Making organometallic molecular wires via oxidative ligand coupling

Johno, Keita; Tanaka, Yuya; Koike, Takashi; Akita, Munetaka

doi:10.1039/c1dt11077b

Cited by 10 publications

(5 citation statements)

References 32 publications

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“…However, there was a doubly charged ion observed at 1249 m/2z , which displayed a characteristic Ru 2 isotope pattern that led us to suggest that the oxidation of 3 led to some oligomerization of the alkynyl radical cation complex, most likely dimerization. Oxidation of alkynyl complexes leading to oligiomerisation was demonstrated in many systems, − and the noninnocent nature of ligands in redox reactions was highlighted by one of us recently …”

Section: Results and Discussionmentioning

confidence: 99%

Coordinating Tectons: Bimetallic Complexes from Bipyridyl Terminated Group 8 Alkynyl Complexes

Koutsantonis¹,

Low

Mackenzie³

et al. 2014

Organometallics

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Bipyridyl appended ruthenium alkynyl complexes have been used to prepare a range of binuclear homometallic ruthenium and heterometallic ruthenium−rhenium complexes. The two metal centers are only weakly coupled, as evinced by IR and UV−vis−near NIR spectroelectrochemical experiments and supported by quantum chemical calculations. The alkynyl complexes of the type [Ru(C Cbpy){L n }] ({L n } = {(PPh 3 ) 2 Cp}, {(dppe)Cp*}, {Cl(dppm) 2 }) undergo reversible one-electron oxidations centered largely on the alkynyl ligands, as has been observed previously for closely related complexes. The homometallic binuclear complexes, exemplified by [Ru(C 2 bpy-κ 2 -N′N-RuClCp)(PPh 3 ) 2 Cp] undergo two essentially reversible oxidations, the first centered on the (C 2 bpy-κ 2 -N′N-RuClCp) moiety and the second on the Ru(CCbpy)(PPh 3 ) 2 Cp fragment, leading to radical cations that can be described as Class II mixed-valence complexes. The heterometallic binuclear complexes [Ru(C 2 bpy-κ 2 -N′N-ReCl(CO) 3 ){L n }] display similar behavior, with initial oxidation on the ruthenium fragment giving rise to a new optical absorption band with Re → Ru(CCbpy) charge transfer character. The heterometallic complexes also exhibit irreversible reductions associated with the Re hetereocycle moiety. ■ EXPERIMENTAL SECTIONGeneral Considerations. All reactions were performed under an atmosphere of high purity argon or nitrogen using standard Schlenk techniques. Reaction solvents either were purified and dried using an Special Issue: Organometallic Electrochemistry

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Section: Results and Discussionmentioning

confidence: 99%

Coordinating Tectons: Bimetallic Complexes from Bipyridyl Terminated Group 8 Alkynyl Complexes

Koutsantonis¹,

Low

Mackenzie³

et al. 2014

Organometallics

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“…[29] Attempts to use Stille coupling did not yield the desired products. Such oligofuran-ferrocene complexes can be an important prototype for donor-bridge-acceptor triads [30,31] using oligofurans as bridges. DiFc-1T was prepared according to the previously described procedure (using Negishi coupling), [32] and DiFc-2T was prepared using a similar procedure (Scheme 1 and see also Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

High Charge Delocalization and Conjugation in Oligofuran Molecular Wires

Gidron

Diskin‐Posner

Bendikov

2013

Chemistry A European J

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The extent of charge delocalization and of conjugation in oligofurans and oligothiophenes was studied by using mixed valence systems comprising oligofurans and oligothiophenes capped at both ends by ferrocenyl redox units. Using electrochemical, spectral, and computational tools, we find strong charge delocalization in ferrocene-capped oligofurans which was stronger than in the corresponding oligothiophene systems. Spectroscopic studies suggest that the electronic coupling integral (H(ab)) is roughly 30-50 % greater for oligofuran-bridged systems, indicating better energy matching between ferrocene units and oligofurans. The distance decay constant (damping factor), β, is similar for oligofurans (0.066 A(-1)) and oligothiophenes (0.070 A(-1)), which suggests a similar extent of delocalization in the bridge, despite the higher HOMO-LUMO gap in oligofurans. Computational studies indicate a slightly larger extent of delocalization in furan-bridged systems compared with thiophene-bridged systems, which is consistent with oligofurans being significantly more rigid and less aromatic than oligothiophenes. High charge delocalization in oligofurans, combined with the previously reported strong fluorescence, high mobility, and high rigidity of oligofuran-based materials makes them attractive candidates for organic electronic applications.

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“…Such oxi-dation-induced dimerization at the -conjugated ligands through radical-radical coupling has been reported for monoruthenium alkynyl 21 and aryl complexes. 27 The butadiynyl ligand in 2 was found to be less electron-donating, as suggested by its oxidation potential (E 1/2 = +0.05 V). 28 The spin density of [2] + , calculated by the DFT method (Figure 5), is distributed over the Ru-(C≡C-C≡C-S) 2 moiety and, notably, there are substantial local spin densities around the terminal acetylene moieties (-0.19 and 0.22).…”

Section: Letter Synlettmentioning

confidence: 97%

“…4,[21][22][23] For example, it is known that iron radical complexes of the type [Cp*Fe(dppe)(C≡C-R)] + [Cp*: 1,2,3,4,5-pentamethylcyclopentadienyl, dppe: bis(1,2-diphenylphosphino)ethane] are highly thermally stable, 24,25 whereas their ruthenium counterparts often exhibit poor thermal stability, resulting in the formation of radical-coupling products. 26,27 This difference has been ascribed to the location of the radical center: metal-centered (Fe) vs ligand-centered (Ru) (Figure 1a). The thermal instability of mononuclear ruthenium acetylide radicals has hindered their detailed structural characterization.…”

mentioning

confidence: 99%

Thermally Stable Monoruthenium Acetylide Radical Species

Tanaka,

Akita,

Yashiro

2024

Synlett

Self Cite

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Control of radical reactivity is regarded as an important concern in the fields of catalysis and materials sciences. Radical species generated from monoruthenium acetylide complexes are, in general, highly reactive, and therefore structural characterization of these species has remained elusive. In this paper, a spectroscopic and structural characterization of the cationic radical species of a monoruthenium diacetylide bearing a Ru tetraphosphine fragment, [trans-(Ar–SC≡C)2Ru(dppe)2]SbCl6 ([1]+SbCl6) [Ar: p-t-BuC6H4; dppe: 1,2-bis(diphenylphosphino)ethane], is presented. The formation of the radical species [1]+ is supported by the vis-NIR, IR, and ESR studies. Furthermore, the solid-state structure of [1]+ reveals a significant contribution of the cumulenic Ru=C=C=S resonance structure. Remarkably, the thermal stability of [1]+ results from the incorporation of the electron-donating (arylsulfanyl)ethynyl ligands and the highly sterically demanding dppe ligands as compared with a monoruthenium complex with less-bulky and less-electron-rich derivatives.

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Making organometallic molecular wires via oxidative ligand coupling

Abstract: 1e-Oxidation of heteroaryl-metal complexes, M-het-H (het-H(2) = thiophene, pyrrole, and furan) causes coupling at the heteroaryl moiety to furnish, after deprotonation, the organometallic molecular wire with the doubly elongated linker, M-het-het-M.

Cited by 10 publications

References 32 publications

Coordinating Tectons: Bimetallic Complexes from Bipyridyl Terminated Group 8 Alkynyl Complexes

Coordinating Tectons: Bimetallic Complexes from Bipyridyl Terminated Group 8 Alkynyl Complexes

High Charge Delocalization and Conjugation in Oligofuran Molecular Wires

Thermally Stable Monoruthenium Acetylide Radical Species

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