Ce and Eu anomalies in zircon as proxies for the oxidation state of magmas

2012 ◽  
Vol 97 ◽  
pp. 70-87 ◽  
Author(s):  
Dustin Trail ◽  
E. Bruce Watson ◽  
Nicholas D. Tailby
Keyword(s):  
Oxidation State ◽  
Ce And Eu Anomalies

Chromium oxidation state mapping in human cells

2003 ◽  
Vol 104 ◽  
pp. 289-292 ◽  
Author(s):  
R. Ortega ◽  
B. Fayard ◽  
M. Salomé ◽  
G. Devès ◽  
J. Susini
Keyword(s):  
Oxidation State ◽  
Human Cells ◽  
Chromium Oxidation

A Short Synthesis of (+)-Brefeldin C via Enantioselective Radical Hydroalkynylation

2019 ◽  
Author(s):  
Lars Gnägi ◽  
Severin Vital Martz ◽  
Daniel Meyer ◽  
Robin Marc Schärer ◽  
Philippe Renaud
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Oxidation State ◽  
Single Step ◽  
Radical Process ◽  
Target Molecule ◽  
Short Synthesis ◽  
The One

<div><div><div><div><p>A very concise total synthesis of (+)-brefeldin C starting from 2-furanylcyclopentene is described. This approach is based on an unprecedented enantioselective radical hydroalkynylation process to introduce the two cyclopentane stereocenters in a single step. The use of a furan substituent allows to achieve a high trans diastereoselectivity during the radical process and it contains the four carbon atoms C1–C4 of the natural product in an oxidation state closely related to the one of the target molecule. The eight-step synthesis require six product purifications and it provides (+)-brefeldin C in 18% overall yield.</p></div></div></div></div>

Piperazine as an Inexpensive and Efficient Ligand for Pd-Catalyzed Homocoupling Reactions to Synthesize Bipyridines and Their Analogues

2019 ◽  
Vol 16 (1) ◽  
pp. 173-180
Author(s):  
Mingwei Chen ◽  
Jinyu Hu ◽  
Xiaoli Tang ◽  
Qiming Zhu
Keyword(s):  
Transition Metal ◽  
Oxidation State ◽  
Coupling Reaction ◽  
Aryl Halides ◽  
Metal Species ◽  
Good Substrate ◽  
Active Metal ◽  
Homocoupling Reaction ◽  
Catalytic Cycles ◽  
Reductive Homocoupling

Aim and Objective: The synthesis of bipyridines, especially 2, 2’-bipyridines, remains challenging because the catalytic cycle can be inhibited due to coordination of bipyridine to transition metal. Thus, the development of efficient methods for the synthesis of bipyridines is highly desirable. In the present work, we presented a promising approach for preparation of bipyridines via a Pd-catalyzed reductive homocoupling reaction with simple piperazine as a ligand. Materials and Methods: Simple and inexpensive piperazine was used as a ligand for Pd-catalyzed homocoupling reaction. The combination of Pd(OAc)2 and piperazine in dimethylformamide (DMF) was observed to form an excellent catalyst and efficiently catalyzed the homocoupling of azaarenyl halides, in which DMF was used as the solvent without excess reductants although stoichiometric reductant was generally required to generate the low-oxidation-state active metal species in the catalytic cycles. </P><P> Results: In this case, good to excellent yields of bipyridines and their (hetero) aromatic analogues were obtained in the presence of 2.5 mol% of Pd(OAc)2 and 5 mol% of piperazine, using K3PO4 as a base in DMF at 140°C. Conclusion: According to the results, piperazine as an inexpensive and efficient ligand was used in the Pd(OAc)2-catalyzed homocoupling reaction of heteroaryl and aryl halides. The coupling reaction was operationally simple and displayed good substrate compatibility.

Voltammetric Studies of Some Novel Fe(III) Complexes with Quadridentate Ligands. The Axial Ligand-Exchange Reactions in DMF and DMSO

1995 ◽  
Vol 60 (7) ◽  
pp. 1140-1157 ◽  
Author(s):  
Ljiljana S. Jovanovic ◽  
Luka J. Bjelica
Keyword(s):  
Oxidation State ◽  
Chemical Reactions ◽  
Ligand Exchange ◽  
Kinetic Data ◽  
Central Atom ◽  
Axial Ligand ◽  
Exchange Reactions ◽  
Ligand Effect ◽  
Condensation Products ◽  
Voltammetric Studies

The electrochemistry of four novel Fe(III) complexes of the type [Fe(L)Cl], involving quadridentate ligands based on the condensation products of benzoylacetone-S-methylisothiosemicarbazone with salicylaldehyde, 5-chlorosalicylaldehyde, 3,5-dichlorosalicylaldehyde or 5-nitrosalicylaldehyde, was studied in DMF and DMSO at a GC electrode. All complexes undergo a two-step one-electron reductions, usually complicated by chemical reactions. In solutions containing Cl-, the ligand-exchange reactions Cl--DMF and Cl--DMSO take place. Stability of the chloride-containing complexes was discussed in terms of the coordinated ligand effect, oxidation state of the central atom and, in particular, of the donor effect of the solvent. Some relevant kinetic data were calculated.

Studies of the Synthesis of Large VAPO-5 Crystals and Incorporation of Vanadium Ions

1992 ◽  
Vol 57 (4) ◽  
pp. 767-773 ◽  
Author(s):  
Jan Kornatowski ◽  
Mikhail Sychev ◽  
Werner H. Baur ◽  
Gerd Finger
Keyword(s):  
Oxidation State ◽  
Molecular Sieve ◽  
Model Substance ◽  
Vanadium Ions

The molecular sieve VAPO-5 has been synthesized hydrothermally in form of large crystals up to 660 μm in length. They have been used as a model substance for the study of vanadium incorporation into the framework. Our results show that vanadium was incorporated into the framework though in relatively small amounts. The results are in agreement with earlier findings for powder preparations of VAPO-5, except for the oxidation state of the vanadium ions and its stability. These conclusions agree with those arrived at previously for vanadium silicate KVS-5.

Gd/Sm dopant-modified oxidation state and defect generation in nano-ceria

2014 ◽  
Vol 260 ◽  
pp. 21-29 ◽  
Author(s):  
S.A. Acharya ◽  
V.M. Gaikwad ◽  
S.W. D'Souza ◽  
S.R. Barman
Keyword(s):  
Oxidation State ◽  
Defect Generation ◽  
Nano Ceria

Europium oxidation state and local structure in silicate glasses

2012 ◽  
Vol 97 (5-6) ◽  
pp. 918-929 ◽  
Author(s):  
M. R. Cicconi ◽  
G. Giuli ◽  
E. Paris ◽  
W. Ertel-Ingrisch ◽  
P. Ulmer ◽  
...  
Keyword(s):  
Oxidation State ◽  
Local Structure ◽  
Silicate Glasses ◽  
State And Local

scholarly journals Ni Oxidation State and Ligand Saturation Impact on the Capability of Octaazamacrocyclic Complexes to Bind and Reduce CO2

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4139
Author(s):  
Barbora Vénosová ◽  
Ingrid Jelemenská ◽  
Jozef Kožíšek ◽  
Peter Rapta ◽  
Michal Zalibera ◽  
...  
Keyword(s):  
Quantum Theory ◽  
Oxidation State ◽  
Central Atom ◽  
Population Analysis ◽  
Mulliken Population Analysis ◽  
Mulliken Population ◽  
Theoretical Methods ◽  
Ni Oxidation ◽  
Shed Light

Two 15-membered octaazamacrocyclic nickel(II) complexes are investigated by theoretical methods to shed light on their affinity forwards binding and reducing CO2. In the first complex 1[NiIIL]0, the octaazamacrocyclic ligand is grossly unsaturated (π-conjugated), while in the second 1[NiIILH]2+ one, the macrocycle is saturated with hydrogens. One and two-electron reductions are described using Mulliken population analysis, quantum theory of atoms in molecules, localized orbitals, and domain averaged fermi holes, including the characterization of the Ni-CCO2 bond and the oxidation state of the central Ni atom. It was found that in the [NiLH] complex, the central atom is reduced to Ni0 and/or NiI and is thus able to bind CO2 via a single σ bond. In addition, the two-electron reduced 3[NiL]2− species also shows an affinity forwards CO2.

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