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Mukhopadhyay N, Sengupta A, Vijay AK, Lloret F, Mukherjee R. Ni(II) complexes of a new tetradentate NN'N''O picolinoyl-1,2-phenylenediamide-phenolate redox-active ligand at different redox levels. Dalton Trans 2022; 51:9017-9029. [PMID: 35638812 DOI: 10.1039/d2dt01043g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Three square planar nickel(II) complexes of a new asymmetric tetradentate redox-active ligand H3L2 in its deprotonated form, at three redox levels, open-shell semiquinonate(1-) π radical, quinone(0) and closed-shell dianion of its 2-aminophenolate part, have been synthesized. The coordinated ligand provides N (pyridine) and N' and N'' (carboxamide and 1,2-phenylenediamide, respectively) and O (phenolate) donor sites. Cyclic voltammetry on the parent complex [Ni(L2)] 1 in CH2Cl2 established a three-membered electron-transfer series (oxidative response at E1/2 = 0.57 V and reductive response at -0.32 V vs. SCE) consisting of neutral, monocationic and monoanionic [Ni(L2)]z (z = 0, 1+ and 1-). Oxidation of 1 with AgSbF6 affords [Ni(L2)](SbF6) (2) and reduction of 1 with cobaltocene yields [Co(η5-C5H5)2][Ni(L2)] (3). The molecular structures of 1·CH3CN, 2·0.5CH2Cl2 and 3·C6H6 have been determined by X-ray crystallography at 100 K. Characterization by 1H NMR, X-band EPR (gav = 2.006 (solid); 2.008 (CH2Cl2-C6H5CH3 glass); 80 K) and UV-VIS-NIR spectral properties established that 1, 2 and 3 have [NiII{(L2)˙2-}], [NiII{(L2)-}]+/1+ and [NiII{(L2)3-}]-/1- electronic states, respectively. Thus, the redox processes are ligand-centred. While 1 possesses paramagnetic St (total spin) = 1/2, 2 and 3 possess diamagnetic ground-state St = 0. Interestingly, the variable-temperature (2-300 K) magnetic measurement reveals that 1 with the St = 1/2 ground state attains the antiferromagnetic St = 0 state at a very low temperature, due to weak noncovalent interactions via π-π stacking. Density functional theory (DFT) electronic structural calculations at the B3LYP level of theory rationalized the experimental results. In the UV-VIS-NIR spectra, broad absorptions are recorded for 1 and 2 in the range of 800-1600 nm; however, such an absorption is absent for 3. Time-dependent (TD)-DFT calculations provide a very good fit with the experimental spectra and allow us to identify the observed electronic transitions.
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Affiliation(s)
- Narottam Mukhopadhyay
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal 741 246, India
| | - Arunava Sengupta
- Department of Chemistry, Techno India University, West Bengal, Kolkata 700091, India
| | - Aswin Kottapurath Vijay
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal 741 246, India
| | - Francesc Lloret
- Departament de Química Inorgànica/Instituto de Ciencia Molecular (ICMOL), Universitat de València, Polígono de la Coma, s/n, 46980 Paterna, València, Spain
| | - Rabindranath Mukherjee
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India.
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Sarkar P, Sarmah A, Mukherjee C. Where is the unpaired electron density? A combined experimental and theoretical finding on the geometric and electronic structures of the Co( iii) and Mn( iv) complexes of the unsymmetrical non-innocent pincer ONS ligand. Dalton Trans 2022; 51:16723-16732. [DOI: 10.1039/d2dt01868c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The geometry and electronic structures of the Co and Mn complexes of the pincer H3LONS ligand composed of both hard and soft donor atoms at the coordinating sites are reported.
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Affiliation(s)
- Prasenjit Sarkar
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Amrit Sarmah
- Department of Molecular Modelling, Institute of Organic Chemistry and Biochemistry ASCR, v.v.i. Flemingovo nám. 2, CZ-166 10 Prague 6, Czech Republic
- Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University Olomouc, 78371 Olomouc, Czech Republic
| | - Chandan Mukherjee
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
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Nasibipour M, Safaei E, Moaddeli A, Masoumpour MS, Wojtczak A. Biradical o-iminobenzosemiquinonato(1-) complexes of nickel(ii): catalytic activity in three-component coupling of aldehydes, amines and alkynes. RSC Adv 2021; 11:12845-12859. [PMID: 35423810 PMCID: PMC8697240 DOI: 10.1039/d0ra10248b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 03/22/2021] [Indexed: 11/21/2022] Open
Abstract
The six-coordinated bis-o-iminosemiquinone complex, NiL2 BIS, in which LBIS is the o-iminosemiquinone 1-electron oxidized form of the tridentate o-aminophenol benzoxazole-based ligand H2LBAP, was synthesized and characterized. The crystal structure of the complex reveals octahedral geometry with a NiN4O2 coordination sphere in which Ni(ii) has been surrounded by two tridentate LBIS ligands. This compound exhibits (S Ni = 1) with both spin and orbital contribution to the magnetic moment and antiferromagnetic coupling between two electrons on two LBIS ligands which results in a triplet spin ground state (S = 1). The electronic transitions and the electrochemical behavior of this open-shell molecule are presented here, based on experimental observations and theoretical calculations. The electrochemical behavior of NiL2 BIS was investigated by cyclic voltammetry and indicates ligand-centered redox processes. Three-component coupling of aldehydes, amines and alkynes (A3-coupling) was studied in the presence of the NiL2 BIS complex, and the previously reported four-coordinated bis-o-iminosemiquinone NiL2 NIS. Furthermore, among these two o-iminobenzosemiquinonato(1-) complexes of Ni(ii) (NiL2 NIS and NiL2 BIS), NiL2 NIS was found to be an efficient catalyst in A3-coupling at 85 °C under solvent-free conditions and can be recovered and reused for several cycles with a small decrease in activity.
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Affiliation(s)
- Mina Nasibipour
- Department of Chemistry, College of Sciences, Shiraz University 71454 Shiraz Iran
| | - Elham Safaei
- Department of Chemistry, College of Sciences, Shiraz University 71454 Shiraz Iran
| | - Ali Moaddeli
- Department of Chemistry, College of Sciences, Shiraz University 71454 Shiraz Iran
| | | | - Andrzej Wojtczak
- Nicolaus Copernicus University, Faculty of Chemistry 87-100 Torun Poland
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Paul GC, Sarkar P, Sarmah A, Shaw P, Maity S, Mukherjee C. A combined experimental and theoretical study on a single, unsupported oxo-bridged Mn(III,III) dimer coordinated to two iminobenzosemiquinone π-radical anions. Dalton Trans 2021; 50:8768-8775. [PMID: 34085670 DOI: 10.1039/d1dt00489a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ligand H2LAP comprises a non-innocent 2-aminophenol unit and an innocent bis(pyridin-2-ylmethyl)amine unit. The ligand, upon reaction with an equivalent amount of Mn(ClO4)2·6H2O in the presence of Et3N under air in MeOH, provided a mono(oxo)-bridged dinuclear Mn2 complex ({[(LISQ)MnIII-O-MnIII(LISQ)][(ClO4)]2}; 1). X-ray crystal structure analysis of complex 1 revealed that in the dicationic unit, the physical oxidation state of each Mn ion was +III and the 2-aminophenol unit of ligand H2LAP was in its one-electron oxidized iminobenzosemiquinone form. 1H-NMR measurement of complex 1 confirmed that the complex acquired a diamagnetic ground state (St = 0). Thus, antiferromagnetic couplings among the paramagnetic centers were realized. The UV-Vis-NIR spectrum of complex 1 was consisted of ligand-to-metal charge-transfer transitions in the visible region, while ligand-to-metal and metal-to-ligand charge-transfer transitions were noticed in the near-infrared region due to the presence of iminobenzosemiquinone radical units. The cyclic voltammogram of the complex showed three one-electron oxidation waves and two one-electron reduction waves. While the first two oxidation processes were metal-based, the two successive reductions were ligand-centered. DFT-based theoretical studies confirmed the assignment.
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Affiliation(s)
- Ganesh Chandra Paul
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India. and Department of Chemistry, ICFAI Science School, ICFAI University Tripura, Agartala, 799210, Tripura(W), India
| | - Prasenjit Sarkar
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
| | - Amrit Sarmah
- Department of Molecular Modelling, Institute of Organic Chemistry and Biochemistry ASCR, v.v.i. Flemingovo nám. 2, CZ-166 10 Prague 6, Czech Republic and Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University Olomouc, 78371 Olomouc, Czech Republic
| | - Prantick Shaw
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
| | - Suvendu Maity
- Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata, 700103, India
| | - Chandan Mukherjee
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
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Mukherjee R. Assigning Ligand Redox Levels in Complexes of 2-Aminophenolates: Structural Signatures. Inorg Chem 2020; 59:12961-12977. [PMID: 32881491 DOI: 10.1021/acs.inorgchem.0c00240] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The purpose of this Viewpoint is to provide a broad-ranging update of advances in the coordination chemistry of redox-active (noninnocent) 2-aminophenolates, with emphasis on two ligand backbone structural parameters, the average of C-O and C-N (C-O/N) bond distances and Δa values, signifying the degree of bond-length alternation in the six-membered ring, in order to identify the redox level of the coordinated ligands. In the absence of magnetic, spectroscopic, and redox results, it has been established that it is possible to assign the electronic ground state of a coordination complex of 2-aminophenolates with consideration of charge, metal-ligand bond distances, and two very promising ligand backbone structural parameters. From a closer look at the sensitive ligand backbone metrical parameters of a diversified group of about 120 transition-metal complexes, a few very useful generalizations have been made.
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Sarkar P, Ghorai S, Chandra Paul G, Khannam M, Barman S, Mukherjee C. Synthesis, characterization and study on the dissimilar reactivity of a Ni(II)-bis(iminosemiquinone) complex core to ligand-appended hemilabile –CH2OH and –CH2NH2 units. Inorganica Chim Acta 2020. [DOI: 10.1016/j.ica.2019.119340] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Dutta D, Kundu S, Ghosh P. A Diruthenium Complex of an N-Pyridyl-o-aminophenol Derivative: A Route to Mixed Valency. Chemistry 2019; 25:14901-14911. [PMID: 31411776 DOI: 10.1002/chem.201903028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Indexed: 11/06/2022]
Abstract
An N-pyridyl-o-aminophenol derivative that stabilises mixed-valence states of ruthenium ions is disclosed. A diruthenium complex, [(LIQ 0 )Ru2 Cl5 ]⋅MeOH (1⋅MeOH) is successfully isolated, in which LIQ 0 is the o-iminobenzoquinone form of 2-[(3-nitropyridin-2-yl)amino]phenol (LAP H2 ). In 1, LIQ 0 oriented towards one ruthenium centre is a non-innocent NO-donor redox ligand, whereas another oriented towards another ruthenium centre is an innocent pyridine-donor redox ligand. Complex 1 is a diruthenium(II,III) mixed-valence complex, [RuII (LIQ 0 )(μ-Cl)2 RuIII ], with a minor contribution from the diruthenium(III,III) state. [RuIII (LISQ .- )(μ-Cl)2 RuIII ] contains LISQ .- , which is the o-iminobenzosemiquinonate anion radical form of the ligand. Complexes 1- and 1+ are diruthenium(II,II), [RuII (LIQ 0 )(μ-Cl)2 RuII ], and diruthenium(III,III), [RuIII (LIQ 0 )(μ-Cl)2 RuIII ], complexes, respectively, of LIQ 0 . Complex 12- is a diruthenium(II,II) complex of the o-iminobenzosemiquinonate anion radical (LISQ .- ), [RuII (LISQ .- )(μ-Cl)2 RuII ], with a minor contribution from the diruthenium(III,II) form, [RuIII (LAP 2- )(μ-Cl)2 RuII ]. Complex 12+ is a diruthenium(III,IV) mixed-valence complex of LIQ 0 , [RuIII (LIQ 0 )(μ-Cl)2 RuIV ]. Complexes 1 and 12+ exhibit inter-valence charge-transfer transitions at λ=1300 and 1370 nm, respectively.
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Affiliation(s)
- Debarpan Dutta
- Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata, 700103, West Bengal, India
| | - Suman Kundu
- Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata, 700103, West Bengal, India
| | - Prasanta Ghosh
- Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata, 700103, West Bengal, India
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Paul GC, Sarkar P, Mukherjee C. Effect of H-bond and molecular geometry towards innocent and non-innocent behavior of 3,5-di-tert-butyl-2-aminophenol units attached to a piperazine backbone: Co(III) and Cu(II) complexes. Inorganica Chim Acta 2019. [DOI: 10.1016/j.ica.2018.10.048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Safaei E, Balaghi SE, Chiang L, Clarke RM, Martelino D, Webb MI, Wong EWY, Savard D, Walsby CJ, Storr T. Stabilization of different redox levels of a tridentate benzoxazole amidophenoxide ligand when bound to Co(iii) or V(v). Dalton Trans 2019; 48:13326-13336. [DOI: 10.1039/c9dt02865j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The electronic structure of Co and V complexes of a tridentate benzoxazole-containing aminophenol ligand NNOH2 were characterized by both experimental and theoretical methods.
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Affiliation(s)
- Elham Safaei
- Department of Chemistry
- College of Science
- Shiraz University
- Shiraz
- Iran
| | | | - Linus Chiang
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Ryan M. Clarke
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Diego Martelino
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Michael I. Webb
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Edwin W. Y. Wong
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Didier Savard
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Charles J. Walsby
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Tim Storr
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
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Nitsche S, Schmitz S, Stirnat K, Sandleben A, Klein A. Controlling Nuclearity and Stereochemistry in Vanadyl(V) and Mixed Valent VIV/VVComplexes of Oxido-Pincer Pyridine-2,6-dimethanol Ligands. Z Anorg Allg Chem 2018. [DOI: 10.1002/zaac.201800352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sara Nitsche
- Institut für Anorganische Chemie; Universität zu Köln; Greinstraße 6 50939 Köln Germany
| | - Simon Schmitz
- Institut für Anorganische Chemie; Universität zu Köln; Greinstraße 6 50939 Köln Germany
| | - Kathrin Stirnat
- Institut für Anorganische Chemie; Universität zu Köln; Greinstraße 6 50939 Köln Germany
| | - Aaron Sandleben
- Institut für Anorganische Chemie; Universität zu Köln; Greinstraße 6 50939 Köln Germany
| | - Axel Klein
- Institut für Anorganische Chemie; Universität zu Köln; Greinstraße 6 50939 Köln Germany
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Paul GC, Das K, Maity S, Begum S, Srivastava HK, Mukherjee C. Geometry-Driven Iminosemiquinone Radical to Cu(II) Electron Transfer and Stabilization of an Elusive Five-Coordinate Cu(I) Complex: Synthesis, Characterization, and Reactivity with KO2. Inorg Chem 2018; 58:1782-1793. [DOI: 10.1021/acs.inorgchem.8b01931] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ganesh Chandra Paul
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Kanu Das
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Suvendu Maity
- Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata 700103, India
| | - Samiyara Begum
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Hemant Kumar Srivastava
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Chandan Mukherjee
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
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Liu FW, Bi J, Sun Y, Luo S, Kang P. Cobalt Complex with Redox-Active Imino Bipyridyl Ligand for Electrocatalytic Reduction of Carbon Dioxide to Formate. CHEMSUSCHEM 2018; 11:1656-1663. [PMID: 29577653 DOI: 10.1002/cssc.201800136] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 03/23/2018] [Indexed: 06/08/2023]
Abstract
An imino bipyridine cobalt(II) complex was developed for the electrocatalytic reduction of CO2 to formate in acetonitrile with a faradaic efficiency of approximately 80 %. For comparison, a symmetric bis-imino pyridine complex showed lower catalytic activity because of less conjugation in the system. Cyclic voltammetry, electron paramagnetic resonance and IR spectroscopy studies provided mechanistic details and the structures of the key intermediates. DFT calculations confirmed the role of large π-conjugated groups for stabilizing key intermediates through electronic conjugation.
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Affiliation(s)
- Fang-Wei Liu
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 29 Zhongguancun East Rd, Beijing, 100190, PR China
- University of Chinese Academy of Sciences, 19A Yuquan Rd, Beijing, 100049, PR China
| | - Jiaojiao Bi
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 29 Zhongguancun East Rd, Beijing, 100190, PR China
- University of Chinese Academy of Sciences, 19A Yuquan Rd, Beijing, 100049, PR China
| | - Yuanyuan Sun
- State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang University of Technology, Chaowang Road 18, Hangzhou, 310014, PR China
| | - Shuping Luo
- State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang University of Technology, Chaowang Road 18, Hangzhou, 310014, PR China
| | - Peng Kang
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 29 Zhongguancun East Rd, Beijing, 100190, PR China
- School of Chemical Engineering and Technology, Tianjin University, 135 Yaguan Rd, Tianjin, 300350, PR China
- University of Chinese Academy of Sciences, 19A Yuquan Rd, Beijing, 100049, PR China
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