal University, Wuhu, Anhui 241002, China.
| | - Leran Zhang
- College of Chemistry and Material Science, Key Laboratory of Functional Molecular Solids, Ministry of Education, Anhui Laboratory of Molecule-Based Materials, Anhui Normal University, Wuhu, Anhui 241002, China.
| | - Li Zhang
- Center of Materials Science and Engineering, Guangxi University of Science and Technology, Liuzhou, Guangxi 545006, China
| | - Huapeng Ruan
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
| | - Zhongtao Feng
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
| | - Yong Fang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
| | - Xinping Wang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
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Hirakawa F, Nakagawa H, Honda S, Ishida S, Iwamoto T. Trialkylphosphines Having a Bulky Phosphacyclopentane Backbone: Structural and Redox Properties Depending on the Exocyclic Alkyl Groups and EPR Observation of a Persistent Trialkylphosphine Radical Cation. J Org Chem 2020; 85:14634-14642. [PMID: 32700539 DOI: 10.1021/acs.joc.0c01393] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bulky phosphines and their redox properties have received increased attention in the view of useful auxiliary ligands for transition metal catalysts and Lewis-base components of frustrated Lewis pairs for chemical transformations. Herein we report the synthesis, structure, and properties of a series of trialkylphosphines 2R (R = methyl, ethyl, isopropyl, tert-butyl, 1-adamantyl) that possess the bulky 2,2,5,5-tetrakis(trimethylsilyl)-1-phosphacyclopentane as a structural backbone. Among these phosphines, 2Ad, which contains an adamantyl moiety, has a very large buried volume (%Vbur) for a trialkylphosphine (62.0) and shows a quasi-reversible oxidative wave at a lower oxidation potential (-0.12 V in CH2Cl2, vs ferrocene/ferrocenium couple) by cyclic voltammetry. The reaction of 2Ad with AgPF6 afforded a cationic silver aquo complex [Ag(2Ad)(H2O)]+[PF6]-, whereas the reaction with NOSbF6 gave a persistent phosphine radical cation [2Ad]•+. Based on the EPR spectra and DFT studies, the spin and positive charge of [2Ad]•+ are localized on the phosphorus atom.
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Affiliation(s)
- Fumiya Hirakawa
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Hiroshi Nakagawa
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Shunya Honda
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Shintaro Ishida
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Takeaki Iwamoto
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
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3
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Rama RJ, Maya C, Nicasio MC. Dialkylterphenyl Phosphine-Based Palladium Precatalysts for Efficient Aryl Amination of N-Nucleophiles. Chemistry 2020; 26:1064-1073. [PMID: 31743505 DOI: 10.1002/chem.201903279] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Indexed: 01/21/2023]
Abstract
A series of 2-aminobiphenyl palladacycles supported by dialkylterphenyl phosphines, PR2 Ar' (R=Me, Et, iPr, Cyp (cyclopentyl), Ar'=ArDipp2 , ArXyl2f , Dipp (2,6-C6H3-(2,6-C6H3-(CHMe2)2)2), Xyl=xylyl) have been prepared and structurally characterized. Neutral palladacycles were obtained with less bulky terphenyl phosphines (i.e., Me and Et substituents) whereas the largest phosphines provided cationic palladacycles in which the phosphines adopted a bidentate hemilabile k1 -P,η1 -Carene coordination mode. The influence of the ligand structure on the catalytic performance of these Pd precatalysts was evaluated in aryl amination reactions. Cationic complexes bearing the phosphines PiPr2 ArXyl2 and PCyp2 ArXyl2 were the most active of the series. These precatalysts have demonstrated a high versatility and efficiency in the coupling of a variety of nitrogen nucleophiles, including secondary amines, alkyl amines, anilines, and indoles, with electronically deactivated and ortho-substituted aryl chlorides at low catalyst loadings (0.25-0.75 mol % Pd) and without excess ligand.
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Affiliation(s)
- Raquel J Rama
- Departamento de Química Inorgánica, Universidad de Sevilla, Aptdo 1203, 41071, Sevilla, Spain
| | - Celia Maya
- Instituto de Investigaciones Químicas (IIQ), Departamento de Química Inorgánica and, Centro de Innovación en Química Avanzada (ORFEO-CINQA), Consejo Superior de Investigaciones Científicas (CSIC) and, Universidad de Sevilla, Avda. Américo Vespucio 49, 41092, Sevilla, Spain
| | - M Carmen Nicasio
- Departamento de Química Inorgánica, Universidad de Sevilla, Aptdo 1203, 41071, Sevilla, Spain
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Marín M, Moreno JJ, Alcaide MM, Álvarez E, López-Serrano J, Campos J, Nicasio MC, Carmona E. Evaluating stereoelectronic properties of bulky dialkylterphenyl phosphine ligands. J Organomet Chem 2019. [DOI: 10.1016/j.jorganchem.2019.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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5
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Marín M, Moreno JJ, Navarro‐Gilabert C, Álvarez E, Maya C, Peloso R, Nicasio MC, Carmona E. Synthesis, Structure and Nickel Carbonyl Complexes of Dialkylterphenyl Phosphines. Chemistry 2018; 25:260-272. [DOI: 10.1002/chem.201803598] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Indexed: 01/25/2023]
Affiliation(s)
- Mario Marín
- Departamento de Química InorgánicaUniversidad de Sevilla, Aptdo 1203 41071 Sevilla Spain
| | - Juan J. Moreno
- Instituto de Investigaciones Químicas (IIQ), Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA)Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla Avda. Américo Vespucio 49 41092 Sevilla Spain
| | - Carlos Navarro‐Gilabert
- Instituto de Investigaciones Químicas (IIQ), Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA)Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla Avda. Américo Vespucio 49 41092 Sevilla Spain
| | - Eleuterio Álvarez
- Instituto de Investigaciones Químicas (IIQ), Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA)Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla Avda. Américo Vespucio 49 41092 Sevilla Spain
| | - Celia Maya
- Instituto de Investigaciones Químicas (IIQ), Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA)Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla Avda. Américo Vespucio 49 41092 Sevilla Spain
| | - Riccardo Peloso
- Instituto de Investigaciones Químicas (IIQ), Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA)Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla Avda. Américo Vespucio 49 41092 Sevilla Spain
| | - M. Carmen Nicasio
- Departamento de Química InorgánicaUniversidad de Sevilla, Aptdo 1203 41071 Sevilla Spain
| | - Ernesto Carmona
- Instituto de Investigaciones Químicas (IIQ), Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA)Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla Avda. Américo Vespucio 49 41092 Sevilla Spain
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6
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Moreno JJ, Espada MF, Krüger E, López‐Serrano J, Campos J, Carmona E. Ligand Rearrangement and Hemilability in Rhodium(I) and Iridium(I) Complexes Bearing Terphenyl Phosphanes. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800169] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Juan José Moreno
- Instituto de Investigaciones Químicas (IIQ) Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO‐CINQA) Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla Avda. Américo Vespucio 49 41092 Sevilla Spain
| | - María F. Espada
- Instituto de Investigaciones Químicas (IIQ) Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO‐CINQA) Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla Avda. Américo Vespucio 49 41092 Sevilla Spain
| | - Eric Krüger
- Instituto de Investigaciones Químicas (IIQ) Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO‐CINQA) Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla Avda. Américo Vespucio 49 41092 Sevilla Spain
| | - Joaquín López‐Serrano
- Instituto de Investigaciones Químicas (IIQ) Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO‐CINQA) Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla Avda. Américo Vespucio 49 41092 Sevilla Spain
| | - Jesús Campos
- Instituto de Investigaciones Químicas (IIQ) Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO‐CINQA) Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla Avda. Américo Vespucio 49 41092 Sevilla Spain
| | - Ernesto Carmona
- Instituto de Investigaciones Químicas (IIQ) Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO‐CINQA) Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla Avda. Américo Vespucio 49 41092 Sevilla Spain
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7
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Gupta AK, Akkarasamiyo S, Orthaber A. Rich Coordination Chemistry of π-Acceptor Dibenzoarsole Ligands. Inorg Chem 2017; 56:4505-4512. [DOI: 10.1021/acs.inorgchem.7b00100] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Arvind Kumar Gupta
- Molecular Inorganic
Chemistry, Department of Chemistry, Ångström Laboratories, Uppsala University, Box 523, 751 20 Uppsala, Sweden
| | - Sunisa Akkarasamiyo
- Department of Organic Chemistry, Stockholm University, 106 91 Stockholm, Sweden
| | - Andreas Orthaber
- Molecular Inorganic
Chemistry, Department of Chemistry, Ångström Laboratories, Uppsala University, Box 523, 751 20 Uppsala, Sweden
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8
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Synthesis, properties, and some rhodium, iridium, and platinum complexes of a series of bulky m-terphenylphosphine ligands. Polyhedron 2016. [DOI: 10.1016/j.poly.2016.04.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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9
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Sasaki S, Shimizu Y, Yoshifuji M. Synthesis, Structure, and Properties of [4-Methyl-2,6-Bis(2-Methylphenyl)Phenyl]Bis(2,4,6-Triisopropylphenyl)Phosphine. PHOSPHORUS SULFUR 2015. [DOI: 10.1080/10426507.2014.984031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Shigeru Sasaki
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki Aza-Aoba, Aoba-ku, 980-8578, Sendai, Japan
| | - Yusuke Shimizu
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki Aza-Aoba, Aoba-ku, 980-8578, Sendai, Japan
| | - Masaaki Yoshifuji
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki Aza-Aoba, Aoba-ku, 980-8578, Sendai, Japan
- Present address: Department of Chemistry, The University of Alabama, Tuscaloosa, 35487-0336, Alabama, USA
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10
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Sasaki S, Izawa M, Yoshifuji M. Synthesis and Structure of Sterically Crowded Triarylphosphine Bearing 4-Bromo-2,6-Bis(4-tert-Butylphenyl)Phenyl Group. PHOSPHORUS SULFUR 2014. [DOI: 10.1080/10426507.2014.907291] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Shigeru Sasaki
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Masatoshi Izawa
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Masaaki Yoshifuji
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
- Present address of M. Yoshifuji: Department of Chemistry, The University of Alabama, Tuscaloosa, AL 35487-0336, USA
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11
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12
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Boeré RT, Zhang Y. A study of the pyramidality index in tris(2,4,6-triisopropylphenyl)phosphonium perchlorate. Acta Crystallogr C 2013; 69:1051-4. [PMID: 24005520 DOI: 10.1107/s0108270113020647] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 07/24/2013] [Indexed: 11/10/2022] Open
Abstract
The title compound, C45H70P(+)·ClO4(-) or [Tripp3PH(+)][ClO4(-)], was produced from the perchlorate salt of the corresponding radical cation Tripp3P(·+) through very slow H-atom abstraction reactions in a solution of 1,2-dimethoxyethane (Tripp is 2,4,6-triisopropylphenyl). The H atom on the P atom was located in a difference map and was freely refined with an isotropic displacement consistent with full occupancy [P-H = 1.37 (3) Å]. It is the most sterically congested triarylphosphonium salt yet to be reported and has a `propeller' arrangement of the three Tripp groups around the P atom, with the protonation site located along the molecular threefold axis. There are short contacts between the flanking isopropyl methine H atoms and the P atom [P···H = 1.99 (2)-2.17 (2) Å]. The sum of the angles around the P atom [Σ(C-P-C) = 349.9 (6)°] is a convenient index of pyramidality for tricoordinate centres. This value is significantly larger than in analogous Mes3PH(+) salts (Mes is mesityl or 2,4,6-trimethylphenyl), for which the average of the three reported structures in the literature is Σ(C-P-C) = 345.3 (6)°. For comparison, in the ubiquitous Ph3PH(+) salts, this parameter has a typical average value of only 333.3 (9)°. The value of Σ(C-P-C) in the title compound is midway between that of the neutral phosphane Tripp3P [334.4 (6)°] and the phosphoniumyl radical cation Tripp3P(·+) [359.8 (2)°]. This geometrical feature provides additional support for the assignment as a phosphonium salt.
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Affiliation(s)
- René T Boeré
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, Canada T1K 3M4.
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13
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Bullock JP, Bond AM, Boeré RT, Gietz TM, Roemmele TL, Seagrave SD, Masuda JD, Parvez M. Synthesis, characterization, and electrochemical studies of PPh(3-n)(dipp)(n) (dipp = 2,6-diisopropylphenyl): steric and electronic effects on the chemical and electrochemical oxidation of a homologous series of triarylphosphines and the reactivities of the corresponding phosphoniumyl radical cations. J Am Chem Soc 2013; 135:11205-15. [PMID: 23808375 DOI: 10.1021/ja403555d] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Activation barriers to the electrochemical oxidation for the series PPh3-n(dipp)n (dipp = 2,6-diisopropylphenyl) in CH2Cl2/Bu4NPF6 were measured using large amplitude FT ac voltammetry. Increasing substitution across this series, which offers the widest range of steric requirements across any analogous series of triarylphosphines reported to date, increases the energetic barrier to electron transfer; values of 18, 24, and 25 kJ mol(-1) were found for compounds with n = 1, 2, and 3, respectively. These values are significantly greater than those calculated for outer sphere activation barriers, with deviations between observed and calculated values increasing with the number of dipp ligands. This suggests that the steric congestion afforded by these bulky substituents imposes significant reorganizational energy on the electron transfer processes. This is the first investigation of the effect of sterics on the kinetics of heterogeneous electron transfer across a structurally homologous series. Increased alkyl substitution across the series also increases the chemical reversibility of the oxidations and decreases the oxidation peak potentials. As the compounds for which n = 1 and 2 are novel, the synthetic strategies employed in their preparation are described, along with their full spectroscopic, physical, and crystallographic characterization. Optimal synthesis when n = 1 is via a Grignard reagent, whereas when n = 2 an aryl copper reagent must be employed, as use of a Grignard results in reductive coupling. Chemical oxidation studies were performed to augment the electrochemical work; the O, S, and Se oxidation products for the parent triarylphosphines for which n = 1 and 2 were isolated and characterized.
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Affiliation(s)
- John P Bullock
- Division of Natural Sciences & Mathematics, Bennington College, Bennington, Vermont 05201, USA.
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Pan X, Chen X, Li T, Li Y, Wang X. Isolation and X-ray Crystal Structures of Triarylphosphine Radical Cations. J Am Chem Soc 2013; 135:3414-7. [DOI: 10.1021/ja4012113] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xiaobo Pan
- State Key Laboratory of Coordination Chemistry, School
of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Xiaoyu Chen
- State Key Laboratory of Coordination Chemistry, School
of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Tao Li
- State Key Laboratory of Coordination Chemistry, School
of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Yizhi Li
- State Key Laboratory of Coordination Chemistry, School
of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Xinping Wang
- State Key Laboratory of Coordination Chemistry, School
of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
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15
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Fleming CGE, Slawin AMZ, Athukorala Arachchige KS, Randall R, Bühl M, Kilian P. Synthetic and computational study of geminally bis(supermesityl) substituted phosphorus compounds. Dalton Trans 2013; 42:1437-50. [PMID: 23165805 DOI: 10.1039/c2dt31971c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reaction chemistry of an extremely sterically encumbered phosphinic chloride (Mes*)(2)P(=O)Cl (Mes* = 2,4,6-tri-t-butylphenyl, supermesityl) was investigated. This compound, as well as other compounds bearing two supermesityl groups placed geminally at the central phosphorus atom, shows extremely low reactivity at the phosphorus centre. Nevertheless, some synthetically significant transformations were possible. Reduction with hydridic reagents under forcing conditions yielded the phosphine oxide (Mes*)(2)P(=O)H and a secondary phosphine Mes*(2,4-tBu(2)C(6)H(3))PH. Deprotonation of (Mes*)(2)P(=O)H gave the corresponding phosphinite, which afforded very crowded tertiary phosphine oxides (Mes*)(2)P(=O)R (R = Me and Et) on reactions with electrophiles. While the reaction of the phosphine Mes*(2,4-tBu(2)C(6)H(3))PH with sulfur was surprisingly facile (although under forcing conditions), we have been unable to chlorinate or deprotonate this phosphine. All new compounds were fully characterised with multinuclear NMR, IR, Raman, MS, microanalyses and single crystal X-ray diffraction. Our computations (B3LYP and M06-2X level) show that strain energies of (synthetically accessible) geminally substituted compounds are extremely high (180 to 250 kJ mol(-1)), the majority of the strain is stored as boat distortions to the phenyl rings in Mes* substituents.
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Affiliation(s)
- Conor G E Fleming
- EaStChem School of Chemistry, University of St Andrews, Fife KY16 9ST, St Andrews, UK
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16
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Alberti A, Guerra M, Venturini A. An ESR and DFT revisitation of phosphonitroxides prompted by an ineffective ESR approach to the hydrophosphination of alkynes. RSC Adv 2013. [DOI: 10.1039/c3ra41929k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Benincori T, Marchesi A, Pilati T, Ponti A, Rizzo S, Sannicolò F. Chirality in the absence of rigid stereogenic elements: the design of configurationally stable C3-symmetric propellers. Chemistry 2009; 15:94-105. [PMID: 19072792 DOI: 10.1002/chem.200801505] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Residual stereoisomerism is a form of stereoisomerism scarcely considered so far for applicative purposes, though extremely interesting, since the production of stereoisomers does not involve classical rigid stereogenic elements. In three-bladed propeller-shaped molecules, a preferred stereomerization mechanism, related to the correlated rotation of the rings, allows the free interconversion of stereoisomers inside separated sets (the residual stereoisomers) that can interconvert through higher energy pathways. In light of possible future applications as chiral ligands for transition metals in stereoselective processes, some C(3)-symmetric phosphorus-centered propellers, which could exist as residual enantiomers, are synthesized and the possibility of resolving their racemates into residual antipodes is explored. While the tris(aryl)methanes are configurationally stable at room temperature, only selected tris(aryl)phosphane oxides display a configurational stability high enough to allow resolution by HPLC on a chiral stationary phase (CSP HPLC) at a semipreparative level at room temperature. Stability was evaluated through different techniques (circular dichroism (CD) signal decay, dynamic CSP HPLC (CSP DHPLC), dynamic NMR analysis (DNMR)) and the results compared and discussed. Phosphanes were found much less stable than the corresponding phosphane oxides, for which preliminary calculations suggest that the three-ring-flip enantiomerization mechanism (M(0)) would be easier than phosphorus pyramidal inversion. The parameters affecting the configurational stability of the residual enantiomers of C(3)-symmetric propellers are discussed.
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Affiliation(s)
- Tiziana Benincori
- Dipartimento di Scienze Chimiche ed Ambientali, Università dell'Insubria via Valleggio 11, 22100 Como, Italy
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Benincori T, Marchesi A, Mussini P, Pilati T, Ponti A, Rizzo S, Sannicolò F. Chirality in the Absence of Rigid Stereogenic Elements: The Absolute Configuration of Residual Enantiomers ofC3-Symmetric Propellers. Chemistry 2009; 15:86-93. [DOI: 10.1002/chem.200801489] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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19
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Boeré RT, Bond AM, Cronin S, Duffy NW, Hazendonk P, Masuda JD, Pollard K, Roemmele TL, Tran P, Zhang Y. Photophysical, dynamic and redox behavior of tris(2,6-diisopropylphenyl)phosphine. NEW J CHEM 2008. [DOI: 10.1039/b709602j] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ohzu Y, Goto K, Sato H, Kawashima T. Syntheses and structures of bowl-shaped triarylphosphines and their palladium(II) complexes. J Organomet Chem 2005. [DOI: 10.1016/j.jorganchem.2005.06.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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