Where’s the Spin? A DFT Study of Mixed-Valence Cyanide-Bridged Ruthenium Polypyridines

Pieslinger, German E.; Cadranel, Alejandro; Baraldo, Luis M.

doi:10.21577/0103-5053.20200135

Cited by 4 publications

(6 citation statements)

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“…To determine the nature of the electronic transition, the TDDFT calculations for 1 n + and 2 n + ( n = 3, 4) were done at the B3LYP level. ,,− The calculated result of 1 3+ shows an absorption band in the NIR area at 9354 cm –1 , which corresponds to the observed absorption band at 11 119 cm –1 in the NIR region. This band is mainly attributed to the neighboring Ru II → Ru III electron transfer transition and mainly originates from the molecular orbital HOMO – 3 (339β) → LUMO (343β) and HOMO – 1 (341β) → LUMO (343β), respectively (Figure and Table S6).…”

Section: Results and Discussionmentioning

confidence: 99%

Influence of the CN Orientation on the Degree of Electron Delocalization of Ru–Ru–Ru Mixed-Valent Complexes

Liu

et al. 2022

Inorg. Chem.

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Investigations on mixed-valent complexes in the Class II/ Class III frontier have been a particularly interesting issue due to their special electron delocalization. In this work, a pair of cyanidometal-/ isocyanidometal-bridged Ru−Ru−Ru compounds, cis-[Cp(dppe)Ru− B−Ru(dppe)Cp] 2+ (B = NCRu(bpy) 2 CN, 1 2+ ; B = CNRu(bpy) 2 NC, 2 2+ ; Cp = 1,3-cyclopentadienyl, dppe = 1,2-bis(diphenlyphosphine)ethane, bpy = 2,2′-bipyridine), and one-electron oxidized 1 3+ and 2 3+ were synthesized and well characterized. For the two-electron oxidized 1 4+ and 2 4+ , their Fourier transform infrared (FTIR) and UV−vis−NIR spectra were investigated by employing spectroelectrochemical methods. The time-dependent density-functional theory (TDDFT) calculations and the experimental results indicate that the one-/two-electron oxidized mixed-valent compounds belong to Class II−III systems.

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Section: Results and Discussionmentioning

confidence: 99%

Influence of the CN Orientation on the Degree of Electron Delocalization of Ru–Ru–Ru Mixed-Valent Complexes

Liu

et al. 2022

Inorg. Chem.

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“…As observed for related mixed-valence cyanide-bridged diruthenium polypyridines the calculated energy for the IVCT transition is lower than the observed one, which is indicative of a DFT overestimation of the delocalization compared to the experimental one. [15] This overestimation is also expressed in the higher energy calculated for the MLCT transition, as the calculations assigns a larger Ru(III) character to {Ru(tpy)(bpy)} fragment than what is observed experimentally. For the Ru II Ru III OH instead, the (TD)DFT calculation results in a mainly localized configuration (Figure S4) that reproduces well the observed spectroscopy (Figure 4).…”

Section: Vis-nir Spectroscopymentioning

confidence: 94%

“…In our experience, the use of larger basis sets, does not lead to improved results for cyanide-bridge ruthenium polypyridine systems. [15]…”

Section: Methodsmentioning

confidence: 99%

“…(TD)DFT calculations (TD)DFT calculations have shown to be a very useful tool to understand the spectroscopy of RuÀ Ru cyanide bridged complexes in different oxidation states. [8][9][10]14,15] Figure 4 shows that (TD)DFT calculations indicate that the unpaired electron in complex Ru II Ru III OH 2 is substantially delocalized between both Ru ions through the interaction promoted by the cyanide bridge (Figure S4). As observed for related mixed-valence cyanide-bridged diruthenium polypyridines the calculated energy for the IVCT transition is lower than the observed one, which is indicative of a DFT overestimation of the delocalization compared to the experimental one.…”

Section: Vis-nir Spectroscopymentioning

confidence: 99%

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A Strongly Coupled Biruthenium Complex as Catalyst for the Water Oxidation Reaction

et al. 2021

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Dedicated to Prof. José A. Olabe on occasion of his 80th birthdayThe catalytic activity towards water oxidation of a strongly coupled bimetallic ruthenium complex, trans-[Ru(tpy)(bpy)(μ-CN)Ru(py) 4 (OH 2 )] 3 + (RuIIRuIIOH2), where tpy = 2,2':6',2''-terpyridine, bpy = 2,2'-bipyridine and py = pyridine are presented. At pH 1 the first two oxidation reactions are centred at the aquo fragment and result in the Ru II Ru III OH 2 and Ru II Ru IV O redox states as confirmed by its spectroscopy and DFT calculations. Oxidation by an additional electron is followed by an irreversible step and a catalytic wave associated with the water oxidation reaction. At pH 1 the reaction with an excess of Ce(IV) results in the generation of an stoichiometric amount of oxygen based on molar amounts of the added Ce(IV). The dominant species during the catalytic cycle is the three-electron oxidized product, Ru III Ru IV O. The reduction of the concentration of Ce(IV) monitored at 370 nm follow the rate equation, À d[Ce(IV)]/dt = k ox [Ce(IV)][Ru II Ru II OH 2 ] with a k ox = 82 � 3 M À 1 s À 1 at T = 298 K. The Ru III Ru IV O species is not stable and reacts to give Ru II Ru IV O.

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“…Calculations were performed using the Gaussian09 package, at the B3LYP level of theory using restricted and unrestricted approximations of the Kohn–Sham equations, depending on the total number of electrons . In all cases, we employed the effective core potential basis set LanL2DZ, − which proved to be suitable for geometry and spectroscopic calculations in related ruthenium polypyridines . All the calculations were performed using an UltraFine grid.…”

Section: Methodsmentioning

confidence: 99%

Ru Monoimines with Extended Excited-State Lifetimes and Geometrical Modulation of Photoinduced Mixed-Valence Interactions

et al. 2023

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The photophysical properties of monodentate-imine ruthenium complexes do not usually fulfil the requirements for supramolecular solar energy conversion schemes. Their short excited-state lifetimes, like the 5.2 ps metal-to-ligand charge transfer (MLCT) lifetime of [Ru(py)4Cl(L)]+ with L = pz (pyrazine), preclude bimolecular or long-range photoinduced energy or electron transfer reactions. Here, we explore two strategies to extend the excited-state lifetime, based on the chemical modification of the distal N atom of pyrazine. On one hand, we used L = pzH+, where protonation stabilized MLCT states, rendering thermal population of MC states less favorable. On the other hand, we prepared a symmetric bimetallic arrangement in which L = {(μ-pz)Ru(py)4Cl} to enable hole delocalization via photoinduced mixed-valence interactions. A lifetime extension of 2 orders of magnitude is accomplished, with charge transfer excited states living 580 ps and 1.6 ns, respectively, reaching compatibility with bimolecular or long-range photoinduced reactivity. These results are similar to those obtained with Ru pentaammine analogues, suggesting that the strategy employed is of general applicability. In this context, the photoinduced mixed-valence properties of the charge transfer excited states are analyzed and compared with those of different analogues of the Creutz–Taube ion, demonstrating a geometrical modulation of the photoinduced mixed-valence properties.

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Where’s the Spin? A DFT Study of Mixed-Valence Cyanide-Bridged Ruthenium Polypyridines

Cited by 4 publications

References 0 publications

Influence of the CN Orientation on the Degree of Electron Delocalization of Ru–Ru–Ru Mixed-Valent Complexes

Influence of the CN Orientation on the Degree of Electron Delocalization of Ru–Ru–Ru Mixed-Valent Complexes

A Strongly Coupled Biruthenium Complex as Catalyst for the Water Oxidation Reaction

Ru Monoimines with Extended Excited-State Lifetimes and Geometrical Modulation of Photoinduced Mixed-Valence Interactions

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