Diacetonitrilebis(β-diketonato)ruthenium(II) Complexes. Their Preparation and Use as Intermediates for the Synthesis of Mixed-ligand β-Diketonato Ruthenium(III) Complexes

Coordination compounds [Ru(acac)(2)(Q)] (acac=acetylacetonate; Q=o-benzoquinone) were prepared as complexes 1 (Q=o-benzoquinone), 2 (Q=3-methoxy-o-benzoquinone), 3 (Q=4-methyl-o-benzoquinone), and 4 (Q=3,5-di-tert-butyl-o-benzoquinone). The structures of 1 and 2 were determined to reveal a Ru(III)/o-benzosemiquinone formulation, supported by analysis of experimental data (spectroscopy, magnetism of 1) and by DFT calculations. The S=1 ground state calculated for 1 stands in contrast to the spin-paired analogues with arylimino-o-benzosemiquinonato and diimino-o-benzoquinone ligands. The close contacts of about 5.3 Å possible between semiquinone O atoms of different molecules in the crystal allow for intermolecular spin-spin interactions and an overall complex magnetic behavior. One quasireversible oxidation and two reversible one-electron reductions yielded the corresponding molecular ions, which were characterized by UV-visible-NIR and EPR spectroelectrochemistry in terms of [Ru(III)(acac)(2)(Q(0))](+) , [Ru(III)(acac)(2)(Q(2-))](-), and [Ru(II)(acac)(2)(Q(2-))](2-) descriptions in agreement with DFT results. The use of acceptor-substituted 1,2-dioxolenes resulted in the isolation of ionic species Na[Ru(acac)(2)(Q)] (Na(5); Q=4-chloro-o-benzoquinone) and Na(6) (Q=4-nitro-o-benzoquinone), which were similarly investigated as compounds 1-4. Magnetic susceptibility and EPR results confirm an S=1/2 ground state based on ruthenium(III). The combined studies reveal a remarkable substituent sensitivity, and in comparison to recently analyzed Ru(acac)(2) complexes with o-benzoquinone monoimine and diimine ligands, the all-O-donor-containing new systems are distinguished by a qualitatively different metal-ligand interaction based on closer intermolecular radical-radical contacts and on weaker intramolecular dπ-π* interactions.

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“…[b] [26] was prepared according to the reported procedure. Other chemicals and solvents were of reagent grade and used as received.…”

Section: Resultsmentioning

confidence: 99%

Bis(acetylacetonato)ruthenium Complexes of Noninnocent 1,2‐Dioxolene Ligands: Qualitatively Different Bonding in Relation to Monoimino and Diimino Analogues

Das

Sarkar

Kumbhakar

et al. 2011

Chemistry A European J

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“…A C H T U N G T R E N N U N G (CH 3 CN) 2 ] was prepared according to the reported procedure. [47] The ligands 2,5-dihydroxy-1,4-benzoquinone (H 2 L1), 2,5-dihydroxy-3,6-dichloro-1,4-benzoquinone (H 2 L2), UV/Vis/NIR spectroelectrochemical studies were performed in CH 3 CN/ 0.1 m Bu 4 NPF 6 at 298 K using an optically transparent thin-layer electrode (OTTLE) cell [48] mounted in the sample compartment of a J&M Tidas spectrophotometer. FTIR spectra were taken on a Nicolet spectrophotometer with samples prepared as KBr pellets.…”

Section: Resultsmentioning

confidence: 99%

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)

Ghumaan

Sarkar

Maji

et al. 2008

Chemistry A European J

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The quinonoid ligand-bridged diruthenium compounds [(acac)(2)Ru(mu-L(2-))Ru(acac)(2)] (acac(-)=acetylacetonato=2,4-pentanedionato; L(2-)=2,5-dioxido-1,4-benzoquinone, 1; 3,6-dichloro-2,5-dioxido-1,4-benzoquinone, 2; 5,8-dioxido-1,4-naphthoquinone, 3; 2,3-dichloro-5,8-dioxido-1,4-naphthoquinone, 4; 1,5-dioxido-9,10-anthraquinone, 5; and 1,5-diimido-9,10-anthraquinone, 6) were prepared and characterized analytically. The crystal structure analysis of 5 in the rac configuration reveals two tris(2,4-pentanedionato)ruthenium moieties with an extended anthracenedione-derived bis(ketoenolate) pi-conjugated bridging ligand. The weakly antiferromagnetically coupled {Ru(III)(mu-L(2-))Ru(III)} configuration in 1-6 exhibits complicated overall magnetic and EPR responses. The simultaneous presence of highly redox-active quinonoid-bridging ligands and of two ruthenium centers capable of adopting the oxidation states +2, +3, and +4 creates a large variety of possible oxidation state combinations. Accordingly, the complexes 1-6 exhibit two reversible one-electron oxidation steps and at least two reversible reduction processes. Shifts to positive potentials were observed on introduction of Cl substituents (1-->2, 3-->4) or through replacement of NH by O (6-->5). The ligand-to-metal charge transfer (LMCT) absorptions in the visible region of the neutral molecules become more intense and shifted to lower energies on stepwise reduction with two electrons. On oxidation, the para-substituted systems 1-4 exhibit monocation intermediates with intervalence charge transfer (IVCT) transitions of Ru(III)Ru(IV) mixed-valent species. In contrast, the differently substituted systems 5 and 6 show no such near infrared (NIR) absorption. While the first reduction steps are thus assigned to largely ligand-centered processes, the oxidation appears to involve metal-ligand delocalized molecular orbitals with variable degrees of mixing.

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“…[19] Indigo (H 2 L) was purchased from Sigma-Aldrich. All other chemicals and reagents were of reagent grade and used without further purification.…”

Section: Experimental Section Materialsmentioning

confidence: 99%

Isomeric Diruthenium Complexes Bridged by Deprotonated Indigo in cis and trans Configuration

Chatterjee

Ghosh

Beyer

et al. 2017

Chemistry An Asian Journal

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Abstract:The doublyd eprotonated form L 2À of indigo = H 2 L can bind two [Ru(acac) 2 ]c omplex fragments in the cis (1) and trans configuration (2), as evidenced from crystal structure analysis. While the latter type of N,O;N ' ,O ' coordination has been observed earlier,f or example, with [Ru(bpy) 2 ] 2 + , leading to two equivalent six-membered ring chelates, the cis arrangementi n1 is observed here fort he first time in a dinuclear complex, producing one five-membered ring chelate with N,N ' coordination and one seven-membered chelate with O,O ' coordination.T he different structures of the isomersr esult in differing electrochemical and spectroelectrochemical (EPR, UV-Vis-NIR) responses for variousa ccessible charges tates 1 n and 2 n , n = -, 0, + ,2+ .T he associated electronic structures were analyzed by DFT( structures, spin density) and TD-DFT calculations (electronic transitions),r evealing mainly metal-based reduction but largely indigo ligand-based oxidation of both neutralprecursors.

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Diacetonitrilebis(β-diketonato)ruthenium(II) Complexes. Their Preparation and Use as Intermediates for the Synthesis of Mixed-ligand β-Diketonato Ruthenium(III) Complexes

Cited by 110 publications

References 3 publications

Bis(acetylacetonato)ruthenium Complexes of Noninnocent 1,2‐Dioxolene Ligands: Qualitatively Different Bonding in Relation to Monoimino and Diimino Analogues

Bis(acetylacetonato)ruthenium Complexes of Noninnocent 1,2‐Dioxolene Ligands: Qualitatively Different Bonding in Relation to Monoimino and Diimino Analogues

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)

Isomeric Diruthenium Complexes Bridged by Deprotonated Indigo in cis and trans Configuration

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Diacetonitrilebis(β-diketonato)ruthenium(II) Complexes. Their Preparation and Use as Intermediates for the Synthesis of Mixed-ligand β-Diketonato Ruthenium(III) Complexes

Cited by 110 publications

References 3 publications

Bis(acetylacetonato)ruthenium Complexes of Noninnocent 1,2‐Dioxolene Ligands: Qualitatively Different Bonding in Relation to Monoimino and Diimino Analogues

Bis(acetylacetonato)ruthenium Complexes of Noninnocent 1,2‐Dioxolene Ligands: Qualitatively Different Bonding in Relation to Monoimino and Diimino Analogues

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)

Isomeric Diruthenium Complexes Bridged by Deprotonated Indigo in cis and trans Configuration

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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)