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Sutton AL, Abrahams BF, Hudson TA, Robson R. A new fluorone-based bridging ligand for discrete and polymeric assemblies including Mo and W based [4+4] metallocycles. NEW J CHEM 2020. [DOI: 10.1039/d0nj02413a] [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 synthesis of a planar, trianionic, redox-active ligand is described, which is able to bridge metal centres and form [4+4] square anionic metallocycles.
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Affiliation(s)
| | | | | | - Richard Robson
- School of Chemistry
- University of Melbourne
- Parkville
- Australia
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2
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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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3
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Yamada S, Matsumoto T, Chang HC. Impact of Group 10 Metals on the Solvent-Induced Disproportionation of o-Semiquinonato Complexes. Chemistry 2019; 25:8268-8278. [PMID: 30963643 DOI: 10.1002/chem.201900172] [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: 01/11/2019] [Indexed: 01/29/2023]
Abstract
The oxidation of [MII (3,5-DTBCat)(DTBbpy)] (M=Ni ([Ni]), Pd ([Pd]), and Pt ([Pt]); 3,5-DTBCat=3,5-di-tert-butylcatecholato; DTBbpy=4,4'-di-tert-butyl-2,2'-bipyridine) afforded the dimeric {[NiII (3,5-DTBSQ)(DTBbpy)](PF6 )}2 ({[Ni](PF6 )}2 ; 3,5-DTBSQ=3,5-di-tert-butylsemiquinonato) and monomeric semiquinonato (SQ) complexes [MII (3,5-DTBSQ)(DTBbpy)](PF6 ) (M=Pd ([Pd](PF6 )) and Pt ([Pt](PF6 ))). The negative solvatochromic properties of the SQ complexes allowed us to estimate the relative order of their dipole moments: [Pd](PF6 )>[Pt](PF6 )>{[Ni](PF6 )}2 . The complexes [Pd](PF6 ) and [Pt](PF6 ) adopt monomeric structures and are stable in CH2 Cl2 and toluene, whereas they gradually disproportionate at room temperature to [M] and 3,5-di-tert-butylbenzoquinone (3,5-DTBBQ) in polar solvents such as THF, MeOH, EtOH, DMF, or DMSO. The results of spectroscopic studies suggested that the oxidized nickel complex adopts a monomeric structure ([Ni](PF6 )) in CH2 Cl2 , but a dimeric structure ({[Ni](PF6 )}2 ) in the other investigated solvents. In polar solvents, {[Ni](PF6 )}2 may disproportionate to [Ni] and 3,5-DTBBQ at 323 K, thereby demonstrating a significant solvent- and metal-dependence in temperature. The relative activities of {[Ni](PF6 )}2 and [M](PF6 ) toward disproportionation are related to the electrochemically estimated Kdis values in CH2 Cl2 and DMF. The present work demonstrates that solvent polarity and the dipole moments of the SQ complexes promote disproportionation, which can be controlled by a judicious choice of the metal ion, solvent, and temperature.
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Affiliation(s)
- Shota Yamada
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo, 112-8551, Japan
| | - Takeshi Matsumoto
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo, 112-8551, Japan
| | - Ho-Chol Chang
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo, 112-8551, Japan
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4
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Kamatchi TS, Mondal S, Scherer T, Bubrin M, Natarajan K, Kaim W. Near-Infrared-Absorbing Organometallic Diruthenium Complex Intermediates: Evidence for Bridging Anthrasemiquinone Formation and against Mixed Valency. Chemistry 2017; 23:17810-17816. [DOI: 10.1002/chem.201703888] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Indexed: 11/08/2022]
Affiliation(s)
| | - Sudipta Mondal
- Institut für Anorganische Chemie; Universität Stuttgart; Pfaffenwaldring 55 70550 Stuttgart Germany
| | - Thomas Scherer
- Institut für Anorganische Chemie; Universität Stuttgart; Pfaffenwaldring 55 70550 Stuttgart Germany
| | - Martina Bubrin
- Institut für Anorganische Chemie; Universität Stuttgart; Pfaffenwaldring 55 70550 Stuttgart Germany
| | | | - Wolfgang Kaim
- Institut für Anorganische Chemie; Universität Stuttgart; Pfaffenwaldring 55 70550 Stuttgart Germany
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5
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Zavakhina MS, Yushina IV, Samsonenko DG, Dybtsev DN, Fedin VP, Argent SP, Blake AJ, Schröder M. Halochromic coordination polymers based on a triarylmethane dye for reversible detection of acids. Dalton Trans 2017; 46:465-470. [PMID: 27957580 PMCID: PMC5436038 DOI: 10.1039/c6dt03969c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 12/05/2016] [Indexed: 12/20/2022]
Abstract
Chromeazurol B (Na2HL) is a pH-sensitive (halochromic) dye based on a hydroxytriarylmethane core and two carboxylate functional groups, which makes it suitable for the synthesis of coordination polymers. Two new coordination polymers [NaZn4(H2O)3(L)3]·3THF·3H2O (1) and [Zn3(H2O)3(μ2-OH2)(μ3-OH)(HL)2(H2L)]·2THF·3H2O (2) incorporating Chromeazurol B linkers have been prepared and characterised. The structure of 1 comprises pentanuclear heterometallic {Zn4Na} nodes linked by six L3- anions to give a layered structure with a honeycomb topology. 2 crystallizes as a double-chain ribbon (ladder) structure with two types of metal node: a mononuclear Zn(ii) cation and tetranuclear {Zn(ii)}4 cluster. Chromeazurol B anions link each tetranuclear cluster to four individual Zn(ii) cations and each Zn(ii) cation with four tetranuclear clusters. Both compounds show pH-sensitivity in water solution which can be observed visually, giving the first example of a halochromic coordination polymer. The halochromic properties of 1 towards HCl vapors were systematically investigated. As-synthesized violet-grey 1 reversibly changes color from orange to pink in the presence of vapors of 2 M and 7 M HCl, respectively. The coordination of the Chromeazurol B anion at each color stage was examined by diffuse reflectance spectroscopy and FT-IR measurements. The remarkable stability of 1 to acid and the observed reversible and reproducible color changes provide a new design for multifunctional sensor materials.
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Affiliation(s)
- Marina S Zavakhina
- Nikolaev Institute of Inorganic Chemistry, Russian Academy of Sciences, Siberian Branch, Acad. Lavrentiev Ave., 3, Novosibirsk, 630090, Russian Federation. and Novosibirsk State University, Pirogov str., 2, Novosibirsk, 630090, Russian Federation
| | - Irina V Yushina
- Nikolaev Institute of Inorganic Chemistry, Russian Academy of Sciences, Siberian Branch, Acad. Lavrentiev Ave., 3, Novosibirsk, 630090, Russian Federation.
| | - Denis G Samsonenko
- Nikolaev Institute of Inorganic Chemistry, Russian Academy of Sciences, Siberian Branch, Acad. Lavrentiev Ave., 3, Novosibirsk, 630090, Russian Federation. and Novosibirsk State University, Pirogov str., 2, Novosibirsk, 630090, Russian Federation
| | - Danil N Dybtsev
- Nikolaev Institute of Inorganic Chemistry, Russian Academy of Sciences, Siberian Branch, Acad. Lavrentiev Ave., 3, Novosibirsk, 630090, Russian Federation. and Novosibirsk State University, Pirogov str., 2, Novosibirsk, 630090, Russian Federation
| | - Vladimir P Fedin
- Nikolaev Institute of Inorganic Chemistry, Russian Academy of Sciences, Siberian Branch, Acad. Lavrentiev Ave., 3, Novosibirsk, 630090, Russian Federation. and Novosibirsk State University, Pirogov str., 2, Novosibirsk, 630090, Russian Federation
| | - Stephen P Argent
- School of Chemistry, University of Nottingham, NG7 2RD Nottingham, UK
| | - Alexander J Blake
- School of Chemistry, University of Nottingham, NG7 2RD Nottingham, UK
| | - Martin Schröder
- Nikolaev Institute of Inorganic Chemistry, Russian Academy of Sciences, Siberian Branch, Acad. Lavrentiev Ave., 3, Novosibirsk, 630090, Russian Federation. and School of Chemistry, University of Manchester, M13 9PL Manchester, UK
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6
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Ansari MA, Mandal A, Paretzki A, Beyer K, Kaim W, Lahiri GK. Isomeric Diruthenium Complexes of a Heterocyclic and Quinonoid Bridging Ligand: Valence and Spin Alternatives for the Metal/Ligand/Metal Arrangement. Inorg Chem 2016; 55:12357-12365. [DOI: 10.1021/acs.inorgchem.6b02245] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mohd. Asif Ansari
- Department
of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Abhishek Mandal
- Department
of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Alexa Paretzki
- Institut für
Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring
55, Stuttgart D-70550, Germany
| | - Katharina Beyer
- Institut für
Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring
55, Stuttgart D-70550, Germany
| | - Wolfgang Kaim
- Institut für
Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring
55, Stuttgart D-70550, Germany
| | - Goutam Kumar Lahiri
- Department
of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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7
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Wild U, Kaifer E, Wadepohl H, Himmel HJ. Combined Oxidation, Deprotonation, and Metal Coordination of a Redox-Active Guanidine Ligand. Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201500597] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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8
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Abramov PA, Gritsan NP, Suturina EA, Bogomyakov AS, Sokolov MN. Rhenium Complex with Noninnocent Dioxolene Ligand: Combined Experimental and ab Initio Study of [(3,5-di-tert-Bu2C6H2O2)ReCl3(OPPh3)]. Inorg Chem 2015; 54:6727-35. [PMID: 26135029 DOI: 10.1021/acs.inorgchem.5b00407] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reaction of [ReOCl3(PPh3)2] with 3,5-di-tert-butyl-1,2-benzoquinone (3,5-DTBQ) in hot toluene produces a new complex [(3,5-di-tert-Bu2C6H2O2)Re(OPPh3)Cl3] (1), which was isolated and characterized by elemental analysis, IR, UV-vis spectroscopy, and cyclic voltammetry. In order to clarify the charge state of rhenium and the coordinated dioxolene ligand, X-ray experiments at 150 and 290 K were carried out. The C-O, C-C, and Re-O bond distances at both 150 and 290 K fall between those for semiquinolate (3,5-DTBSQ) and catecholate (3,5-DTBCat) forms; an empirical "metrical oxidation state" of the dioxolene ligand was estimated to be -1.5. High-level ab initio calculations (SOC-CASSCF/NEVPT2) revealed a mixed valence nature of the triplet ground state of complex 1 corresponding to a superposition of the Re(IV)-SQ and Re(V)-cat forms. In agreement with the high-level ab initio and DFT calculations, the temperature dependence of the magnetic susceptibility (5-300 K) is well described in the assumption of the triplet ground state, with the anomalously large zero-field splitting (ZFS) arising from the spin-orbit coupling. According to the ab initio calculations, all absorption bands in the visible region of the electronic absorptions spectrum are assigned to the LMCT bands, with significant contribution of the intraligand transition in the most intense band at 555 nm.
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Affiliation(s)
- Pavel A Abramov
- †Nikolayev Institute of Inorganic Chemistry, Prospekt Lavrentyeva 3, 630090 Novosibirsk, Russia.,‡Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk, Russia
| | - Nina P Gritsan
- ‡Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk, Russia.,§Voevodsky Institute of Chemical Kinetics and Combustion, Institutskaya str. 3, 630090 Novosibirsk, Russia
| | - Elizaveta A Suturina
- ‡Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk, Russia.,§Voevodsky Institute of Chemical Kinetics and Combustion, Institutskaya str. 3, 630090 Novosibirsk, Russia
| | - Artem S Bogomyakov
- ‡Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk, Russia.,∥International Tomography Center, Institutskaya str. 3a, 630090 Novosibirsk, Russia
| | - Maxim N Sokolov
- †Nikolayev Institute of Inorganic Chemistry, Prospekt Lavrentyeva 3, 630090 Novosibirsk, Russia.,‡Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk, Russia
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9
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Scattergood PA, Jesus P, Adams H, Delor M, Sazanovich IV, Burrows HD, Serpa C, Weinstein JA. Exploring excited states of Pt(II) diimine catecholates for photoinduced charge separation. Dalton Trans 2015; 44:11705-16. [PMID: 25683063 DOI: 10.1039/c4dt03466j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The intense absorption in the red part of the visible range, and the presence of a lowest charge-transfer excited state, render Platinum(II) diimine catecholates potentially promising candidates for light-driven applications. Here, we test their potential as sensitisers in dye-sensitised solar cells and apply, for the first time, the sensitive method of photoacoustic calorimetry (PAC) to determine the efficiency of electron injection in the semiconductor from a photoexcited Pt(II) complex. Pt(II) catecholates containing 2,2′-bipyridine-4,4′-di-carboxylic acid (dcbpy) have been prepared from their parent iso-propyl ester derivatives, complexes of 2,2′-bipyridine-4,4′-di-C(O)OiPr, (COOiPr)2bpy, and their photophysical and electrochemical properties studied. Modifying diimine Pt(II) catecholates with carboxylic acid functionality has allowed for the anchoring of these complexes to thin film TiO2, where steric bulk of the complexes (3,5-di(t)Bu-catechol vs. catechol) has been found to significantly influence the extent of monolayer surface coverage. Dye-sensitised solar cells using Pt(dcbpy)((t)Bu2Cat), 1a, and Pt(dcbpy)(pCat), 2a, as sensitisers, have been assembled, and photovoltaic measurements performed. The observed low, 0.02–0.07%, device efficiency of such DSSCs is attributed at least in part to the short excited state lifetime of the sensitisers, inherent to this class of complexes. The lifetime of the charge-transfer ML/LLCT excited state in Pt((COO(I)Pr)2bpy)(3,5-di-(t)Bu-catechol) was determined as 250 ps by picosecond time-resolved infrared spectroscopy, TRIR. The measured increase in device efficiency for 2a over 1a is consistent with a similar increase in the quantum yield of charge separation (where the complex acts as a donor and the semiconductor as an acceptor) determined by PAC, and is also proportional to the increased surface loading achieved with 2a. It is concluded that the relative efficiency of devices sensitised with these particular Pt(II) species is governed by the degree of surface coverage. Overall, this work demonstrates the use of Pt(diimine)(catecholate) complexes as potential photosensitizers in solar cells, and the first application of photoacoustic calorimetry to Pt(II) complexes in general.
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Affiliation(s)
- Paul A Scattergood
- Department of Chemistry, University of Sheffield, Sheffield, S3 7HF, UK.
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10
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Ziesak A, Wesp T, Hübner O, Kaifer E, Wadepohl H, Himmel HJ. Counter-ligand control of the electronic structure in dinuclear copper-tetrakisguanidine complexes. Dalton Trans 2015; 44:19111-25. [DOI: 10.1039/c5dt03270a] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Decision-making counter-ligands: a bridging redox-active ligand in a dinuclear copper complex could be either neutral (complex type [CuII-GFA-CuII]) or dicationic (complex type [CuI-GFA-CuI]), depending on the nature of the counter-ligands X.
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Affiliation(s)
- Alexandra Ziesak
- Anorganisch-Chemisches Institut
- Ruprecht-Karls Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Tobias Wesp
- Anorganisch-Chemisches Institut
- Ruprecht-Karls Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Olaf Hübner
- Anorganisch-Chemisches Institut
- Ruprecht-Karls Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut
- Ruprecht-Karls Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Hubert Wadepohl
- Anorganisch-Chemisches Institut
- Ruprecht-Karls Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Hans-Jörg Himmel
- Anorganisch-Chemisches Institut
- Ruprecht-Karls Universität Heidelberg
- 69120 Heidelberg
- Germany
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11
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Moussa J, Chamoreau LM, Degli Esposti A, Gullo MP, Barbieri A, Amouri H. Tuning Excited States of Bipyridyl Platinum(II) Chromophores with π-Bonded Catecholate Organometallic Ligands: Synthesis, Structures, TD-DFT Calculations, and Photophysical Properties. Inorg Chem 2014; 53:6624-33. [DOI: 10.1021/ic500232w] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
| | | | - Alessandra Degli Esposti
- Istituto per la Sintesi Organica e la Fotoreattività
(ISOF), Consiglio Nazionale delle Ricerche (CNR), Via Gobetti 101, 40129 Bologna BO, Italy
| | - Maria Pia Gullo
- Istituto per la Sintesi Organica e la Fotoreattività
(ISOF), Consiglio Nazionale delle Ricerche (CNR), Via Gobetti 101, 40129 Bologna BO, Italy
| | - Andrea Barbieri
- Istituto per la Sintesi Organica e la Fotoreattività
(ISOF), Consiglio Nazionale delle Ricerche (CNR), Via Gobetti 101, 40129 Bologna BO, Italy
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12
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Armendáriz-Vidales G, Hernández-Muñoz LS, González FJ, de Souza AA, de Abreu FC, Jardim GAM, da Silva EN, Goulart MOF, Frontana C. Nature of electrogenerated intermediates in nitro-substituted nor-β-lapachones: the structure of radical species during successive electron transfer in multiredox centers. J Org Chem 2014; 79:5201-8. [PMID: 24783985 DOI: 10.1021/jo500787q] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Electrochemical, spectroelectrochemical, and theoretical studies of the reduction reactions in nor-β-lapachone derivatives including a nitro redox center showed that reduction of the compounds involves the formation of several radical intermediates, including a biradical dianion resultant from the separate reduction of the quinone and nitro groups in the molecules. Theoretical descriptions of the corresponding Fukui functions f(αα)⁺ and f(ββ)⁺(r) and LUMO densities considering finite differences and frozen core approximations for describing the changes in electron and spin densities of the system allowed us to confirm these results. A description of the potential relationship with the obtained results and biological activity selectivity indexes suggests that both the formation of stable biradical dianion species and the stability of the semiquinone intermediates during further reduction are determining factors in the description of their biological activity.
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Affiliation(s)
- Georgina Armendáriz-Vidales
- Centro de Investigación y Desarrollo Tecnológico en Electroquímica , S.C., Parque Tecnológico Querétaro Sanfandila, 76703 Pedro Escobedo, Querétaro Mexico
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13
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McCormick LJ, Abrahams BF, Boughton BA, Grannas MJ, Hudson TA, Robson R. Synthesis, structure and cation-binding properties of some [4 + 4] metallocyclic MO2(2+) (M = Mo or W) derivatives of 9-phenyl-2,3,7-trihydroxyfluor-6-one. Inorg Chem 2014; 53:1721-8. [PMID: 24484205 DOI: 10.1021/ic402860r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The trianion Z(3-) obtained from 9-phenyl 2,3,7-trihydroxyfluor-6-one, ZH3, affords dioxomolybdenum and dioxotungsten derivatives which contain [4 + 4] metallocycles of composition [(MO2)4Z4](4-) (M = Mo, W) in combination with a variety of counter cations. The syntheses, structures and ESMS of the following compounds are presented: compound 1, (MePPh3)3(NBu4)[(MoO2)4Z4]; compound 2, (MePPh3)3(NBu4)[(WO2)4Z4]; compound 3, (MePPh3)4[(WO2)4Z4]; compound 4, (PPh4)2(NBu4)2[(MoO2)4Z4]; compound 5, (AsPh4)3(NBu4)[(MoO2)4Z4]; compound 6, (AsPh4)2(NBu4)2[(WO2)4Z4]; compound 7, (Ph3PNPPh3)(NBu4)3[(MoO2)4Z4]; compound 8, (Ph3PNPPh3)(NBu4)3[(WO2)4Z4]; compound 9, (NEt4)(NBu4)3[(MoO2)4Z4]. The metallocycles in all of these compounds have similar structures, with the four metal centers located at the corners of a square slightly distorted, to varying degrees, toward a rhombus and also toward a tetrahedron. Various cations are bound inside the anionic metallocycles. ESI mass spectrometry shows that the metallocycles remain intact in the gas phase, forming [(MO2)4Z4](4-), {X-[(MO2)4Z4]}(3-) and in some cases {X2-[(MO2)4Z4]}(2-) where X(+) is an organic cation.
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Affiliation(s)
- Laura J McCormick
- School of Chemistry, University of Melbourne , Victoria 3010, Australia
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14
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Ou YP, Zhang J, Xu M, Xia J, Hartl F, Yin J, Yu GA, Liu SH. Bridge-Localized HOMO-Binding Character of Divinylanthracene-Bridged Dinuclear Ruthenium Carbonyl Complexes: Spectroscopic, Spectroelectrochemical, and Computational Studies. Chem Asian J 2014; 9:1152-60. [DOI: 10.1002/asia.201301544] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Indexed: 11/11/2022]
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15
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Mandal A, Kundu T, Ehret F, Bubrin M, Mobin SM, Kaim W, Lahiri GK. Varying electronic structural forms of ruthenium complexes of non-innocent 9,10-phenanthrenequinonoid ligands. Dalton Trans 2014; 43:2473-87. [DOI: 10.1039/c3dt53104j] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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McKinnon SDJ, Patrick BO, Lever ABP, Hicks RG. Binuclear ruthenium complexes of a neutral radical bridging ligand. A new "spin" on mixed valency. Inorg Chem 2013; 52:8053-66. [PMID: 23789578 DOI: 10.1021/ic400704j] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The electronic structures of (LX)2Ru(Vd)Ru(LX)2 complexes (Vd = 1,5-diisopropyl-3-(4,6-dimethyl-2-pyrimidinyl)-6-oxoverdazyl radical; LX = acac (acetylacetonate) or hfac (hexafluoroacetylacetonate)) in multiple charge states have been investigated experimentally and computationally. The main focus was to probe the consequences of the interplay between the ruthenium ions and the redox-active verdazyl ligand for possible mixed-valent behavior. Cyclic voltammetry studies reveal one reversible reduction and one reversible oxidation process for both complexes; in addition the acac-based derivative possesses a second reversible oxidation. Analysis of a collection of experimental (X-ray structures, EPR, electronic spectra) and computational (TD-DFT (PCM)) data reveal that the ruthenium ancillary ligands (acac vs hfac) have dramatic consequences for the electronic structures of the complexes in all charge states studied. In the hfac series, the neutral complex is best regarded as a binuclear Ru(II) species bridged by a neutral radical ligand. Reduction to give the anionic complex takes place on the verdazyl ligand, whereas oxidation to the cation (a closed shell species) is shared between Vd and ruthenium. For the acac-based complexes, the neutral species is most accurately represented as a Ru(II)/Ru(III) mixed valent complex containing a bridging verdazyl anion, though some bis(Ru(II))-neutral radical character remains. The monocation complex contains a significant contribution from a "broken symmetry" singlet diradical structure, best represented as a bis-Ru(III) system with an anionic ligand, with significant spin coupling of the two Ru(III) centers via the Vd(-1) ligand (calculated J = -218 cm(-1)). The dication, a spin doublet, consists of two Ru(III) ions linked (and antiferromagnetically coupled) to the neutral radical ligand. Computed net σ- and π-back-donation, spin densities, and orbital populations are provided. Time dependent DFT is used to predict the optical spectra and assign experimental data.
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Affiliation(s)
- Stephen D J McKinnon
- Department of Chemistry, University of Victoria, P.O. Box 3065 STN CSC, Victoria, B.C. V8W 3 V6, Canada
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Veikko U, Zhang X, Peng T, Cai P, Cheng G. The synthesis and characterization of dinuclear ruthenium sensitizers and their applications in photocatalytic hydrogen production. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 105:539-44. [PMID: 23353692 DOI: 10.1016/j.saa.2012.12.061] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 12/11/2012] [Accepted: 12/13/2012] [Indexed: 05/24/2023]
Abstract
A dinuclear ruthenium(II) dye sensitizer, ([Ru(2)(bpy)(4)BL](ClO(4))(2)) referred as Compound 1, where bpy=2,2'-bipyridine, BL=2,2'-((1E,1'E)-(((E)-diazene-1,2-diyl-bis(2,1-phenylene))-bis(azanylylidene))-bis (methanylylidene)) diphenol (a bidentate bridging ligand), was designed, synthesized and characterized. The dye sensitizer was used on the photocatalytic water splitting for hydrogen (H(2)) production over TiO(2) (P25) under visible light (λ≥400 nm) irradiation using triethanolamine (TEOA) as a sacrificial electron donor. The dye sensitized-TiO(2) demonstrated a good stability and sufficient reproducibility for over 6 h. The photosensitization ability of the sensitizer was due to its conjugation system, large molecular area, TiO(2) linkage mode and the antenna effect.
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Affiliation(s)
- Uahengo Veikko
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
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Renz M, Kaupp M. Predicting the localized/delocalized character of mixed-valence diquinone radical anions. Toward the right answer for the right reason. J Phys Chem A 2012; 116:10629-37. [PMID: 23025699 DOI: 10.1021/jp308294r] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The Robin-Day class II/III mixed-valence character is established quantum-chemically for a series of mixed-valence diquinone radical anions. Particular emphasis is placed on the radical anion of tetrathiafulvalenedibenzoquinone, Q-TTF-Q, which has recently been used to evaluate constrained density functional approaches (CDFT) and new range hybrid functionals. Using a computational protocol based on hybrid functionals with 35-42% exact-exchange admixture and inclusion of solvent models during the structure optimization, it is demonstrated that a) Q-TTF-Q(•-), 1, and the related diquinone radical anions 2-4 are all delocalized class III species in the gas phase and in nonpolar solvents, in contrast to previous assumptions; b) 1,4,5,8-anthracenetetraone radical anion, 2, remains class III in polar aprotic solvents, c) systems 1, 3 and 4 become class II, providing excellent agreement between computed and experimental intervalence charge-transfer excitations, thermal electron-transfer (ET) barriers and ESR hyperfine couplings. The direct conductor-like screening model for real solvents (D-COSMO-RS) allows the inclusion of specific hydrogen-bonding effects without the computational effort of molecular dynamics simulations and provides increased ET barriers, as well as a predicted incipient symmetry breaking for 2, due to hydrogen bonding in alcohol solvents. For the first time D-COSMO-RS optimizations in solvent mixtures have been evaluated. As previous computational studies of Q-TTF-Q(•-) neglected solvent effects during structure optimizations and obtained charge localization in gas-phase optimizations by CDFT or by exaggerated exact-exchange admixtures, they provided at best the right answer for the wrong reason.
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Affiliation(s)
- Manuel Renz
- Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Sekr. C7, Straße des 17. Juni 135, 10623 Berlin, Germany
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Yao CJ, Zhong YW, Yao J. Charge Delocalization in a Cyclometalated Bisruthenium Complex Bridged by a Noninnocent 1,2,4,5-Tetra(2-pyridyl)benzene Ligand. J Am Chem Soc 2011; 133:15697-706. [DOI: 10.1021/ja205879y] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Chang-Jiang Yao
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Yu-Wu Zhong
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Jiannian Yao
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
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Kundu T, Sarkar B, Mondal TK, Mobin SM, Urbanos FA, Fiedler J, Jiménez-Aparicio R, Kaim W, Lahiri GK. Redox-rich spin-spin-coupled semiquinoneruthenium dimers with intense near-IR absorption. Inorg Chem 2011; 50:4753-63. [PMID: 21517015 DOI: 10.1021/ic102280q] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Using the [RuCl(μ-tppz)ClRu](2+) [tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine] platform for bridging two o-quinone/catecholate two-step redox systems (unsubstituted, Q(n), or 3,5- di-tert-butyl-substituted, DTBQ(n)), we have obtained the stable complexes [(Q(•-))Ru(II)Cl(μ-tppz)ClRu(II)(Q(•-))] (1) and the structurally characterized [(DTBQ(•-))Ru(II)Cl(μ-tppz)ClRu(II)(DTBQ(•-))] (2). The compounds exhibit mostly quinone-ligand-based redox activity within a narrow potential range, high-intensity near-IR absorptions (λ(max) ≈ 920 nm; ε > 50,000 M(-1) cm(-1)), and variable intra- and intermolecular spin-spin interactions. Density functional theory calculations, electron paramagnetic resonance (EPR), and spectroelectrochemical results (UV-vis-near-IR region) for three one-electron-reduction and two one-electron-oxidation processes were used to probe the electronic structures of the systems in the various accessible valence states. EPR spectroscopy of the singly charged doublet species showed semiquinone-type response for 1(+), 2(+), and 2(-), while 1 exhibits more metal based spin, a consequence of the easier reduction of Q as compared to DTBQ. Comparison with the analogous redox series involving a more basic N-phenyliminoquinone ligand reveals significant differences related to the shifted redox potentials, different space requirements, and different interactions between the metals and the quinone-type ligands. As a result, the tppz bridge is reduced here only after full reduction of the terminal quinone ligands to their catecholate states.
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Affiliation(s)
- Tanaya Kundu
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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Best J, Sazanovich IV, Adams H, Bennett RD, Davies ES, Meijer AJHM, Towrie M, Tikhomirov SA, Bouganov OV, Ward MD, Weinstein JA. Structure and ultrafast dynamics of the charge-transfer excited state and redox activity of the ground state of mono- and binuclear platinum(II) diimine catecholate and bis-catecholate complexes: a transient absorption, TRIR, DFT, and electrochemical study. Inorg Chem 2011; 49:10041-56. [PMID: 20873855 DOI: 10.1021/ic101344t] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A series of mononuclear complexes of the type [Pt(Bu(2)cat)(4,4'-R(2)-bipy)] [where Bu(2)cat is the dianion of 3,5-(t)Bu(2)-catechol and R = H, (t)Bu, or C(O)NEt(2)] and analogous dinuclear complexes based on the "back-to-back" bis-catechol ligand 3,3',4,4'-tetrahydroxybiphenyl have been studied in detail in both their ground and excited states by a range of physical methods including electrochemistry, UV/vis/near-IR, IR, and electron paramagnetic resonance spectroelectrochemistry, and time-resolved IR (TRIR) and transient absorption (TA) spectroscopy. Density functional theory calculations have been performed to support these studies, which provide a detailed picture of the ground- and excited-state electronic structures, and excited-state dynamics, of these complexes. Notable observations include the following: (i) for the first time, the lowest-energy catecholate → bipyridine (bpy) ligand-to-ligand charge-transfer (LL'CT) excited states of these chromophores have been studied by TRIR spectroscopy, showing a range of transient bands associated with the bpy radical anion and semiquinone species, and back-electron-transfer occurring in hundreds of picoseconds; (ii) strong electronic coupling between the two catecholate units in the bridging ligand of the dinuclear complexes results in a delocalized, planar (class 3) "mixed-valence" catecholate(2-)/semiquinone(•-) state formed by one-electron oxidation of the bridging ligand; (iii) in the LL'CT excited state of the dinuclear complexes, the bridging ligand is symmetrical and delocalized, whereas the bpy radical anion is localized at one terminus of the complex. This study is the first example of an investigation of excited-state behavior in platinum(II) catecholate complexes, performed with the use of picosecond TRIR and femtosecond TA spectroscopy.
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Affiliation(s)
- Jonathan Best
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK
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Das D, Mondal TK, Chowdhury AD, Weisser F, Schweinfurth D, Sarkar B, Mobin SM, Urbanos FA, Jiménez-Aparicio R, Lahiri GK. Valence and spin situations in isomeric [(bpy)Ru(Q′)2]n (Q′ = 3,5-di-tert-butyl-N-aryl-1,2-benzoquinonemonoimine). An experimental and DFT analysis. Dalton Trans 2011; 40:8377-90. [DOI: 10.1039/c1dt10609k] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Olivier C, Costuas K, Choua S, Maurel V, Turek P, Saillard JY, Touchard D, Rigaut S. “Chain-Like” Trimetallic Ruthenium Complexes with C7 Carbon-Rich Bridges: Experimental and Theoretical Investigations of Electronic Communication Tuning in Five Distinct Oxidation States. J Am Chem Soc 2010; 132:5638-51. [DOI: 10.1021/ja908948g] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Céline Olivier
- UMR 6226 CNRS−Université de Rennes 1, Sciences Chimiques de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, France, and UMR 7177 CNRS−Université de Strasbourg, Institut de Chimie, 1 rue Blaise Pascal, BP 296 R8, F-67008 Strasbourg Cedex, France
| | - Karine Costuas
- UMR 6226 CNRS−Université de Rennes 1, Sciences Chimiques de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, France, and UMR 7177 CNRS−Université de Strasbourg, Institut de Chimie, 1 rue Blaise Pascal, BP 296 R8, F-67008 Strasbourg Cedex, France
| | - Sylvie Choua
- UMR 6226 CNRS−Université de Rennes 1, Sciences Chimiques de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, France, and UMR 7177 CNRS−Université de Strasbourg, Institut de Chimie, 1 rue Blaise Pascal, BP 296 R8, F-67008 Strasbourg Cedex, France
| | - Vincent Maurel
- UMR 6226 CNRS−Université de Rennes 1, Sciences Chimiques de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, France, and UMR 7177 CNRS−Université de Strasbourg, Institut de Chimie, 1 rue Blaise Pascal, BP 296 R8, F-67008 Strasbourg Cedex, France
| | - Philippe Turek
- UMR 6226 CNRS−Université de Rennes 1, Sciences Chimiques de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, France, and UMR 7177 CNRS−Université de Strasbourg, Institut de Chimie, 1 rue Blaise Pascal, BP 296 R8, F-67008 Strasbourg Cedex, France
| | - Jean-Yves Saillard
- UMR 6226 CNRS−Université de Rennes 1, Sciences Chimiques de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, France, and UMR 7177 CNRS−Université de Strasbourg, Institut de Chimie, 1 rue Blaise Pascal, BP 296 R8, F-67008 Strasbourg Cedex, France
| | - Daniel Touchard
- UMR 6226 CNRS−Université de Rennes 1, Sciences Chimiques de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, France, and UMR 7177 CNRS−Université de Strasbourg, Institut de Chimie, 1 rue Blaise Pascal, BP 296 R8, F-67008 Strasbourg Cedex, France
| | - Stéphane Rigaut
- UMR 6226 CNRS−Université de Rennes 1, Sciences Chimiques de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, France, and UMR 7177 CNRS−Université de Strasbourg, Institut de Chimie, 1 rue Blaise Pascal, BP 296 R8, F-67008 Strasbourg Cedex, France
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Das D, Das AK, Sarkar B, Mondal TK, Mobin SM, Fiedler J, Záliš S, Urbanos FA, Jiménez-Aparicio R, Kaim W, Lahiri GK. The Semiquinone−Ruthenium Combination as a Remarkably Invariant Feature in the Redox and Substitution Series [Ru(Q)n(acac)3−n]m, n = 1−3; m = (−2), −1, 0, +1, (+2); Q = 4,6-Di-tert-butyl-N-phenyl-o-iminobenzoquinone. Inorg Chem 2009; 48:11853-64. [DOI: 10.1021/ic901900g] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Dipanwita Das
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India
| | - Atanu Kumar Das
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany
| | - Biprajit Sarkar
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany
| | - Tapan Kumar Mondal
- Department of Chemistry, Jadavpur University, Jadavpur, Kolkata-700032, India
| | - Shaikh M. Mobin
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India
| | - Jan Fiedler
- J. Heyrovský Institute of Physical Chemistry, v.v.i., Academy of Sciences of the Czech Republic, Dolejškova 3, CZ-18223 Prague, Czech Republic
| | - Stanislav Záliš
- J. Heyrovský Institute of Physical Chemistry, v.v.i., Academy of Sciences of the Czech Republic, Dolejškova 3, CZ-18223 Prague, Czech Republic
| | - Francisco A. Urbanos
- Departamento de Química Inorgánica, Facultad de Ciencias Químicas, Universidad Complutense, Ciudad Universitaria, E-28040 Madrid, Spain
| | - Reyes Jiménez-Aparicio
- Departamento de Química Inorgánica, Facultad de Ciencias Químicas, Universidad Complutense, Ciudad Universitaria, E-28040 Madrid, Spain
| | - Wolfgang Kaim
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany
| | - Goutam Kumar Lahiri
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India
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Das D, Mondal TK, Mobin SM, Lahiri GK. Sensitive Valence Structures of [(pap)2Ru(Q)]n (n = +2, +1, 0, −1, −2) with Two Different Redox Noninnocent Ligands, Q = 3,5-Di-tert-butyl-N-aryl-1,2-benzoquinonemonoimine and pap = 2-Phenylazopyridine. Inorg Chem 2009; 48:9800-10. [DOI: 10.1021/ic901343j] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Dipanwita Das
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India
| | - Tapan Kumar Mondal
- Department of Chemistry, Jadavpur University, Jadavpur, Kolkata-700032, India
| | - Shaikh M. Mobin
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India
| | - Goutam Kumar Lahiri
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India
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27
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Leong WL, Vittal JJ. Synthesis and characterization of metal complexes of Calcein Blue: Formation of monomeric, ion pair and coordination polymeric structures. Inorganica Chim Acta 2009. [DOI: 10.1016/j.ica.2008.09.049] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abrahams BF, McCormick LJ, Robson R. Crystallographic studies on a series of salts of 2,3,7-trihydroxy-9-phenyl-fluorone. J Mol Struct 2009. [DOI: 10.1016/j.molstruc.2008.12.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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29
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Kumar M, Cervantes-Lee F, Pannell KH, Shao J. Synthesis and cyclic voltammetric studies of diiron complexes, ER(2)[(eta-C(5)H(4))Fe(L(2))Me](2) (E = C, Si, Ge, Sn; R = H, alkyl; L(2) = diphosphine] and (eta-C(5)H(5))Fe(L(2))ER(2)Fc [Fc = (eta-C(5)H(4))Fe(eta-C(5)H(5))]. Organometallics 2008; 27:4739-4748. [PMID: 19718238 PMCID: PMC2710850 DOI: 10.1021/om8004004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The cyclic voltammetric studies on ER(2)[(eta(5)-C(5)H(4))Fe(L(2))Me](2) (L(2) = dppe; ER(2) = CH(2) (1a), SiMe(2) (2a), GeMe(2) (3a), SnMe(2) (4a) revealed two well resolved reversible waves [(1)E(1/2) = -0.33 V, (2)E(1/2) = -0.20 V (for 1a); (1)E(1/2) = -0.35 V, (2)E(1/2) = -0.21 V (for 2a);(1)E(1/2) = -0.36 V, (2)E(1/2) = -0.23 V (for 3a);(1)E(1/2) = -0.36 V, (2)E(1/2) = -0.22 V (for 4a)] in CH(2)Cl(2) suggesting electronic communication between two iron centers which is seen for the first time in this family of organometallic complexes. The resolution between two reversible waves increases in the order of 1a < 2a < 3a < 4a; however, coordinating solvents such as pyridine, PhCN, DMSO and DMF decreased these interactions attributable to the stabilization of cationic species formed after the first oxidation. UV/Vis spectroelectrochemistry of 1a-4a revealed two distinct absorbance patterns for both redox processes and reflected the stepwise oxidation. Homobimetallic complexes containing ferrocenyl groups, (eta(5)-C(5)H(5))Fe(L(2))ER(2)Fc [ER(2) = none, L(2) = cis-dppen (5a), ER(2) = SiMe(2), L(2) = cis-dppen (6a), dppm (6b); ER(2) = GeMe(2), L(2) = cis-dppen (7a), dppm (7b); ER(2) = Sn(t)Bu(2), L(2) = dmpe (8a); Fc = (eta(5)-C(5)H(4))Fe(eta(5)4-C(5)H(5))] were prepared and studied in terms of electrochemistry. The cyclic voltammogram of 5a exhibited two well resolved one electron reversible waves at (1)E(1/2) = -0.21 V and (2)E(1/2) = 0.58 V corresponding to oxidation of the Fe(P-P) and Fc iron atoms respectively. Other complexes in this series (6a/6b, 7a/7b, 8a) containing direct Fe-E-Fc (E = Si, Ge and Sn) bridging units were not stable under electrochemical conditions and rupture of the Fe-E bonds was observed.
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Affiliation(s)
- Mukesh Kumar
- Department of Chemistry, University of Texas at El Paso Texas, El Paso, TX. 79968-0513, USA
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Moriuchi T, Takagi Y, Hirao T. Ferrocenyl-Cappedp-Phenylenediamine as a Redox-Switching System. Eur J Inorg Chem 2008. [DOI: 10.1002/ejic.200800072] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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31
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Elsegood MRJ, Lake AJ, Elliott CL, Smith MB, Weaver GW. Late Transition Metal Complexes of a Coumarin-Functionalized Ditertiary Phosphine. PHOSPHORUS SULFUR 2008. [DOI: 10.1080/10426500701735536] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Mark R. J. Elsegood
- a Department of Chemistry , Loughborough University , Loughborough, Leics, United Kingdom
| | - Andrew J. Lake
- a Department of Chemistry , Loughborough University , Loughborough, Leics, United Kingdom
| | - Claire L. Elliott
- a Department of Chemistry , Loughborough University , Loughborough, Leics, United Kingdom
| | - Martin B. Smith
- a Department of Chemistry , Loughborough University , Loughborough, Leics, United Kingdom
| | - George W. Weaver
- a Department of Chemistry , Loughborough University , Loughborough, Leics, United Kingdom
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Olivier C, Kim B, Touchard D, Rigaut S. Redox-Active Molecular Wires Incorporating Ruthenium(II) σ-Arylacetylide Complexes for Molecular Electronics. Organometallics 2008. [DOI: 10.1021/om700779x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Céline Olivier
- UMR 6226 CNRS-Université de Rennes 1, Sciences Chimiques de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, France, and Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
| | - BongSoo Kim
- UMR 6226 CNRS-Université de Rennes 1, Sciences Chimiques de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, France, and Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
| | - Daniel Touchard
- UMR 6226 CNRS-Université de Rennes 1, Sciences Chimiques de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, France, and Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
| | - Stéphane Rigaut
- UMR 6226 CNRS-Université de Rennes 1, Sciences Chimiques de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, France, and Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
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Patra D, Pattanayak P, Pratihar JL, Chattopadhyay S. Synthesis, structure and properties of delocalized transition metal chelates: Diazoketiminato chelates of Co(III) and Pt(II). Polyhedron 2007. [DOI: 10.1016/j.poly.2007.08.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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35
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Imide-bridged diferrocene for protonation-controlled regulation of electronic communication. Tetrahedron Lett 2007. [DOI: 10.1016/j.tetlet.2007.05.095] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kaim W, Lahiri GK. Unconventional mixed-valent complexes of ruthenium and osmium. Angew Chem Int Ed Engl 2007; 46:1778-96. [PMID: 17323423 DOI: 10.1002/anie.200602737] [Citation(s) in RCA: 307] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Recent developments have helped to extend the repertoire of mixed-valent ruthenium and osmium complexes beyond conventional systems. This extension has been achieved by using sophisticated ligands and by creating more variegated coordination patterns. The strategies employed include the use of multidentate ligands (which give rise to multinuclear and chelate complexes) and the use several redox active components (non-innocent ligands and oxidation-state ambivalence). The results offer enhanced chemical insight into metal-ligand electron-transfer situations and suggest that mixed-valent materials may eventually be exploited in molecular electronics and molecular computing.
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Affiliation(s)
- Wolfgang Kaim
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70550 Stuttgart, Germany.
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38
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Kaim W, Lahiri G. Unkonventionelle gemischtvalente Komplexe des Rutheniums und Osmiums. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200602737] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Chisholm MH. Metal to metal multiple bonds in ordered assemblies. Proc Natl Acad Sci U S A 2007; 104:2563-70. [PMID: 17299047 PMCID: PMC1815223 DOI: 10.1073/pnas.0610364104] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Indexed: 11/18/2022] Open
Abstract
The synthesis and properties of metal-metal (MM) quadruply bonded compounds of molybdenum and tungsten in liquid crystalline phases are described. Covalently linked MM quadruply bonded complexes, dimers of dimers, are shown to give rise to mixed valence complexes upon oxidation and the degree of electron delocalization is shown to be correlated with the M(2)delta bridge pi interactions. Class III behavior or complete delocalization is observed to M(2) to M(2) distances of up to 14 A. When the M(2) unit is attached to oligothiophenes via a carboxylate tether, the photophysical properties of the thienyl units are greatly modified due to M(2)delta-thienyl pi conjugation and spin-orbit coupling. This leads to long-lived emissive states and electroluminescence in solid-state devices.
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Affiliation(s)
- Malcolm H Chisholm
- Newman-Wolfrom Chemical Laboratories, Ohio State University, Columbus, OH 43210, USA.
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40
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41
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Neese F, Petrenko T, Ganyushin D, Olbrich G. Advanced aspects of ab initio theoretical optical spectroscopy of transition metal complexes: Multiplets, spin-orbit coupling and resonance Raman intensities. Coord Chem Rev 2007. [DOI: 10.1016/j.ccr.2006.05.019] [Citation(s) in RCA: 253] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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42
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Adams CJ, Charmant JPH, Connelly NG, Gill M, Kantacha A, Onganusorn S, Orpen AG. Homobinuclear cyanide-bridged linkage isomers containing the redox-active unit [(µ-XY)Ru(CO)2L(o-O2C6Cl4)] (XY = CN or NC). Dalton Trans 2007:2283-94. [PMID: 17534489 DOI: 10.1039/b700648a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The salts [NEt4][Ru(CN)(CO)2L(o-O2C6Cl4)] {L=PPh3 or P(OPh)3}, which undergo one-electron oxidation at the catecholate ligand to give neutral semiquinone complexes [Ru(CN)(CO)2L(o-O2C6Cl4)], react with the dimers [{Ru(CO)2L(micro-o-O2C6Cl4)}2] {L=PPh3 or P(OPh)3} to give [NEt4][(o-O2C6Cl4)L(OC)2Ru(micro-CN)Ru(CO)2L'(o-O2C6Cl4)] {L or L'=PPh3 or P(OPh)3}. The cyanide-bridged binuclear anions are, in turn, reversibly oxidised to isolable neutral and cationic complexes [(o-O2C6Cl4)L(OC)2Ru(micro-CN)Ru(CO)2L'(o-O2C6Cl4)] and [(o-O2C6Cl4)L(OC)2Ru(micro-CN)Ru(CO)2L'(o-O2C6Cl4)]+ which contain one and two semiquinone ligands respectively. Structural studies on the redox pair [(o-O2C6Cl4)(Ph3P)(OC)2Ru(micro-CN)Ru(CO)2(PPh3)(o-O2C6Cl4)]- and [(o-O2C6Cl4)(Ph3P)(OC)2Ru(micro-CN)Ru(CO)2(PPh3)(o-O2C6Cl4)] confirm that the C-bound Ru(CO)2(o-O2C6Cl4) fragment is oxidised first. Uniquely, [(o-O2C6Cl4){(PhO)3P}(OC)2Ru(micro-CN)Ru(CO)2(PPh3)(o-O2C6Cl4)]- is oxidised first at the N-bound fragment, indicating that it is possible to control the site of electron transfer by tuning the co-ligands. Crystallisation of [(o-O2C6Cl4)(Ph3P)(OC)2Ru(micro-CN)Ru(CO)2{P(OPh)3}(o-O2C6Cl4)] resulted in the formation of an isomer in which the P(OPh)3 ligand is cis to the cyanide bridge, contrasting with the trans arrangement of the X-Ru-L fragment in all other complexes of the type RuX(CO)2L(o-O2C6Cl4).
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43
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Berkessel A, Ertürk E, Kaiser P, Klein A, Kowalczyk RM, Sarkar B. On the redox states of ruthenium porphyrin oxidation catalysts. Dalton Trans 2007:3427-34. [PMID: 17664980 DOI: 10.1039/b705078j] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tetraarylporphyrin ruthenium complexes [Ru(L)(aryl(4)Por)] (L = CO or PF(3); aryl = mesityl or 10-R'-bis-methano-octahydroanthracene-9-yl with R' = H, CF(3), OCH(3) or CH(3)) show a rich electrochemistry with at least five different stable oxidation states (including the parent state). The overall character of the redox behaviour is porphyrin-centred. However detailed spectroelectrochemical investigations using IR, UV/Vis/NIR and EPR spectroscopy (X- and K band) gave clear indication for ruthenium contributions.
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Affiliation(s)
- Albrecht Berkessel
- Universität zu Köln, Institut für Organische Chemie, Greinstrasse 4, D-50939, Köln, Germany.
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Chisholm MH, D'Acchioli JS, Hadad CM, Patmore NJ. Concerning the Electronic Coupling of MoMo Quadruple Bonds Linked by 4,4‘-Azodibenzoate and Comparison with t2g6-Ru(II) Centers by 4,4‘-Azodiphenylcyanamido Ligands. Inorg Chem 2006; 45:11035-42. [PMID: 17173463 DOI: 10.1021/ic060956w] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
From the reactions between Mo2(O2CtBu)4 and each of terephthalic acid and 4,4'-azodibenzoic acid, the compounds [Mo2(O2CtBu)3]2(mu-O2CC6H4CO2) (1) and [Mo2(O2CtBu)3]2(mu-O2CC6H4N2C6H4CO2) (2) have been made and characterized by spectroscopic and electrochemical methods. Their electronic structures have been examined by computations employing density functional theory on model compounds where HCO2 substitutes for tBuCO2. On the basis of these studies, the two Mo2 units are shown to be only weakly coupled and the mixed-valence ions 1+ and 2+ to be valence-trapped and Class II and I, respectively, on the Robin-Day classification scheme for mixed-valence compounds. These results are compared to t2g6-Ru centers linked by 1,4-dicyanamidobenzene and azo-4,4'-diphenylcyanamido bridges for which the mixed-valence ions [Ru-bridge-Ru]5+ have been previously classified as fully delocalized, Class III [Crutchley et al. Inorg. Chem. 2001, 40, 1189; Inorg. Chem. 2004, 43, 1770], and on the basis of results described herein, it is proposed that the latter complex ion is more likely a mixed-valence organic radical where the bridge is oxidized and not the Ru(2+) centers.
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Affiliation(s)
- Malcolm H Chisholm
- Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210-1185, USA
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45
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Berben LA, Faia MC, Crawford NRM, Long JR. Angle-Dependent Electronic Effects in 4,4‘-Bipyridine-Bridged Ru3 Triangle and Ru4 Square Complexes. Inorg Chem 2006; 45:6378-86. [PMID: 16878949 DOI: 10.1021/ic060570l] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Use of 1,4,7,10-tetraazacyclododecane (cyclen) as a capping ligand and 4,4'-bipyridine (4,4'-bpy) as a bridging ligand enables assembly of redox-active Ru3 triangle and Ru4 square complexes. The former is produced by reacting [(cyclen)Ru(DMSO)Cl]Cl with 4,4'-bpy in a 3:1 ethanol:water mixture to precipitate [(cyclen)3Ru3(4,4'-bpy)3]Cl6.18H2O.THF (4), whereas the latter is generated as [(cyclen)4Ru4(4,4'-bpy)4](CF3SO3)8.2CF3SO3H.5MeOH (7) by reacting (cyclen)Ru(CF3SO3)3 with 4,4'-bpy in methanol. The crystal structure of 4.11H2O reveals an equilateral triangle in which the 4,4'-bpy bridges are bowed outward, such that the pyridine rings are all forced to be perpendicular to the Ru3 triangle. Consequently, adjacent pyridine rings are essentially coplanar, and the cyclic voltammogram of [(cyclen)3Ru3(4,4'-bpy)3]6+ in acetonitrile displays three distinct one-electron oxidation events. Cyclic voltammetry measurements reveal redox processes centered at E(1/2) = 0.207, 0.342, and 0.434 V versus Cp2Fe(0/+) that are assigned to 6+/7+, 7+/8+, and 8+/9+ couples of the [(cyclen)3Ru3(4,4'-bpy)3]n+ triangle, respectively. In contrast, the structure of [(cyclen)4Ru4(4,4'-bpy)4]8+ features a regular square geometry wherein the rings of the bridging 4,4'-bpy ligands are free to rotate, leading to just one four-electron oxidation couple centered at 0.430 V. Density functional theory calculations performed on [(cyclen)3Ru3(4,4'-bpy)(3)]6+ reveal metal-based orbitals with contributions from the pi system of the bridging 4,4'-bpy ligands, providing a likely pathway for electron transfer.
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Affiliation(s)
- Louise A Berben
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
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Rigaut S, Olivier C, Costuas K, Choua S, Fadhel O, Massue J, Turek P, Saillard JY, Dixneuf PH, Touchard D. C7 and C9 Carbon-Rich Bridges in Diruthenium Systems: Synthesis, Spectroscopic, and Theoretical Investigations of Different Oxidation States. J Am Chem Soc 2006; 128:5859-76. [PMID: 16637655 DOI: 10.1021/ja0603453] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two methodologies of C-C bond formation to achieve organometallic complexes with 7 or 9 conjugated carbon atoms are described. A C7 annelated trans-[Cl(dppe)2Ru=C=C=C-CH=C(CH2)-C[triple bond]C-Ru(dppe)2Cl][X] (X = PF6, OTf) complex is obtained from the diyne trans-[Cl(dppe)2Ru-(C[triple bond]C)2-R] (R = H, SiMe3) in the presence of [FeCp2][PF6] or HOTf, and C7 or C9 complexes trans-[Cl(dppe)2Ru-(C[triple bond]C)n-C(CH3)=C(R1)-C(R2)=C=C=Ru(dppe)2Cl][X] (n = 1, 2; R1 = Me, Ph, R2 = H, Me; X = BF4, OTf) are formed in the presence of a polyyne trans-[Cl(dppe)2Ru-(C[triple bond]C)n-R] (n = 2, 3; R = H, SiMe3) with a ruthenium allenylidene trans-[Cl(dppe)2Ru=C=C=C(CH2R1)R2][X]. These reactions proceed under mild conditions and involve cumulenic intermediates [M+]=(C=)nCHR (n = 3, 5), including a hexapentaenylidene. A combination of chemical, electrochemical, spectroscopic (UV-vis, IR, NIR, EPR), and theoretical (DFT) techniques is used to show the influence of the nature and conformation of the bridge on the properties of the complexes and to give a picture of the electron delocalization in the reduced and oxidized states. These studies demonstrate that the C7 bridging ligand spanning the metal centers by almost 12 angstroms is implicated in both redox processes and serves as a molecular wire to convey the unpaired electron with no tendency for spin localization on one of the halves of the molecules. The reactivity of the C7 complexes toward protonation and deprotonation led to original bis(acetylides), vinylidene-allenylidene, or carbyne-vinylidene species such as trans-[Cl(dppe)2Ru[triple bond]C-CH=C(CH3)-CH=C(CH3)-HC=C=Ru(dppe)2Cl][BF4]3.
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Affiliation(s)
- Stéphane Rigaut
- UMR 6226 CNRS--Université de Rennes 1, Sciences Chimiques de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, France
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47
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Siri O, Taquet JP, Collin JP, Rohmer MM, Bénard M, Braunstein P. Tunable Charge Delocalization in Dinickel Quinonoid Complexes. Chemistry 2005; 11:7247-53. [PMID: 16187375 DOI: 10.1002/chem.200500283] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
When a 2,5-diamino-1,4-benzoquinonediimine C6H2(=NR)2(NHR)2 (2) is used as a bridging ligand, new dinickel(II) complexes [(acac)Ni[mu-C6H2(=NPh)4]Ni(acac)] (3a: R=Ph) and [(acac)Ni[mu-C6H2(=NCH2tBu)4]Ni(acac)] (3b: R=CH2tBu) are obtained; upon one-electron oxidation of these complexes delocalized mixed-valence compounds are formed. An X-ray diffraction study on 3b reveals equalization of the bond lengths within each of the ligand 6 systems and a lack of conjugation between them. The oxidized state in 3b+ involves both the bridging quinonoid ligand and the metal centers, with a major contribution coming from the bridging ligand. Electrochemical and spectroscopic methods were used to study the influence of the N-substituents of the tetranitrogen donor ligands 2. In this combined experimental and theoretical (DFT) study, it is also shown that the electronic structure within the dinickel system can be altered by addition of a coordinating ligand such as pyridine. The latter favors the high-spin configuration with semi-occupied metal-centered orbitals, leading to a metal-metal interaction in the mixed-valence Ni(II)-Ni(III) 3b+ system.
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Affiliation(s)
- Olivier Siri
- Laboratoire de Chimie de Coordination, UMR 7513 CNRS, Université Louis Pasteur, 4, rue Blaise Pascal, 67070 Strasbourg Cedex, France
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Benniston AC, Chapman GM, Harriman A, Rostron SA. Reversible Luminescence Switching in a Ruthenium(II) Bis(2,2‘:6‘,2‘ ‘-terpyridine)-Benzoquinone Dyad. Inorg Chem 2005; 44:4029-36. [PMID: 15907132 DOI: 10.1021/ic050059c] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An electroactive luminescent switch has been synthesized that comprises a hydroquinone-functionalized 2,2':6',2''-terpyridine ligand coordinated to a ruthenium(II) (4'-phenylethynyl-2,2':6',2''-terpyridine) fragment. The assembly is sufficiently rigid that the hydroquinone-chromophore distance is fixed. Excitation of the complex via the characteristic metal-to-ligand charge-transfer (MLCT) absorption band produces an excited triplet state in which the promoted electron is localized on the terpyridine ligand bearing the acetylenic group. The triplet lifetime in butyronitrile solution at room temperature is 46 +/- 3 ns but increases markedly at lower temperature. Oxidation of the hydroquinone to the corresponding benzoquinone switches on an electron-transfer process whereby the MLCT triplet donates an electron to the quinone. This reaction reduces the triplet lifetime to 190 +/- 12 ps and essentially extinguishes emission. The rate of electron transfer depends on temperature in line with classical Marcus theory, allowing calculation of the electronic coupling matrix element and the reorganization energy as being 22 cm(-1) and 0.84 eV, respectively. The switching behavior can be monitored using luminescence spectroelectrochemistry. The on/off level is set by temperature and increases as the temperature is lowered.
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Affiliation(s)
- Andrew C Benniston
- Molecular Photonics Laboratory, School of Natural Sciences (Chemistry), University of Newcastle, Newcastle upon Tyne NE1 7RU, United Kingdom.
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Ye S, Sarkar B, Duboc C, Fiedler J, Kaim W. The Redox Series [M(bpy)2(Q)]n+, M = Ru or Os, Q = 3,5-Di-tert-butyl-N-phenyl-1,2-benzoquinonemonoimine. Isolation and a Complete X and W Band EPR Study of the Semiquinone States (n = 1). Inorg Chem 2005; 44:2843-7. [PMID: 15819573 DOI: 10.1021/ic048407i] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The complexes [M(bpy)(2)(Q)](PF(6)) (bpy = 2,2'-bipyridyl; M = Ru, Os; Q = 3,5-di-tert-butyl-N-phenyl-1,2-benzoquinonemonoimine) were isolated and studied by X and W band EPR in a dichloromethane solution at ambient temperatures and at 4 K. For M = Ru, the (14)N hyperfine splitting confirms the Ru(II)/semiquinone formulation, although at a > 1 mT, the (99,101)Ru satellite coupling is unusually high. W band EPR allowed us to determine the relatively small g anisotropy Delta g = g(1) - g(3) = 0.0665 for the ruthenium complex. The osmium analogue exhibits a much higher difference Delta g = 0.370, which is attributed not only to the larger spin-orbit coupling constant of Os versus that of Ru but also to a higher extent of metal contribution to the singly occupied molecular orbital. The difference Delta E between the oxidation and reduction potentials of the radical complexes is larger for the ruthenium compound (Delta E = 0.87 V) than for the osmium analogue (Delta E = 0.72), confirming the difference in metal/ligand interaction. The electrochemically generated states [M(bpy)(2)(Q)](n+), n = 0, 1, 2, and 3, were also characterized using UV-vis-near-infrared spectroelectrochemistry.
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Affiliation(s)
- Shengfa Ye
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany
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