Electronic Structure of a Formal Iron(0) Porphyrin Complex Relevant to CO<sub>2</sub> Reduction

Römelt, Christina; Song, Jinshuai; Tarrago, Maxime; Rees, Julian A.; Gastel, Maurice van; Weyhermüller, Thomas; DeBeer, Serena; Bill, Eckhard; Neese, Frank; Ye, Shengfa

doi:10.1021/acs.inorgchem.7b00401

Cited by 107 publications

(118 citation statements)

References 62 publications

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“…Such restricted-channel TD-DFT calculations have been applied extensively for K-edge XAS spectra of transition metal complexes. 19,41,[53][54][55][56][57][58][59] The calculated XAS intensities include second-order contributions due to the magnetic-dipole and electric-quadrupole transition moments, which are calculated using the origin-independent formalism of Ref. 37.…”

Section: Computational Methodologymentioning

confidence: 99%

Revisiting the Dependence of Cu K-Edge X-ray Absorption Spectra on Oxidation State and Coordination Environment

Rudolph

Jacob

2018

Inorg. Chem.

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X-ray absorption spectroscopy (XAS) at the Cu K-edge is an important tool for probing the properties of copper centers in transition-metal chemistry and catalysis. However, the interpretation of experimental XAS spectra requires a detailed understanding of the dependence of spectroscopic features on the local geometric and electronic structure, which can be established by theoretical X-ray spectroscopy. Here, we present a systematic computational study of the Cu K-edge XAS spectra of selected Cu complexes based on time-dependent density-functional theory in combination with a molecular orbital analysis of the relevant transitions. For a series of Cu ammine model complexes as well as a comprehensive test set of 12 Cu(I) and 5 Cu(II) complexes, we revisit the dependence of the pre-edge region in Cu K-edge XAS spectra on oxidation state and coordination geometry. While our calculations confirm earlier experimental assignments, we can also reveal additional signatures of the ligand orbitals and identify the underlying orbital interactions. The comprehensive picture revealed by this study will provide a reliable basis for the interpretation of in situ Cu K-edge XAS spectra of catalytic intermediates.

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Section: Computational Methodologymentioning

confidence: 99%

Revisiting the Dependence of Cu K-Edge X-ray Absorption Spectra on Oxidation State and Coordination Environment

Rudolph

Jacob

2018

Inorg. Chem.

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“…For the isomer shift calculations, the following values were used: a = À0.376, b = 4.130, and C = 11810. [40] Molecular orbital pictures and spin-density plots were generated starting from the optimized structures, and singlepoint energy calculations were carried out by using the Gaussian 16 program. [41] The B3LYP-D3BJ functional and SDD [42] basis sets as well as associated effective core potentials were used for Fe and Mo, and the def2TZVP [38,39] basis sets were used for other atoms.…”

Section: Methodsmentioning

confidence: 99%

Cubane‐Type [Mo₃S₄M] Clusters with First‐Row Groups 4–10 Transition‐Metal Halides Supported by C₅Me₅ Ligands on Molybdenum

Ohki

Uchida

Hara

et al. 2018

Chemistry A European J

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A synthetic protocol was developed for a series of cubane-type [Mo S M] clusters that incorporate halides of first-row transition metals (M) from Groups 4-10. This protocol is based on the anionic cluster platform [Cp* Mo S ] ([1] ; Cp*=η -C Me ), which crystallizes when K(18-crown-6) is used as the counter cation. Treatment of in situ-generated [1] with such transition-metal halides led to the formation of [Mo S M] clusters, in which the M/halide ratio gradually changes from 1:2 to 1:1.5 and to 1:1, when moving from early to late transition metals. This trend suggests a tendency for early transition metals to tolerate higher oxidation states and adopt larger ionic radii relative to late transition metals. The properties of the [Mo S Fe] cluster 6 a were investigated in detail by using Fe Mössbauer spectroscopy and computational methods.

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“…From the very first times the catalytic or stoichiometric reactivity of doubly reduced Fe II porphyrin were investigated, until very recently, various spectroscopic techniques have indicated that the Fe II resonance form appears as largely predominant over the Fe 0 form (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). Taking as an example the reduction of CO 2 to CO, the starting molecular reductant would be the Fe II resonance form of the doubly reduced Fe II porphyrin and the final product Fe II CO. From this perspective, the metal oxidation number seems to be invariant over the course of the reaction, and hence the ligand is not only noninnocent but also "redox active."…”

Section: Significancementioning

confidence: 99%

Ligand “noninnocence” in coordination complexes vs. kinetic, mechanistic, and selectivity issues in electrochemical catalysis

Costentin

Savéant

Tard

2018

Proc. Natl. Acad. Sci. U.S.A.

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The world of coordination complexes is currently stimulated by the quest for efficient catalysts for the electrochemical reactions underlying modern energy and environmental challenges. Even in the case of a multielectron-multistep process, catalysis starts with uptake or removal of one electron from the resting state of the catalyst. If this first step is an outer-sphere electron transfer (triggering a "redox catalysis" process), the electron distribution over the metal and the ligand is of minor importance. This is no longer the case with "chemical catalysis," in which the active catalyst reacts with the substrate in an inner-sphere manner, often involving the transient formation of a catalyst-substrate adduct. The fact that, in most cases, the ligand is "noninnocent," in the sense that the electron density and charge gained (or removed) from the resting state of the catalyst are shared between the metal and the ligand, has become common-place knowledge over the last half-century. Insistent focus on a large degree of noninnocence of the ligand in the resting state of the catalyst, even robustly validated by spectroscopic techniques, may lead to undermining the essential role of the metal when such essential issues as kinetics, mechanisms, and product selectivity are dealt with. These points are general in scope, but their discussion is eased by adequately documented examples. This is the case for reactions involving metalloporphyrins as well as vitamin B12 derivatives and similar cobalt complexes for which a wealth of experimental data is available.

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Electronic Structure of a Formal Iron(0) Porphyrin Complex Relevant to CO₂ Reduction

Cited by 107 publications

References 62 publications

Revisiting the Dependence of Cu K-Edge X-ray Absorption Spectra on Oxidation State and Coordination Environment

Revisiting the Dependence of Cu K-Edge X-ray Absorption Spectra on Oxidation State and Coordination Environment

Cubane‐Type [Mo₃S₄M] Clusters with First‐Row Groups 4–10 Transition‐Metal Halides Supported by C₅Me₅ Ligands on Molybdenum

Ligand “noninnocence” in coordination complexes vs. kinetic, mechanistic, and selectivity issues in electrochemical catalysis

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Electronic Structure of a Formal Iron(0) Porphyrin Complex Relevant to CO2 Reduction

Cited by 107 publications

References 62 publications

Revisiting the Dependence of Cu K-Edge X-ray Absorption Spectra on Oxidation State and Coordination Environment

Revisiting the Dependence of Cu K-Edge X-ray Absorption Spectra on Oxidation State and Coordination Environment

Cubane‐Type [Mo3S4M] Clusters with First‐Row Groups 4–10 Transition‐Metal Halides Supported by C5Me5 Ligands on Molybdenum

Ligand “noninnocence” in coordination complexes vs. kinetic, mechanistic, and selectivity issues in electrochemical catalysis

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Electronic Structure of a Formal Iron(0) Porphyrin Complex Relevant to CO₂ Reduction

Cubane‐Type [Mo₃S₄M] Clusters with First‐Row Groups 4–10 Transition‐Metal Halides Supported by C₅Me₅ Ligands on Molybdenum