scholarly journals The biology and chemistry of high-valent iron–oxo and iron–nitrido complexes

2012 ◽  
Vol 3 (1) ◽  
Author(s):  
Johannes Hohenberger ◽  
Kallol Ray ◽  
Karsten Meyer
Keyword(s):  
Nitrido Complexes ◽  
High Valent

High-Valent Iron-Oxo and -Nitrido Complexes: Bonding and Reactivity

2016 ◽  
Vol 56 (9-10) ◽  
pp. 763-772 ◽  
Author(s):  
Bhaskar Mondal ◽  
Lisa Roy ◽  
Frank Neese ◽  
Shengfa Ye
Keyword(s):  
Nitrido Complexes ◽  
High Valent

Mid- to high-valent imido and nitrido complexes of iron

2006 ◽  
Vol 100 (4) ◽  
pp. 634-643 ◽  
Author(s):  
Mark P. Mehn ◽  
Jonas C. Peters
Keyword(s):  
Nitrido Complexes ◽  
High Valent

scholarly journals Cationic Effects on the Effective Hydrogen Atom Bond Dissociation Free Energy of High Valent Manganese Imido Complexes

2021 ◽  
Author(s):  
Nadia Leonard ◽  
Teera Chantarojsiri ◽  
Joseph Ziller ◽  
Jenny Yang
Keyword(s):  
Free Energy ◽  
Hydrogen Atom ◽  
Electric Fields ◽  
Hydrogen Atom Transfer ◽  
Bond Dissociation ◽  
Transfer Path ◽  
Reduction Potentials ◽  
Nitrido Complexes ◽  
Imido Complexes ◽  
High Valent

Local electric fields can alter energy landscapes to impart enhanced reactivity in enzymes and at surfaces. There has been renewed interest on their use in molecular systems, where they can be installed using charged functionalities. Manga-nese(V) salen nitrido complexes (salen = N,N’-ethylenebis(salicylideneaminato)) appended with a crown ether unit con-taining a Na+ (1-Na), K+, (1-K), Ba2+ (1-Ba), Sr2+ (1-Sr), La3+ (1-La), or Eu3+ (1-Eu) cation were investigated to experimen-tally demonstrate the effect of cation-induced electric fields on pKa, E1/2, and the effective bond dissociation free energy (BDFE) of N–H bonds. The series, which includes the manganese (V) salen nitrido without a crown appended, spans 4 units of charge. Bounds for the pKa values of the transient imido complexes were determined by UV-visible and 1H NMR spectroscopy. These values, together with the reduction potentials for the Mn(VI/V) couple measured by cyclic voltamme-try in acetonitrile, were used to calculated the N–H BDFEs of the imidos. Despite spanning >700 mV and >9 pKa units across the series, the hydrogen atom BDFE only spans ~ 5 kcal/mol (between 76 and 81 kcal/mol). These results suggest that incorporation of cationic functionalities is an effective strategy for accessing wide ranges of reduction potentials and pKa while minimally affecting BDFE, which is essential to modulating electron, proton, or hydrogen atom transfer path-ways.

ChemInform Abstract: High-Valent Iron-Oxo and -Nitrido Complexes: Bonding and Reactivity

ChemInform ◽  
2016 ◽  
Vol 47 (47) ◽  
Author(s):  
Bhaskar Mondal ◽  
Lisa Roy ◽  
Frank Neese ◽  
Shengfa Ye
Keyword(s):  
Nitrido Complexes ◽  
High Valent

Mid- to High-Valent Imido and Nitrido Complexes of Iron

ChemInform ◽  
2006 ◽  
Vol 37 (34) ◽  
Author(s):  
Mark P. Mehn ◽  
Jonas C. Peters
Keyword(s):  
Nitrido Complexes ◽  
High Valent

Kinetic Control of Interpenetration in Fe-Biphenyl-4,4′-dicarboxylate MOFs by Coordination and Oxidation Modulation

2018 ◽  
Author(s):  
Dominic Bara ◽  
Claire Wilson ◽  
Max Mörtel ◽  
Marat M. Khusniyarov ◽  
ben slater ◽  
...  
Keyword(s):  
Self Assembly ◽  
Surface Areas ◽  
Metal Precursors ◽  
Additional Coordination ◽  
Fine Control ◽  
Multiple Alternative ◽  
Metal Organic ◽  
Dft Simulations ◽  
High Valent ◽  
And Control

Phase control in the self-assembly of metal-organic frameworks (MOFs) – materials wherein organic ligands connect metal ions or clusters into network solids with potential porosity – is often a case of trial and error. Judicious control over a number of synthetic variables is required to select for the desired topology and control features such as interpenetration and defectivity, which have significant impact on physical properties and application. Herein, we present a comprehensive investigation of self-assembly in the Fe-biphenyl-4,4'-dicarboxylate system, demonstrating that coordination modulation, the addition of competing ligands into solvothermal syntheses, can reliably tune between the kinetic product, non-interpenetrated MIL-88D(Fe), and the thermodynamic product, two-fold interpenetrated MIL-126(Fe). DFT simulations reveal that correlated disorder of the terminal anions on the metal clusters in the interpentrated phase results in H-bonding between adjacent nets and is the thermodynamic driving force for its formation. Coordination modulation slows self-assembly and therefore selects the thermodynamic product MIL-126(Fe), while offering fine control over defectivity, inducing mesoporosity, but electron microscopy shows the MIL-88D(Fe) phase persists in many samples despite not being evident in diffraction experiments, suggesting its presence accounts for the lower than predicted surface areas reported for samples to date. Interpenetration control is also demonstrated by utilizing the 2,2'-bipyridine-5,5'-dicarboxylate linker; DFT simulations show that it is energetically prohibitive for it to adopt the twisted conformation required to form the interpenetrated phase, and are confirmed by experimental data, although multiple alternative phases are identified due to additional coordination of the Fe cations to the N-donors of the ligand. Finally, we introduce oxidation modulation – the concept of using metal precursors in a different oxidation state to that found in the final MOF – as a further protocol to kinetically control self-assembly. Combining coordination and oxidation modulation allows the synthesis of pristine MIL-126(Fe) with BET surface areas close to the predicted maximum capacity for the first time, suggesting that combining the two may be a powerful methodology for the controlled self-assembly of high-valent MOFs.<br><br>

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