Correlating Properties in Iron(III) Complexes: A DFT Description of Structure, Redox Potential and Spin Crossover Phenomena

Flores‐Leonar, Martha M.; Moreno‐Esparza, Rafael; Ugalde‐Saldívar, Víctor M.; Amador‐Bedolla, Carlos

doi:10.1002/slct.201700547

Cited by 10 publications

(6 citation statements)

References 29 publications

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“…Remarkably, the ionization energies and EAs gave absolute errors starting from 0.9 to 5.9% . The BPW91/6-311 + G(2d) results approach the outcomings yielded by more sophisticated and expensive methods, of a multireference character, − as that proposed by Tzeli et al, being affordable to the study of small iron–carbon clusters.…”

Section: Computational Detailssupporting

confidence: 53%

Small Transition-Metal Mixed Clusters as Activators of the C–O Bond. Fe_nCu_m–CO (n + m = 6): A Theoretical Approach

et al. 2021

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Binding of carbon monoxide, CO, and its activation on the surface of the Fe n Cu m CO (n + m = 6) clusters are studied in this work. Using the BPW91/6-311 + G(2d) method, we have found that adsorption of the CO molecule on the surface of Fe n Cu m (n + m = 6) clusters is thermochemically favorable. Atop and bridge CO cluster coordinations appear for pure, Fe 6 and Cu 6 , and mixed, Fe 2 Cu 4 and Fe 4 Cu 2 , clusters. Threefold coordination takes place for Fe 3 Cu 3 −CO where the CO bond length, d CO , suffers a largest increase from 1.128 ± 0.014 Å for bare CO up to 1.21 Å. The CO stretching, ν CO , as an indicator for the CO bond weakening is redshifted, from 2099 ± 4 cm −1 for isolated CO up to 1690 cm −1 for Fe 3 Cu 3 CO and 1678 cm −1 for Fe 6 CO. In addition, in Cu 6 CO, the strongest CO bond is slightly weakened as it has a bond length of 1.15 Å and a ν CO of 2029 cm −1 . There is a correlation between the CO bond weakening and the increase of CO coordination in Fe n Cu m CO, which in turns promotes the transference of charges from the metal core into the antibonding orbitals of CO. Substitution of up to three Cu atoms in Fe 6 increases the adsorption energies and the activation of CO. Indeed, Fe n Cu m (n + m = 6) are promising clusters to catalyze CO dissociation, particularly Fe 3 Cu 3 , Fe 5 Cu, and Fe 6 , which have large CO bond lengths and CO adsorption energies. The Bader analysis of the electronic density indicates that Fe n Cu m CO species with threefold coordination show a rise in the C−O covalent character due to the less electronic polarization. They also show important M → CO charge transfer, which favors the weakening of the CO bond.

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Section: Computational Detailssupporting

confidence: 53%

Small Transition-Metal Mixed Clusters as Activators of the C–O Bond. Fe_nCu_m–CO (n + m = 6): A Theoretical Approach

et al. 2021

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“…Also it has been proven that, for the electron affinity calculated for bare Fe 4 , BPW91/6-311+G(2d) performs better than using other functionals, such as B97D, M11L, or PBE0 . Lastly, the BPW91/6-311+G(2d) method has been shown to approach the results yielded by more sophisticated and expensive methodologies, − as that proposed by Tzeli et al Thus, BPW91/6-311+G(2d) is used in this work, since it has been proven to be affordable to inspect exhaustively the potential energy surface of Fe n CO, n = ≤ 20, needed for its correct characterization (Table ).…”

Section: Methodsmentioning

confidence: 90%

Carbon Monoxide Activation on Small Iron Magnetic Cluster Surfaces, Fe_nCO, n = 1–20. A Theoretical Approach

et al. 2020

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The chemical activation of the carbon monoxide (CO) molecule on the surface of iron clusters Fe n (n = 1–20) is studied in this work. By means of density functional theory (DFT) all-electron calculations, we have found that the adsorption of CO over the bare magnetic Fe n (n = 1–20) clusters is thermochemically favorable. The Fe n –CO interaction increases the C–O bond length, from 1.128 ± 0.014 Å, for isolated CO, up to 1.251 Å, for Fe9CO. Also, the calculated wavenumbers associated with the stretching modes νCO are decreased, or red-shifted, as another indicator of the CO bond weakening, passing from 2099 ± 4 to 1438 cm–1. Markedly, wavenumbers of vibrational modes νCO agree admirably well in comparison with experimental results reported for Fe n CO (n = 1, 18–20), getting small errors below 2.6%. The C–O bond is enlarged on the Fe n CO (n = 1–20) composed systems, as the CO molecule increases its bonding, charge transference, and coordination with the iron cluster. Therefore, small bare iron particles Fe n (n = 1–20) can be proposed to promote the CO dissociation, especially Fe9CO, which has been proven to obtain the most prominent activation of the strong C–O bond by means of the charge transference from the metal core.

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“…At this point, it is worth noting the accuracy of the method. The functional employed has proved to accurately describe C−C bond lengths 46 and non-covalent distances such as those present in the ferrocene system 47 thanks to the inclusion of dispersion corrections. Despite the adequate performance on the geometry, Fokin et al, reported an overestimation of a few kcal mol −1 in the description of rotational barriers.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Concentration Effects on the First Reduction Process of Methyl Viologens and Diquat Redox Flow Battery Electrolytes

Martínez‐González

Flores‐Leonar

Amador‐Bedolla

et al. 2021

ACS Appl. Energy Mater.

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Analyte concentration effects on the first reduction process of methyl viologens and diquat redox flow battery electrolytes were examined by cyclic voltammetry in aqueous media. A simple one-electron transfer mechanism to form radical cations was detected for diquat, 4,4′-dimethyl diquat, and bis(3trimethylammonio)-propyl viologen compounds. The radical cations attach to the electrode surface when the source of their electrogeneration is methyl viologen molecules bearing PF 6 − ions as a counterpart. However, this inner sphere reduction mechanism was not observed in methyl viologen having an I − counterion. For the latter compound, as well as for 5,5′-dimethyl diquat and 1,1′bis(3-sulfonatopropyl)-4,4′-bipyridinium, a piece of experimental evidence for unexpected, fast, and reversible dimerization interactions between their electrogenerated radical cations is presented. To get information on these bimolecular interactions, a screening methodology (using different levels of theory) was employed in finding suitable dimeric structures and their related interaction energies. By using diquat as a reference system, a relationship between calculated interaction energies and the corresponding experimental dimerization constants was obtained. The examination of redox-active molecules using this experimental and theoretical approach will allow a better selection of redox flow battery electrolytes.

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Correlating Properties in Iron(III) Complexes: A DFT Description of Structure, Redox Potential and Spin Crossover Phenomena

Cited by 10 publications

References 29 publications

Small Transition-Metal Mixed Clusters as Activators of the C–O Bond. Fe_nCu_m–CO (n + m = 6): A Theoretical Approach

Small Transition-Metal Mixed Clusters as Activators of the C–O Bond. Fe_nCu_m–CO (n + m = 6): A Theoretical Approach

Carbon Monoxide Activation on Small Iron Magnetic Cluster Surfaces, Fe_nCO, n = 1–20. A Theoretical Approach

Concentration Effects on the First Reduction Process of Methyl Viologens and Diquat Redox Flow Battery Electrolytes

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Correlating Properties in Iron(III) Complexes: A DFT Description of Structure, Redox Potential and Spin Crossover Phenomena

Cited by 10 publications

References 29 publications

Small Transition-Metal Mixed Clusters as Activators of the C–O Bond. FenCum–CO (n + m = 6): A Theoretical Approach

Small Transition-Metal Mixed Clusters as Activators of the C–O Bond. FenCum–CO (n + m = 6): A Theoretical Approach

Carbon Monoxide Activation on Small Iron Magnetic Cluster Surfaces, FenCO, n = 1–20. A Theoretical Approach

Concentration Effects on the First Reduction Process of Methyl Viologens and Diquat Redox Flow Battery Electrolytes

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Small Transition-Metal Mixed Clusters as Activators of the C–O Bond. Fe_nCu_m–CO (n + m = 6): A Theoretical Approach

Small Transition-Metal Mixed Clusters as Activators of the C–O Bond. Fe_nCu_m–CO (n + m = 6): A Theoretical Approach

Carbon Monoxide Activation on Small Iron Magnetic Cluster Surfaces, Fe_nCO, n = 1–20. A Theoretical Approach