Dreispinsystem mit neuer Wendung: ein Bis(semichinonato)kupfer‐Komplex mit nichtplanarer Konfiguration am Kupfer(<scp>II</scp>)‐Zentrum

Ye, Shengfa; Sarkar, Biprajit; Lissner, Falk; Schleid, Thomas; Slageren, Joris van; Fiedler, Jan; Kaim, Wolfgang

doi:10.1002/ange.200462339

Cited by 39 publications

(21 citation statements)

References 24 publications

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“…This interpretation implies that the reduction of the complex involves an oxidation of the bridging ligand with intramolecular electron transfer compensating for the seemingly paradoxical effect. Similar phenomena have been observed before in dioxolene/metal and TCNX/metal chemistry. , On the other hand, one-electron oxidation leads to metal-centered spin, either in a mixed-valent (dih-R 2- )Ru III Ru IV situation or in the three-spin system Ru III (dih-R •- )Ru III with dominant antiferromagnetic coupling between the radical ligand and one of the two ruthenium(III) centers 6 EPR Spectra of 1a - (top) and 1a + (bottom) in CH 3 CN/0.1 M Bu 4 NPF 6 at 110 K. …”

Section: Resultssupporting

confidence: 72%

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

et al. 2005

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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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Section: Resultssupporting

confidence: 72%

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

et al. 2005

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“…This spectral behavior and the absence of detectable absorption intensity in the NIR region in 1 - (Figure a) are less compatible with a Ru III /Ru II mixed-valent formulation, which would be expected to have an intervalence charge transfer (IVCT) band in the NIR region . As a consequence, we favor a 1,4-diazabutadiene (α-diimine) centered reduction of the bridging ligand (see Schemes and ), in agreement with the π*(gbha 2- ) as LUMO; radical anions and dianions of free and, especially, coordinated 1,4-diazabutadienes have been well-established for more than 30 years. 13a, The EPR results obtained at 110 K for the intermediate are in agreement with an up/down/up three-spin formulation of {(μ-gbha •3- )[Ru III (acac) 2 ] 2 } - . Antiferromagnetic coupling between one Ru III ion and the ligand radical leaves one S = 1 / 2 metal center spin remaining, leading again to a Ru III -type EPR spectrum with g 1 = 2.27, g 2 = 2.21, and g 3 = 1.73 (Figure b).…”

Section: Resultsmentioning

confidence: 59%

A New Coordination Mode of the Photometric Reagent Glyoxalbis(2-hydroxyanil) (H₂gbha): Bis-Bidentate Bridging by gbha²^-in the Redox Series {(μ-gbha)[Ru(acac)₂]₂}ⁿ(n= −2, −1, 0, +1, +2), Including a Radical-Bridged Diruthenium(III) and a Ru^III/Ru^IVIntermediate

et al. 2005

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The bis-bidentate bridging function of gbha2- with N,O-/N,O- coordination was observed for the first time in the complex (mu-gbha)[Ru(III)(acac)2]2 (1). Density functional theory calculations of 1 yield a triplet ground state with a large (deltaE > 6000 cm(-1)) singlet-triplet gap. Intermolecular antiferromagnetic coupling was observed (J approximately -5.3 cm(-1)) for the solid. Complex 1 undergoes two one-electron reduction and two one-electron oxidation steps; the five redox forms [(mu-gbha)[Ru(acac)2]2]n (n = -2, -1, 0, +1, +2) were characterized by UV-vis-NIR spectroelectrochemistry (NIR = near infrared). The paramagnetic intermediates were also investigated by electron paramagnetic resonance (EPR) spectroscopy. The monoanion with a comproportionation constant K(c) of 2.7 x 10(8) does not exhibit an NIR band for a Ru(III)/Ru(II) mixed-valent situation; it is best described as a 1,4-diazabutadiene radical anion containing ligand gbha*3-, which binds two ruthenium(III) centers. A Ru(III)-type EPR spectrum with g1 = 2.27, g2 = 2.21, and g3 = 1.73 is observed as a result of antiferromagnetic coupling between one Ru(III) and the ligand radical. The EPR-active monocation (K(c) = 1.7 x 10(6)) exhibits a broad (deltanu(1/2) = 2600 cm(-1)) intervalence charge-transfer band at 1800 nm, indicating a valence-averaged (Ru3.5)2 formulation (class III) with a tendency toward class II (borderline situation).

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“…In contrast to the coplanar systems (Q • – )Cu II (Q • – ), with dominant antiferromagnetic interaction between the two coplanar radical ligands and a resulting metal‐based spin the twisted complex 1b shows ligand‐centered spin, corresponding to a spin up‐down‐up situation of a three‐spin system . EPR investigations of the selenium analogue 1a at standard X‐band frequency (9.5 GHz) and at high frequency (350 GHz) (Figure ) reveal that the twisted 1a behaves similarly: The g components are marginally split and rather close to the free electron value of 2.0023, which is incompatible with copper‐based spin , , . Compound 1a is EPR silent at room temperature in fluid solution, probably due to increasing occupation of the S = 3/2 excited state of the three‐spin system.…”

Section: Resultsmentioning

confidence: 98%

“…Although the partially resolved hyperfine structure in the X‐band spectrum could not be fully analyzed, the occurrence of 14 N hyperfine coupling is typical for iminosemiquinone ligands. [4a], …”

Section: Resultsmentioning

confidence: 99%

Probing the Intramolecular Metal‐Selenoether Interaction in a Bis(iminosemiquinone)copper(II) Compound

Bubrin

Paretzki

Hübner

et al. 2017

Zeitschrift anorg allge chemie

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Abstract. The selenoether compound [Cu(Q SeMe ) 2 ] [H 2 Q SeMe = 4,6-di-tert-butyl-2-(2-methylselenophenyl)aminophenol] exhibits solvatedependent NCuO/OCuN twisting (24°and 33°) and very weak copperchalcogen interactions (3.30-3.55 Å) in the crystal. Structural studies as well as EPR and magnetic measurements confirm a bis(iminosemiquinone)copper(II) configuration with one ligand-based spin in the S = ½ ground state. A spin up-down-up sequence is thus inferred

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Dreispinsystem mit neuer Wendung: ein Bis(semichinonato)kupfer‐Komplex mit nichtplanarer Konfiguration am Kupfer(II)‐Zentrum

Cited by 39 publications

References 24 publications

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

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

A New Coordination Mode of the Photometric Reagent Glyoxalbis(2-hydroxyanil) (H₂gbha): Bis-Bidentate Bridging by gbha²^-in the Redox Series {(μ-gbha)[Ru(acac)₂]₂}ⁿ(n= −2, −1, 0, +1, +2), Including a Radical-Bridged Diruthenium(III) and a Ru^III/Ru^IVIntermediate

Probing the Intramolecular Metal‐Selenoether Interaction in a Bis(iminosemiquinone)copper(II) Compound

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Dreispinsystem mit neuer Wendung: ein Bis(semichinonato)kupfer‐Komplex mit nichtplanarer Konfiguration am Kupfer(II)‐Zentrum

Cited by 39 publications

References 24 publications

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

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

A New Coordination Mode of the Photometric Reagent Glyoxalbis(2-hydroxyanil) (H2gbha): Bis-Bidentate Bridging by gbha2-in the Redox Series {(μ-gbha)[Ru(acac)2]2}n(n= −2, −1, 0, +1, +2), Including a Radical-Bridged Diruthenium(III) and a RuIII/RuIVIntermediate

Probing the Intramolecular Metal‐Selenoether Interaction in a Bis(iminosemiquinone)copper(II) Compound

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A New Coordination Mode of the Photometric Reagent Glyoxalbis(2-hydroxyanil) (H₂gbha): Bis-Bidentate Bridging by gbha²^-in the Redox Series {(μ-gbha)[Ru(acac)₂]₂}ⁿ(n= −2, −1, 0, +1, +2), Including a Radical-Bridged Diruthenium(III) and a Ru^III/Ru^IVIntermediate