1
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Cook BJ, Lord RL, Chen C, Caulton KG. Gauging the Redox Non‐Innocence of a Highly Pi‐Acidic Bis‐Tetrazine Pincer Ligand. Eur J Inorg Chem 2019. [DOI: 10.1002/ejic.201900186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Brian J. Cook
- Department of Chemistry Indiana University 47405 Bloomington IN USA
| | - Richard L. Lord
- Department of Chemistry Grand Valley State University 49401 Allendale MI USA
| | - Chun‐Hsing Chen
- Department of Chemistry Indiana University 47405 Bloomington IN USA
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2
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Liu M, Hu J, Wang Y. Synthesis, crystal structure and MMCT of a heterobimetallic cyanide-bridged complex trans-BrRuII(dppe)2(μ-CN)(FeIIIBr3). Polyhedron 2018. [DOI: 10.1016/j.poly.2018.04.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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3
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Tripathy SK, van der Meer M, Sahoo A, Laha P, Dehury N, Plebst S, Sarkar B, Samanta K, Patra S. A dinuclear [{(p-cym)Ru(II)Cl}2(μ-bpytz˙(-))](+) complex bridged by a radical anion: synthesis, spectroelectrochemical, EPR and theoretical investigation (bpytz = 3,6-bis(3,5-dimethylpyrazolyl)1,2,4,5-tetrazine; p-cym = p-cymene). Dalton Trans 2018; 45:12532-8. [PMID: 27435992 DOI: 10.1039/c6dt01995a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The reaction of the chloro-bridged dimeric precursor [{(p-cym)Ru(II)Cl}(μ-Cl)]2 (p-cym = p-cymene) with the bridging ligand 3,6-bis(3,5-dimethylpyrazolyl)-1,2,4,5-tetrazine (bpytz) in ethanol results in the formation of the dinuclear complex [{(p-cym)Ru(II)Cl}2(μ-bpytz˙(-))](+), [1](+). The bridging tetrazine ligand is reduced to the anion radical (bpytz˙(-)) which connects the two Ru(II) centres. Compound [1](PF6) has been characterised by an array of spectroscopic and electrochemical techniques. The radical anion character has been confirmed by magnetic moment (corresponding to one electron paramagnetism) measurement, EPR spectroscopic investigation (tetrazine radical anion based EPR spectrum) as well as density functional theory based calculations. Complex [1](+) displays two successive one electron oxidation processes at 0.66 and 1.56 V versus Ag/AgCl which can be attributed to [{(p-cym)Ru(II)C}2(μ-bpytz˙(-))](+)/[{(p-cym)Ru(II)Cl}2(μ-bpytz)](2+) and [{(p-cym)Ru(II)Cl}2(μ-bpytz)](+)/[{(p-cym)Ru(III)Cl}2(μ-bpytz)](2+) processes (couples I and II), respectively. The reduction processes (couple III-couple V), which are irreversible, likely involve the successive reduction of the bridging ligand and the metal centres together with loss of the coordinated chloride ligands. UV-Vis-NIR spectroelectrochemical investigation reveals typical tetrazine radical anion containing bands for [1](+) and a strong absorption in the visible region for the oxidized form [1](2+), which can be assigned to a Ru(II) → π* (tetrazine) MLCT transition. The assignment of spectroscopic bands was confirmed by theoretical calculations.
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Affiliation(s)
- Suman Kumar Tripathy
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar - 751007, India.
| | - Margarethe van der Meer
- Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße 34-36, D-14195 Berlin, Germany.
| | - Anupam Sahoo
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar - 751007, India.
| | - Paltan Laha
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar - 751007, India.
| | - Niranjan Dehury
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar - 751007, India.
| | - Sebastian Plebst
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569, Stuttgart, Germany
| | - Biprajit Sarkar
- Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße 34-36, D-14195 Berlin, Germany.
| | - Kousik Samanta
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar - 751007, India.
| | - Srikanta Patra
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar - 751007, India.
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4
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Das A, Ghosh P, Priego JL, Jiménez-Aparicio R, Lahiri GK. Unsymmetric (μ-oxido)/(μ-pyrazolato) and Symmetric (μ-pyrazolato)2 Bridged Diosmium Frameworks: Electronic Structure and Magnetic Properties. Inorg Chem 2016; 55:8396-406. [DOI: 10.1021/acs.inorgchem.6b00898] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ankita Das
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Prabir Ghosh
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - José Luis Priego
- 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
| | - Goutam Kumar Lahiri
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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5
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Mondal P, Ehret F, Bubrin M, Das A, Mobin SM, Kaim W, Lahiri GK. A Diruthenium Complex of a “Nindigo” Ligand. Inorg Chem 2013; 52:8467-75. [DOI: 10.1021/ic400390b] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Prasenjit Mondal
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai
400076, India
| | - Fabian Ehret
- Institut
für Anorganische
Chemie, Universität Stuttgart, Pfaffenwaldring
55, D-70550 Stuttgart, Germany
| | - Martina Bubrin
- Institut
für Anorganische
Chemie, Universität Stuttgart, Pfaffenwaldring
55, D-70550 Stuttgart, Germany
| | - Amit Das
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai
400076, India
| | - Shaikh M. Mobin
- Discipline of Chemistry, School
of Basic Sciences, Indian Institute of Technology Indore, Indore 452017, India
| | - 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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6
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7
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Esteruelas MA, Fernández I, Gómez-Gallego M, Martín-Ortíz M, Molina P, Oliván M, Otón F, Sierra MA, Valencia M. Mono- and dinuclear osmium N,N'-di- and tetraphenylbipyridyls and extended bipyridyls. Synthesis, structure and electrochemistry. Dalton Trans 2013; 42:3597-608. [PMID: 23292252 DOI: 10.1039/c2dt32548a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The efficient synthesis of mono- and dinuclear Os(IV) bipyridyl complexes is reported. These compounds show a two-step oxidation process leading to notable structural changes, which are reflected in their emission properties. During the second oxidation process a tetracation with a hydride-dihydrogen structure (instead of a trihydride) is formed. This results in a significant bathochromic shift of the emission band, accompanied by a moderate increase in intensity.
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Affiliation(s)
- Miguel A Esteruelas
- Departamento de Quíımica Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea, Universidad de Zaragoza-CSIC, 50009, Zaragoza, Spain.
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8
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Brietzke T, Mickler W, Kelling A, Schilde U, Krüger H, Holdt H. Mono‐ and Dinuclear Ruthenium(II)–1,6,7,12‐Tetraazaperylene Complexes of
N
,
N′
‐Dimethyl‐2,11‐diaza[3.3](2,6)‐pyridinophane. Eur J Inorg Chem 2012. [DOI: 10.1002/ejic.201200667] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Thomas Brietzke
- Anorganische Chemie, Institut für Chemie, Universität Potsdam, Karl‐Liebknecht‐Straße 24‐25, 14476 Golm, Germany, Fax: +49‐331‐9775055, http://www.chem.uni‐potsdam.de/anorganik
| | - Wulfhard Mickler
- Anorganische Chemie, Institut für Chemie, Universität Potsdam, Karl‐Liebknecht‐Straße 24‐25, 14476 Golm, Germany, Fax: +49‐331‐9775055, http://www.chem.uni‐potsdam.de/anorganik
| | - Alexandra Kelling
- Anorganische Chemie, Institut für Chemie, Universität Potsdam, Karl‐Liebknecht‐Straße 24‐25, 14476 Golm, Germany, Fax: +49‐331‐9775055, http://www.chem.uni‐potsdam.de/anorganik
| | - Uwe Schilde
- Anorganische Chemie, Institut für Chemie, Universität Potsdam, Karl‐Liebknecht‐Straße 24‐25, 14476 Golm, Germany, Fax: +49‐331‐9775055, http://www.chem.uni‐potsdam.de/anorganik
| | - Hans‐Jörg Krüger
- Anorganische Chemie, Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin‐Schrödinger‐Straße Geb. 54, 67663 Kaiserslautern, Germany, Fax: +49‐631‐2054676, http://www.chemie.uni‐kl.de/forschung/ac/krueger
| | - Hans‐Jürgen Holdt
- Anorganische Chemie, Institut für Chemie, Universität Potsdam, Karl‐Liebknecht‐Straße 24‐25, 14476 Golm, Germany, Fax: +49‐331‐9775055, http://www.chem.uni‐potsdam.de/anorganik
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9
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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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10
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Kundu T, Sarkar B, Mondal TK, Fiedler J, Mobin SM, Kaim W, Lahiri GK. Carboxylate Tolerance of the Redox-Active Platform [Ru(μ-tppz)Ru]n, where tppz = 2,3,5,6-Tetrakis(2-pyridyl)pyrazine, in the Electron-Transfer Series [(L)ClRu(μ-tppz)RuCl(L)]n, n = 2+, +, 0, −, 2−, with 2-Picolinato, Quinaldato, and 8-Quinolinecarboxylato Ligands (L−). Inorg Chem 2010; 49:6565-74. [DOI: 10.1021/ic100500p] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Tanaya Kundu
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - 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
| | - 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
| | - Shaikh M. Mobin
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - 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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11
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Sarkar B, Frantz S, Roy S, Sieger M, Duboc C, Denninger G, Kümmerer HJ, Kaim W. High-frequency EPR and structural data as complementary information on stable radical complexes containing the semi-reduced azo function. J Mol Struct 2008. [DOI: 10.1016/j.molstruc.2008.04.048] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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12
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Ghumaan S, Sarkar B, Maji S, Puranik V, Fiedler J, Urbanos F, Jimenez-Aparicio R, Kaim W, Lahiri G. Valence-State Analysis through Spectroelectrochemistry in a Series of Quinonoid-Bridged Diruthenium Complexes [(acac)2Ru(μ-L)Ru(acac)2]n (n=+2, +1, 0, −1, −2). Chemistry 2008; 14:10816-28. [DOI: 10.1002/chem.200800976] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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13
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Double cyclometallation of bridging 3,6-bis(2-thienyl)-1,2,4,5-tetrazine in a dinuclear mesityl(dimethylsulfoxide)platinum(II) complex: Structure and properties. J Organomet Chem 2008. [DOI: 10.1016/j.jorganchem.2007.10.045] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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14
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Kavakli C, Gabrielsson A, Sieger M, Schwederski B, Niemeyer M, Kaim W. Reversible radical complex formation of an organometallic diplatinum(IV) compound. J Organomet Chem 2007. [DOI: 10.1016/j.jorganchem.2007.01.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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15
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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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16
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El-Qisairi AK. Synthesis, characterization and semiempirical calculations of mercury(II) complexes of 3,6-bis(2′-pyridyl)-1,2,4,5-tetrazine. J COORD CHEM 2007. [DOI: 10.1080/00958970601001890] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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17
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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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18
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19
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Kar S, Sarkar B, Ghumaan S, Leboschka M, Fiedler J, Kaim W, Lahiri GK. Ancillary ligand determination of the spin location in both oxidised and reduced forms of diruthenium complexes bridged by bis-bidentate 1,4-bis(2-phenolato)-1,4-diazabutadiene. Dalton Trans 2007:1934-8. [PMID: 17702173 DOI: 10.1039/b617468j] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The rare bridging mode of 1,4-bis(2-phenolato)-1,4-diazabutadiene = glyoxalbis(2-hydroxyanil) (L(2-)) is adopted in {(mu-L(2-))[Ru11(bpy)22}2+ (1(2+)), obtained as bis-perchlorate. Four well accessible redox forms of 1(n) (n = 4+, 3+, 2+, +) have been characterised by UV-VIS-NIR spectroelectrochemistry. The (3+) and (+) intermediates have also been investigated by EPR, both showing radical-type signals close to g = 2. This observation stands in stark contrast to EPR results previously obtained for the related {(mu-L)[Ru(acac)2]2(n), n = + and -, both of which exhibit metal-centred spin. In combination with the UV-VIS-NIR spectra these results suggest the preferential involvement of the multistep ligand redox system L(n-) in the electron transfer processes. The relative stabilisation of Ru11 by pi-accepting bpy is made responsible for the oxidation of the ligand L(2-) instead of the metal.
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Affiliation(s)
- Sanjib Kar
- Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai 400076, India
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20
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Ghumaan S, Lahiri GK. Tuning intermetallic electronic coupling in polyruthenium systems via molecular architecture. J CHEM SCI 2006. [DOI: 10.1007/bf02703951] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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21
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Ghumaan S, Sarkar B, Chanda N, Sieger M, Fiedler J, Kaim W, Lahiri GK. 2,2‘-Dipyridylketone (dpk) as Ancillary Acceptor and Reporter Ligand in Complexes [(dpk)(Cl)Ru(μ-tppz)Ru(Cl)(dpk)]n+ where tppz = 2,3,5,6-Tetrakis(2-pyridyl)pyrazine. Inorg Chem 2006; 45:7955-61. [PMID: 16961390 DOI: 10.1021/ic060887l] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The tppz-bridged diruthenium(II) complex [(dpk)(Cl)Ru(II)(mu-tppz)Ru(II)(Cl)(dpk)](ClO4)2, [2](ClO4)2, and mononuclear [(dpk)(Cl)Ru(II)(tppz)](ClO4), [1](ClO4) [tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine, dpk = 2,2'-dipyridylketone], have been synthesized. The 260 mV separation between successive one-electron oxidation couples in [2]2+ translates to a relatively small comproportionation constant, Kc, of 2.5 x 10(4) for the intermediate. It is shown how electrochemical data (E(ox), E(red), Kc) reflect the donor/acceptor effects of ancillary ligands L in a series of systems [(L)ClRu(mu-tppz)RuCl(L)]n, particularly the competition between L and tppz for electron density from the metal. According to EPR (g1 = 2.470, g2 = 2.195, and g3 = 1.873 at 4 K) the intermediate [2]3+ is a mixed-valent Ru(II)Ru(III) species which shows a rather narrow intervalence charge transfer (IVCT) band at 1800 nm (epsilon = 1500 M(-1) cm(-1)). The width at half-height (Deltanu(1/2)) of 700 cm(-1) of the IVCT band is much smaller than the calculated value of 3584 cm(-1), obtained by using the Hush formula Deltanu(1/2) = (2310E(op))(1/2) (E(op) = 5556 cm(-1), energy of the IVCT transition) which would be applicable to localized (Class II) mixed-valent Ru(II)Ru(III) systems. Valence delocalization in [2]3+ is supported by the uniform shift of the nu(C=O) band of the N,N'-coordinated dpk ligands from 1676 cm(-1) in the Ru(II)Ru(II) precursor to 1690 cm(-1) in the Ru(2.5)Ru(2.5) form, illustrating the use of the dpk acceptor to act as reporter ligand via the free but pi-conjugated organic carbonyl group. The apparent contradiction between the moderate value of Kc and the narrow IVCT band is being discussed considering "borderline" or "hybrid" "Class II-III" concepts of mixed-valency, as well as coordination aspects, i.e., the bis-tridentate nature of the pi-acceptor bridging ligand. Altogether, the complex ions [1]+ and [2]2+ display four and five successive reduction processes, respectively, involving both tppz- and dpk-based unoccupied pi orbitals. The one-electron reduced form [2]+ has been assigned as a tppz*- radical-anion-containing species which exhibits a free-radical-type EPR signal at 4K (g(parallel) = 2.002, g(perpendicular) = 1.994) and one moderately intense ligand-based low-energy band at 965 nm (epsilon = 1100 M(-1) cm(-1)).
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Affiliation(s)
- Sandeep Ghumaan
- Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai - 400076, India
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22
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Patra S, Sarkar B, Maji S, Fiedler J, Urbanos FA, Jimenez-Aparicio R, Kaim W, Lahiri GK. Controlling Metal–Ligand–Metal Oxidation State Combinations by Ancillary Ligand (L) Variation in the Redox Systems [L2Ru(μ-boptz)RuL2]n, boptz=3,6-bis(2-oxidophenyl)-1,2,4,5-tetrazine, and L=acetylacetonate, 2,2′-bipyridine, or 2-phenylazopyridine. Chemistry 2006; 12:489-98. [PMID: 16134203 DOI: 10.1002/chem.200500295] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The new compounds [(acac)2Ru(mu-boptz)Ru(acac)2] (1), [(bpy)2Ru(mu-boptz)Ru(bpy)2](ClO4)2 (2-(ClO4)2), and [(pap)2Ru(mu-boptz)Ru(pap)2](ClO4)2 (3-(ClO4)2) were obtained from 3,6-bis(2-hydroxyphenyl)-1,2,4,5-tetrazine (H2boptz), the crystal structure analysis of which is reported. Compound 1 contains two antiferromagnetically coupled (J = -36.7 cm(-1)) Ru(III) centers. We have investigated the role of both the donor and acceptor functions containing the boptz2- bridging ligand in combination with the electronically different ancillary ligands (donating acac-, moderately pi-accepting bpy, and strongly pi-accepting pap; acac = acetylacetonate, bpy = 2,2'-bipyridine pap = 2-phenylazopyridine) by using cyclic voltammetry, spectroelectrochemistry and electron paramagnetic resonance (EPR) spectroscopy for several in situ accessible redox states. We found that metal-ligand-metal oxidation state combinations remain invariant to ancillary ligand change in some instances; however, three isoelectronic paramagnetic cores Ru(mu-boptz)Ru showed remarkable differences. The excellent tolerance of the bpy co-ligand for both Ru(III) and Ru(II) is demonstrated by the adoption of the mixed-valent form in [L2Ru(mu-boptz)RuL2]3+, L = bpy, whereas the corresponding system with pap stabilizes the Ru(II) states to yield a phenoxyl radical ligand and the compound with L = acac- contains two Ru(III) centers connected by a tetrazine radical-anion bridge.
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Affiliation(s)
- Srikanta Patra
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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23
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Maji S, Sarkar B, Patra S, Fiedler J, Mobin SM, Puranik VG, Kaim W, Lahiri GK. Metal-Induced Reductive Ring Opening of 1,2,4,5-Tetrazines: Three Resulting Coordination Alternatives, Including the New Non-Innocent 1,2-Diiminohydrazido(2−) Bridging Ligand System. Inorg Chem 2005; 45:1316-25. [PMID: 16441144 DOI: 10.1021/ic051532p] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reaction of 3,6-diaryl-1,2,4,5-tetrazines (aryl = R = phenyl, 2-furyl or 2-thienyl) with 2 equiv of Ru(acac)2(CH3CN)2 results in reductive tetrazine ring opening to yield diruthenium complexes [(acac)2Ru(III)(dih-R(2-))Ru(III)(acac)2] bridged by the new 1,2-diiminohydrazido(2-) (dih-R(2-) = HNC(R)NNC(R)NH(2-)) ligands. rac/meso diastereoisomers could be detected and separated for the compounds with R = phenyl and 2-thienyl, all species are diamagnetic and were characterized by 1H NMR spectroscopy. Crystal structure determination of the meso isomers with R = phenyl and 2-thienyl confirmed the 1,2-diiminohydrazido formulation through long N-N (approximately 1.40 A) and short C=N(H) bonds (approximately 1.31 A), implying two bridged ruthenium(III) centers at about 4.765 A distance with strong antiferromagnetic coupling. The complexes undergo two reversible and well-separated one-electron reduction and oxidation processes, respectively. EPR Spectroscopy of the paramagnetic intermediates with comproportionation constants K(c) > 10(12) and UV-vis-NIR spectroelectrochemistry were used to identify the accessible redox states as [(acac)2Ru(II)(dih-R(2-))Ru(II)(acac)2]2-, [(acac)2Ru(II)(dih-R(*-))Ru(II)(acac)2]-, [(acac)2Ru(III)(dih-R(2-))Ru(III)(acac)2], [(acac)2Ru(III)(dih-R(*-))Ru(III)(acac)2]+, and [(acac)2Ru(III)(dih-R)Ru(III)(acac)2]2+. While the UV-vis-NIR spectroscopic response of [(acac)2Ru(dih-R)Ru(acac)2](0/-/2-) is very similar to that of [(bpy)2Ru(adc-R)Ru(bpy)2](4+/3+/2+), adc-R(2-) = 1,2-diacylhydrazido(2-), the EPR result indicating ligand-centered spin for [(acac)2Ru(II)(dih-R(*-))Ru(II)(acac)2]- despite deceptive NIR absorptions around 1400 nm reveals distinct differences in the electronic structures.
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Affiliation(s)
- Somnath Maji
- Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai-400076, India
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Klein A, Lavastre O, Fiedler J. Role of the Bridging Arylethynyl Ligand in Bi- and Trinuclear Ruthenium and Iron Complexes. Organometallics 2005. [DOI: 10.1021/om050876k] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Axel Klein
- Institut für Anorganische Chemie, Universität zu Köln, Greinstrasse 6, D-50939 Köln, Germany, Institut de Chimie CIT Rennes, UMR 6509 CNRS Université de Rennes 1, Campus de Beaulieu, F-35042 Rennes, France, and J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, CZ-18223 Prague, Czech Republic
| | - Olivier Lavastre
- Institut für Anorganische Chemie, Universität zu Köln, Greinstrasse 6, D-50939 Köln, Germany, Institut de Chimie CIT Rennes, UMR 6509 CNRS Université de Rennes 1, Campus de Beaulieu, F-35042 Rennes, France, and J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, CZ-18223 Prague, Czech Republic
| | - Jan Fiedler
- Institut für Anorganische Chemie, Universität zu Köln, Greinstrasse 6, D-50939 Köln, Germany, Institut de Chimie CIT Rennes, UMR 6509 CNRS Université de Rennes 1, Campus de Beaulieu, F-35042 Rennes, France, and J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, CZ-18223 Prague, Czech Republic
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Kar S, Sarkar B, Ghumaan S, Janardanan D, van Slageren J, Fiedler J, Puranik VG, Sunoj RB, Kaim W, Lahiri GK. 2,5-Dioxido-1,4-benzoquinonediimine (H2L2−), A Hydrogen-Bonding Noninnocent Bridging Ligand Related to Aminated Topaquinone: Different Oxidation State Distributions in Complexes [{(bpy)2Ru}2(μ-H2L)]n (n=0,+,2+,3+,4+) and [{(acac)2Ru}2(μ-H2L)]m (m=2−,−,0,+,2+). Chemistry 2005; 11:4901-11. [PMID: 15954152 DOI: 10.1002/chem.200500202] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The symmetrically dinuclear title compounds were isolated as diamagnetic [(bpy)2Ru(mu-H2L)Ru(bpy)2](ClO4)2 (1-(ClO4)2) and as paramagnetic [(acac)2Ru(mu-H2L)Ru(acac)2] (2) complexes (bpy=2,2'-bipyridine; acac- = acetylacetonate = 2,4-pentanedionato; H2L = 2,5-dioxido-1,4-benzoquinonediimine). The crystal structure of 22 H2O reveals an intricate hydrogen-bonding network: Two symmetry-related molecules 2 are closely connected through two NH(H2L2-)O(acac-) interactions, while the oxygen atoms of H2L2- of two such pairs are bridged by an (H2O)8 cluster at half-occupancy. The cluster consists of cyclic (H2O)6 arrangements with the remaining two exo-H2O molecules connecting two opposite sides of the cyclo-(H2O)6 cluster, and oxido oxygen atoms forming hydrogen bonds with the molecules of 2. Weak antiferromagnetic coupling of the two ruthenium(III) centers in 2 was established by using SQUID magnetometry and EPR spectroscopy. Geometry optimization by means of DFT calculations was carried out for 1(2+) and 2 in their singlet and triplet ground states, respectively. The nature of low-energy electronic transitions was explored by using time-dependent DFT methods. Five redox states were reversibly accessible for each of the complexes; all odd-electron intermediates exhibit comproportionation constants K(c)>10(8). UV-visible-NIR spectroelectrochemistry and EPR spectroscopy of the electrogenerated paramagnetic intermediates were used to ascertain the oxidation-state distribution. In general, the complexes 1n+ prefer the ruthenium(II) configuration with electron transfer occurring largely at the bridging ligand (mu-H2Ln-), as evident from radical-type EPR spectra for 13+ and (+. Higher metal oxidation states (iii, iv) appear to be favored by the complexes 2m; intense long-wavelength absorption bands and RuIII-type EPR signals suggest mixed-valent dimetal configurations of the paramagnetic intermediates 2+ and 2-.
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Affiliation(s)
- Sanjib Kar
- Department of Chemistry, Indian Institute of Technology, Bombay, Powai, Mumbai 400076, India
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Moorlag C, Wolf MO, Bohne C, Patrick BO. Reversible Molecular Switching of Ruthenium Bis(bipyridyl) Groups Bonded to Oligothiophenes: Effect on Electrochemical and Spectroscopic Properties. J Am Chem Soc 2005; 127:6382-93. [PMID: 15853346 DOI: 10.1021/ja043573a] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the preparation of complexes in which ruthenium(II) bis(bipyridyl) groups are coordinated to oligothiophenes via a diphenylphosphine linker and a thienyl sulfur (P,S bonding) to give [Ru(bpy)(2)PT(3)-P,S](PF(6))(2) (bpy = 2,2'-bipyridyl, PT(3) = 3'-(diphenylphosphino)-2,2':5',2' '-terthiophene), [Ru(bpy)(2)PMeT(3)-P,S](PF(6))(2) (PMeT(3) = 3'-(diphenylphosphino)-5-methyl-2,2':5',2' '-terthiophene), [Ru(bpy)(2)PMe(2)T(3)-P,S](PF(6))(2) (PMe(2)T(3) = 5,5' '-dimethyl-3'-(diphenylphosphino)-2,2':5',2' '-terthiophene), and [Ru(bpy)(2)PDo(2)T(5)-P,S](PF(6))(2) (PDo(2)T(5) = 3,3' '' '-didodecyl-3' '-diphenylphosphino-2,2':5',2' ':5' ',2' '':5' '',2' '' '-pentathiophene). These complexes react with base, resulting in the complexes [Ru(bpy)(2)PT(3)-P,C]PF(6), [Ru(bpy)(2)PMeT(3)-P,C]PF(6), [Ru(bpy)(2)PMe(2)T(3)-P,C]PF(6), and [Ru(bpy)(2)PDo(2)T(5)-P,C]PF(6), where the thienyl carbon is bonded to ruthenium (P,C bonding). The P,C complexes revert back to the P,S bonding mode by reaction with acid; therefore, metal-thienyl bonding is reversibly switchable. The effect of interaction of the metal groups in the different bonding modes with the thienyl backbone is reflected by changes in alignment of the thienyl rings in the solid-state structures of the complexes, the redox potentials, and the pi --> pi transitions in solution. Methyl substituents attached to the terthiophene groups allow observation of the effect of these substituents on the conformational and electronic properties and aid in assignments of the electrochemical data. The PT(n)() ligands bound in P,S and P,C bonding modes also alter the electrochemical and spectroscopic properties of the ruthenium bis(bipyridyl) group. Both bonding modes result in quenching of the oligothiophene luminescence. Weak, short-lived Ru --> bipyridyl MLCT-based luminescence is observed for [Ru(bpy)(2)PDo(2)T(5)-P,S](PF(6))(2), [Ru(bpy)(2)PT(3)-P,C]PF(6), [Ru(bpy)(2)PMeT(3)-P,C]PF(6), and [Ru(bpy)(2)PMe(2)T(3)-P,C]PF(6), and no emission is observed for the alternate bonding mode of each complex.
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Affiliation(s)
- Carolyn Moorlag
- Department of Chemistry, The University of British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada
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Ghumaan S, Sarkar B, Patra S, Parimal K, van Slageren J, Fiedler J, Kaim W, Lahiri GK. 3,6-Bis(2′-pyridyl)pyridazine (L) and its deprotonated form (L − H+)−as ligands for {(acac)2Run+} or {(bpy)2Rum+}: investigation of mixed valency in [{(acac)2Ru}2(μ-L − H+)]0and [{(bpy)2Ru}2(μ-L − H+)]4+by spectroelectrochemistry and EPR. Dalton Trans 2005:706-12. [PMID: 15702181 DOI: 10.1039/b417530a] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Crystallographically characterised 3,6-bis(2'-pyridyl)pyridazine (L) forms complexes with {(acac)2Ru} or {(bpy)2Ru2+}via one pyridyl-N/pyridazyl-N chelate site in mononuclear Ru(II) complexes (acac)2Ru(L), 1, and [(bpy)2Ru(L)](ClO4)2, [3](ClO4)2. Coordination of a second metal complex fragment is accompanied by deprotonation at the pyridazyl-C5 carbon {L --> (L - H+)-} to yield cyclometallated, asymmetrically bridged dinuclear complexes [(acac)2Ru(III)(mu-L - H+)Ru(III)(acac)2](ClO4), [2](ClO4), and [(bpy)2Ru(II)(mu-L - H+)Ru(II)(bpy)2](ClO4)3, [4](ClO4)3. The different electronic characteristics of the co-ligands, sigma donating acac- and pi accepting bpy, cause a wide variation in metal redox potentials which facilitates the isolation of the diruthenium(III) form in [2](ClO4) with antiferromagnetically coupled Ru(III) centres (J = -11.5 cm(-1)) and of a luminescent diruthenium(II) species in [4](ClO4)3. The electrogenerated mixed-valent Ru(II)Ru(III) states 2 and [4]4+ with comproportionation constants Kc > 10(8) are assumed to be localised with the Ru(III) ion bonded via the negatively charged pyridyl-N/pyridazyl-C5 chelate site of the bridging (L - H+)- ligand. In spectroelectrochemical experiments they show similar intervalence charge transfer bands of moderate intensity around 1300 nm and comparable g anisotropies (g1-g3 approximatly 0.5) in the EPR spectra. However, the individual g tensor components are distinctly higher for the pi acceptor ligated system [4]4+, signifying stabilised metal d orbitals.
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Affiliation(s)
- Sandeep Ghumaan
- Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai, 400076, India
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Tetrazine derived mononuclear RuII(acac)2(L) (1), [RuII(bpy)2(L)](ClO4)2 (2) and [RuII(bpy)(L)2](ClO4)2 (3) (L=3-amino-6-(3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine, acac=acetylacetonate, bpy=2,2′-bipyridine): syntheses, structures, spectra and redox properties. Polyhedron 2005. [DOI: 10.1016/j.poly.2004.11.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Patra S, Sarkar B, Ghumaan S, Patil MP, Mobin SM, Sunoj RB, Kaim W, Lahiri GK. Isomeric ruthenium terpyridine complexes [Ru(trpy)(L)Cl]n+ containing the unsymmetrically bidentate acceptor L = 3-amino-6-(3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine. Synthesis, structures, electrochemistry, spectroscopy and DFT calculations. Dalton Trans 2005:1188-94. [PMID: 15782253 DOI: 10.1039/b500152h] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The isomeric title complexes were obtained in almost equimolar ratio from the reaction of Ru(trpy)Cl3 and L. Crystal structure analyses of the perchlorate hemihydrates, electrochemical and spectroscopic (NMR, UV/VIS, EPR) studies, supported by DFT calculations, reveal distinct differences between the isomeric redox series [1]n+(tetrazine-Nt trans to Cl) and [2]n+(pyrazolyl-Np trans to Cl; n= 0, 1, 2). The latter system with the pi acceptors trpy and tetrazine in the equatorial plane and the pyrazolyl and chloride donors in the axial positions exhibits facilitated oxidation, lower energy MLCT transitions, more balanced chelate coordination, and a higher g anisotropy in the oxidised (RuIII) state. According to partially resolved EPR spectra of one-electron reduced neutral compounds and they have the unpaired electron predominantly in the tetrazine ring of L.
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Affiliation(s)
- Srikanta Patra
- Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai, 400076, India
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Patra S, Sarkar B, Ghumaan S, Fiedler J, Kaim W, Lahiri GK. Isovalent and Mixed-Valent Diruthenium Complexes [(acac)2RuII(μ-bpytz)RuII(acac)2] and [(acac)2RuII(μ-bpytz)RuIII(acac)2](ClO4) (acac = Acetylacetonate and bpytz = 3,6-Bis(3,5-dimethylpyrazolyl)-1,2,4,5-tetrazine): Synthesis, Spectroelectrochemical, and EPR Investigation. Inorg Chem 2004; 43:6108-13. [PMID: 15360263 DOI: 10.1021/ic049346r] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The title compounds involving the structurally characterized bridging ligand bpytz were characterized, showing very strong electrochemical stabilization of the mixed-valent RuIIRuIII state (Kc = 10(13.9)) but no detectable (epsilon < 20 M(-1) cm(-1)) intervalence charge-transfer band in the infrared region. In situ reduction of the neutral precursor produces a diruthenium(II) complex of the bpytz radical anion according to EPR spectroscopy, whereas oxidation of the mixed-valent form leads to a diruthenium(III) species.
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Affiliation(s)
- Srikanta Patra
- Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai-400076, India
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Patra S, Sarkar B, Ghumaan S, Fiedler J, Kaim W, Lahiri GK. The triruthenium complex [{(acac)2RuII}3(L)] containing a conjugated diquinoxaline[2,3-a:2′,3′-c]phenazine (L) bridge and acetylacetonate (acac) as ancillary ligands. Synthesis, spectroelectrochemical and EPR investigation. Dalton Trans 2004:754-8. [PMID: 15252496 DOI: 10.1039/b316007f] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The compound [[(acac)2Ru]3(L)] (1) undergoes three well-separated one-electron oxidation and reduction processes. The EPR results indicate electron removal from the ruthenium(II) centres on oxidation and the occupation of a largely L-based molecular orbital on reduction. In spite of well-separated (DeltaE > or = 340 mV) oxidation no obvious intervalence charge transfer bands were detected in the Vis, NIR or IR regions, suggesting very weak electronic coupling between the metal centres in the mixed-valent intermediates 1+ and 1(2+). The separated (DeltaE > or = 540 mV) stepwise reduction produces weak near-infrared features associated with partially occupied pi* orbitals of L, the unusually high g anisotropy in the EPR spectrum of 1- is attributed to the occupation of a degenerate MO by the unpaired electron.
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Affiliation(s)
- Srikanta Patra
- Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai
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