Group 8 Metal–Metal Bonds

Tereniak, Stephen J.; Lu, Connie C.

doi:10.1002/9783527673353.ch8

Cited by 14 publications

(13 citation statements)

References 264 publications

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“…20 The bond metrics suggest minimal direct overlap between the iron centers in 2 , which is evident from the formal shortness ratios for the Fe1 contacts (FSR = 1.24 and 1.31). 21 Specifically, the Fe2–Fe3 (3.8612(4) Å) and Fe2/Fe3–Fe1 (2.9038(5), 3.0428(5) Å) distances are longer than typically associated with iron–iron bonds. The cyclophanate is distorted based on the bond metrics and angles relative to those of the M 3 X 3 L series (M = Mn, Fe, Co, Zn, Cu; X = Br – , Cl – , and H – ), which highlights the surprising flexibility of L 3– .…”

Section: Resultsmentioning

confidence: 92%

Reactivity of hydride bridges in a high-spin [Fe₃(μ-H)₃]³⁺ cluster: reversible H₂/CO exchange and Fe–H/B–F bond metathesis

et al. 2017

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Section: Resultsmentioning

confidence: 92%

Reactivity of hydride bridges in a high-spin [Fe₃(μ-H)₃]³⁺ cluster: reversible H₂/CO exchange and Fe–H/B–F bond metathesis

et al. 2017

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“…The average Ru–Ru bond distances of paddlewheel complexes are in the range of 2.2–2.5 Å . On the basis of the Ru–Ru distance of the backbone (3.84 Å) of Ru-TBP, the Ru dimer is not in a paddlewheel configuration; instead, the Ru dimer in the unit cell can be stabilized by solvent molecules or counterions.…”

Section: Results and Discussionmentioning

confidence: 99%

Insights into the Electronic Properties and Charge Transfer Mechanism of a Porphyrin Ruthenium-Based Metal–Organic Framework

et al. 2020

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Metal-organic frameworks (MOFs) have attracted significant attention in the field of solar-driven photo-catalysis. Recently, a porphyrin ruthenium-based MOF (Ru-TBP-Zn) has shown highly efficient co-catalyst-free photocatalytic hydrogen evolution reaction (HER) under visible light in neutral water. Certainly, a system with such features is of great interest for the design of MOF-based photocatalysts. In this work, we have conducted Density Functional Theory (DFT) simulations to provide insights into the unique electronic and optical properties of Ru-TBP-Zn. To do so, we propose two structural models that resolve the coordination of the ruthenium atoms in the metal backbone of Ru-TBP-Zn, both in agreement with the experimental observations. UV/Vis spectra calculations allow identifying the importance of the chargetransfer bands. According to our simulations, two possible charge transfer mechanism can co-exist: the direct photo-induced electron transfer from the porphyrin to the ruthenium upon light absorption, and the relaxation of the visible-light active excited states of the porphyrin to the low-lying ligand-to-metal charge transfer states. Analysis of the photo-generated charge carriers predicts a repulsive interaction energy indicating a low electron-hole recombination rate, required for multi-electron transfer processes such as HER. The understanding of the electronic properties and charge transfer mechanism in Ru-TBP-Zn paves the way for designing efficient porphyrin-based MOFs for photocatalysis.

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“…72,73 This technique has been used to probe a number of homogeneous Pd-catalyzed reactions, [74][75][76][77][78][79] including recent analysis of a Pd-catalyzed aerobic oxidation of an aromatic C-H bond. 80 In order to conduct analogous experiments for the allylic acetoxylation reaction, a reactor was designed and constructed to enable operando studies on the high photon-flux beamline at Argonne National Laboratories (see Supporting Information for details; Figures S3-S6).…”

Section: Interrogation Of the Catalyst Speciation By X-ray Absorptionmentioning

confidence: 99%

Operando Spectroscopic and Kinetic Characterization of Aerobic Allylic C–H Acetoxylation Catalyzed by Pd(OAc)₂/4,5-Diazafluoren-9-one

et al. 2019

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Allylic C-H acetoxylations are among the most widely studied palladium(II)-catalyzed C-H oxidation reactions. While the principal reaction steps are well established, key features of the catalytic mechanisms are poorly characterized, including the identity of the turnover-limiting step and the catalyst resting state. Here, we report a mechanistic study of aerobic allylic acetoxylation of allylbenzene with a catalyst system composed of Pd(OAc) 2 and 4,5-diazafluoren-9-one (DAF). The DAF ligand is unique in its ability to support aerobic catalytic turnover, even in the absence of benzoquinone or other co-catalysts. Herein, we describe operando spectroscopic analysis of the catalytic reaction using X-ray absorption and NMR spectroscopic methods that allow direct observation of the formation and decay of a palladium(I) species during the reaction. Kinetic studies reveal the presence of two distinct kinetic phases: (1) a burst phase, involving rapid formation of the allylic acetoxylation product and formation of the dimeric Pd I complex [Pd I (DAF)(OAc)] 2 , followed by (2) a post-burst phase that coincides with evolution of the catalyst resting state from the Pd I dimer into a π-allyl-Pd II species. The data provide unprecedented insights into the role of ancillary ligands in supporting catalytic turnover with O 2 as the stoichiometric oxidant and establish an important foundation for the development of improved catalysts for allylic oxidation reactions.

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Group 8 Metal–Metal Bonds

Cited by 14 publications

References 264 publications

Reactivity of hydride bridges in a high-spin [Fe₃(μ-H)₃]³⁺ cluster: reversible H₂/CO exchange and Fe–H/B–F bond metathesis

Reactivity of hydride bridges in a high-spin [Fe₃(μ-H)₃]³⁺ cluster: reversible H₂/CO exchange and Fe–H/B–F bond metathesis

Insights into the Electronic Properties and Charge Transfer Mechanism of a Porphyrin Ruthenium-Based Metal–Organic Framework

Operando Spectroscopic and Kinetic Characterization of Aerobic Allylic C–H Acetoxylation Catalyzed by Pd(OAc)₂/4,5-Diazafluoren-9-one

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Group 8 Metal–Metal Bonds

Cited by 14 publications

References 264 publications

Reactivity of hydride bridges in a high-spin [Fe3(μ-H)3]3+ cluster: reversible H2/CO exchange and Fe–H/B–F bond metathesis

Reactivity of hydride bridges in a high-spin [Fe3(μ-H)3]3+ cluster: reversible H2/CO exchange and Fe–H/B–F bond metathesis

Insights into the Electronic Properties and Charge Transfer Mechanism of a Porphyrin Ruthenium-Based Metal–Organic Framework

Operando Spectroscopic and Kinetic Characterization of Aerobic Allylic C–H Acetoxylation Catalyzed by Pd(OAc)2/4,5-Diazafluoren-9-one

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Reactivity of hydride bridges in a high-spin [Fe₃(μ-H)₃]³⁺ cluster: reversible H₂/CO exchange and Fe–H/B–F bond metathesis

Reactivity of hydride bridges in a high-spin [Fe₃(μ-H)₃]³⁺ cluster: reversible H₂/CO exchange and Fe–H/B–F bond metathesis

Operando Spectroscopic and Kinetic Characterization of Aerobic Allylic C–H Acetoxylation Catalyzed by Pd(OAc)₂/4,5-Diazafluoren-9-one