Electronic structure analysis of electron-transfer matrix elements for transition-metal redox pairs

1988 ◽  
Vol 92 (11) ◽  
pp. 3049-3056 ◽  
Author(s):  
Marshall D. Newton
Keyword(s):  
Electron Transfer ◽  
Electronic Structure ◽  
Transition Metal ◽  
Transfer Matrix ◽  
Structure Analysis ◽  
Matrix Elements ◽  
Metal Redox

scholarly journals Unified Mechanistic Understanding of CO2 Reduction to CO on Transition Metal and Single Atom Catalysts

2021 ◽  
Author(s):  
Sudarshan Vijay ◽  
Wen Ju ◽  
Sven Brückner ◽  
Peter Strasser ◽  
Karen Chan
Keyword(s):  
Electron Transfer ◽  
Electronic Structure ◽  
Transition Metal ◽  
Density Functional ◽  
Co2 Reduction ◽  
Electron Transfer Reaction ◽  
Dipole Field ◽  
Single Atom ◽  
Activity Measurements ◽  
Carbon Catalysts

<p>CO is the simplest product from CO<sub>2</sub> electroreduction (CO<sub>2</sub>R), but the identity and nature of its rate limiting step remains controversial. Here we investigate the activity of both transition metals (TMs) and metal-nitrogen doped carbon catalysts (MNCs), and a present unified mechanistic picture of CO<sub>2</sub>R to for both these classes of catalysts. By consideration of the electronic structure through a Newns-Andersen model, we find that on MNCs, like TMs, electron transfer to CO<sub>2</sub><sub> </sub>is facile, such that CO<sub>2</sub> (g) adsorption is driven by adsorbate dipole-field interactions. Using density functional theory with explicit consideration of the interfacial field, we find CO<sub>2</sub> * adsorption to generally be limiting on TMs, while MNCs can be limited by either CO<sub>2</sub>* adsorption or by the proton-electron transfer reaction to form COOH*. We evaluate these computed mechanisms against pH-dependent experimental activity measurements on CO<sub>2</sub>R to CO activity for Au, FeNC, and NiNC. We present a unified activity volcano that, in contrast to previous analyses, includes the decisive CO<sub>2</sub>*<sub> </sub>and COOH* binding strengths as well as the critical adsorbate dipole-field interactions. We furthermore show that MNC catalysts are tunable towards higher activity away from transition metal scaling, due to the stabilization of larger dipoles resulting from their discrete and narrow <i>d</i>-states. The analysis suggests two design principles for ideal catalysts: moderate CO<sub>2</sub>* and COOH* binding strengths as well as large dipoles on the CO<sub>2</sub>*<sub> </sub>intermediate. We suggest that these principles can be exploited in materials with similar electronic structure to MNCs, such as supported single-atom catalysts, molecules, and nanoclusters, 2D materials, and ionic compounds towards higher CO<sub>2</sub>R activity. This work captures the decisive impact of adsorbate dipole-field interactions in CO<sub>2</sub>R to CO and paves the way for computational-guided design of new catalysts for this reaction.</p>

Geometric and Electronic Structure Analysis of the Three-Membered Electron-Transfer Series [(μ-CNR)2[CpCo]2]n (n = 0, 1–, 2−) and Its Relevance to the Classical Bridging-Carbonyl System

2017 ◽  
Vol 36 (11) ◽  
pp. 2126-2140 ◽  
Author(s):  
Charles C. Mokhtarzadeh ◽  
Alex E. Carpenter ◽  
Daniel P. Spence ◽  
Mohand Melaimi ◽  
Douglas W. Agnew ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Electronic Structure ◽  
Structure Analysis

Ubergangsmetallkomplexe mit Schwefelliganden, XXXIII*/ Transition Metal Complexes with Sulfur Ligands, XXXIII*

1987 ◽  
Vol 42 (10) ◽  
pp. 1298-1306 ◽  
Author(s):  
Dieter Sellmann ◽  
Gerhard Binker ◽  
Falk Knoch
Keyword(s):  
Electron Transfer ◽  
Transition Metal ◽  
Metal Complexes ◽  
Structure Analysis ◽  
Transition Metal Complexes ◽  
Model Reaction ◽  
X Ray ◽  
Hydride Complex ◽  
Elemental Analyses

Abstract In order to investigate the specific properties which are associated with metal sulfur cen­ters, the system Ru/S2C6H42- has been studied with respect to the synthesis of new com­plexes and their reactions as well as their structure. cis-(NBu4)(Ru(NO))(PMe4)(S2C6H4)2] reacts with an excess of PMe3 in boiling THF to give the paramagnetic (μeff = 0,96 B. M., 295 K) trans-(NBu4)(Ru(PMe4)2(S2C6H4)2) (I). A plausible intermediate in this reaction is the nitrido complex (NBu4)(Ru(N)(S2C6H4)2) (2) since 2 gives with one equivalent of PMe3 a very labile product which is probably (NBu4)(Ru(N)(PMe4)(S2C6H4)2) (3). but reacts with an excess of PMe3 even at 20 °C to give 1. The Ru(III) complex 1 is easily oxidized by O2 or PhN2BF4 to yield the diamagnetic Ru(IV) species trans-(Ru(PMe3)2(S2C6H4)2) (4). Remarkably, the transformation of 1 into 4 is achieved also by H+ ions, providing a model reaction for the coupled H+-electron transfer which has been discussed for substrate reactions at metal sulfur centers of enzymes. - The reaction of RuCl2(PMe3)4 with S2C6H42- yields [Ru(PMe3)4(S2C6H4)] (5) at 20 °C, even if an excess of S2C6H42- is applied. Upon heating in THF or EtOH, 5 looses one PMe3 ligand to give the 16e -complex [Ru(PMe4)4(S2C6H4)] (6) which rapidly coordinates CO to give [Ru(CO)(PMe4)4(S2C6H4)] (7); '1P NMR indicates a meridional coordination of PMe4 in 7, and consequently CO must be trans to S2C6H42-. 6 reacts also with LiAlH4 to yield a very sensitive hydride complex to which the tentative formula [Ru(H)2(PMe3)2(S2C6H4)] is assigned. All compounds were characterized by elemental analyses and spectroscopic means, the structures of I and 5 were determined by X-ray structure analysis.

Electronic structure in the transition metal block and its implications for light harvesting

Science ◽  
2019 ◽  
Vol 363 (6426) ◽  
pp. 484-488 ◽  
Author(s):  
James K. McCusker
Keyword(s):  
Electron Transfer ◽  
Electronic Structure ◽  
Excited State ◽  
Transition Metal ◽  
Solar Energy ◽  
Photoinduced Electron Transfer ◽  
Chemical Processes ◽  
Transition Series ◽  
Earth Abundant ◽  
Metal Block

Transition metal–based chromophores play a central role in a variety of light-enabled chemical processes ranging from artificial solar energy conversion to photoredox catalysis. The most commonly used compounds include elements from the second and third transition series (e.g., ruthenium and iridium), but their Earth-abundant first-row analogs fail to engage in photoinduced electron transfer chemistry despite having virtually identical absorptive properties. This disparate behavior stems from fundamental differences in the nature of 3d versus 4d and 5d orbitals, resulting in an inversion in the compounds’ excited-state electronic structure and undermining the ability of compounds with first-row elements to engage in photoinduced electron transfer. This Review will survey the key experimental observations establishing this difference in behavior, discuss the underlying reasons for this phenomenon, and briefly summarize efforts that are currently under way to alter this paradigm and open the door to new opportunities for using Earth-abundant materials for photoinduced electron transfer chemistries.

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