Copper(II), copper(III) and nickel(II) complexes of the macrocyclic diamide ligands 1,4,7,10-tetra-azacyclododecane-2,3-dione, 1,4,7,11-tetra-azacyclotridecane-2,3-dione, 1,4,8,11-tetra-azacyclotetradecane-2,3-dione and electrochemical studies on the copper and nickel complexes of 1,4,8,11-tetra-azacyclotetradecane-5,7-dione

1982 ◽  
Vol 59 ◽  
pp. 147-153 ◽  
Author(s):  
Robert W Hay ◽  
Ramesh Bembi ◽  
Walter Sommerville
Keyword(s):  
Nickel Complexes ◽  
Electrochemical Studies ◽  
Macrocyclic Diamide ◽  
Diamide Ligands

Electrochemical studies of nickel complexes containing phoshprus(III) ligands and their related Ziegler catalysts

1989 ◽  
Vol 367 (1-2) ◽  
pp. 205-232 ◽  
Author(s):  
A.A. Pozdeeva ◽  
U.M. Dzhemilev ◽  
N.R. Popod'ko ◽  
R.I. Khusnutdinov ◽  
S.I. Zhdanov ◽  
...  
Keyword(s):  
Nickel Complexes ◽  
Electrochemical Studies

Synthesis and Electrochemical Studies of Nickel β-Diketonate Complexes Incorporating Asymmetric Diimine Ligands

2010 ◽  
Vol 63 (1) ◽  
pp. 75 ◽  
Author(s):  
Phimphaka Harding ◽  
David J. Harding ◽  
Nitisastr Soponrat ◽  
Kittiya Tinpun ◽  
Sirirat Samuadnuan ◽  
...  
Keyword(s):  
Electrochemical Behaviour ◽  
Nickel Complexes ◽  
Electrochemical Studies ◽  
Peak Potential ◽  
Aryl Ring ◽  
X Ray ◽  
Coordination Modes ◽  
X Ray Crystallography ◽  
Diimine Ligands

The reaction of ppaX {(4-X-phenyl)-pyridin-2-ylmethylene-amine; X = H, Me, Et, OMe, F, Cl, Br, and I} with [Ni(β-diketonate)2(H2O)2] {β-diketonate = 1,3-diphenylpropanedionate (dbm), 2,2,6,6-tetramethyl-3,5-heptadionate (tmhd), or hexafluoroacetylacetonate (hfac)} yields a series of nickel complexes. X-ray crystallography reveals octahedral coordinated nickel centres with a cis arrangement of the β-diketonate ligands. The β-diketonate ligands adopt ‘planar’ or ‘bent’ coordination modes, whereas the aryl ring of the ppaX ligand is twisted with respect to the pyridylimine unit. The electrochemical behaviour of the complexes reveals quasi-reversible or irreversible one-electron oxidation to Ni(iii) in the case of the [Ni(tmhd)2(ppaX)] and [Ni(dbm)2(ppaX)] complexes, respectively. The peak potential for oxidation is dependent on the type of β-diketonate ligand but essentially independent of the substituent, X, on the ppaX ligand. The [Ni(β-diketonate)2(ppaX)] complexes (X = F, Cl, Br, and I) also undergo ligand based reduction.

scholarly journals Synthesis, Spectroscopic and Electrochemical Studies of Mononuclear Fe(II) and Ni(II) Complexes Containing a Macrocyclic Ligand Derived from Pyridine-2,6-dicarboxaldehyde and 1,2-Bis(2-aminoethoxy) Ethane

2011 ◽  
Vol 3 (3) ◽  
pp. 599-607 ◽  
Author(s):  
M. M. Alam ◽  
R. Begum ◽  
S. M. M. Rahman ◽  
S. M. S. Islam
Keyword(s):  
Schiff Base ◽  
Macrocyclic Ligand ◽  
Nickel Complexes ◽  
Spectroscopic Studies ◽  
Octahedral Geometry ◽  
Electrochemical Studies ◽  
Metal Source ◽  
Elemental Analyses ◽  
Uv Visible ◽  
Metal Perchlorate

The cyclic (2+2) template condensation of 2,6-pyridinedicarboxaldehyde with 1,2-bis(2-aminoethoxy) ethane using Pb(SCN)2 as the metal source gave dinuclear lead(II) complex, Pb2L1(SCN)4 (1), where L1 is tetra-Schiff-base macrocycle. The transmetallation treatment of 1 with suitable metal perchlorate yield [FeL1](ClO4)2 (2) and [NiL1](ClO4)2 (3). The complexes (2 & 3) have been characterized by elemental analyses, IR, UV-visible, and ESI-MS spectroscopy. Based on spectral data, octahedral geometry may be proposed for these complexes. The electrochemical behavior of iron and nickel complexes is reported.Keywords:  Macrocyclic complexes; Spectroscopic studies; 1,2-Bis(2-aminoethoxy) ethane; Charge transfer.© 2011 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: 10.3329/jsr.v3i3.7231               J. Sci. Res. 3 (3), 609-617 (2011)

A Pyridinic Fe-N4 Macrocycle Effectively Models the Active Sites in Fe/N-Doped Carbon Electrocatalysts

2020 ◽  
Author(s):  
Travis Marshall-Roth ◽  
Nicole J. Libretto ◽  
Alexandra T. Wrobel ◽  
Kevin Anderton ◽  
Nathan D. Ricke ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Active Sites ◽  
Catalytic Properties ◽  
Reduction Reaction ◽  
Iron Phthalocyanine ◽  
Electrochemical Studies ◽  
Onset Potential ◽  
Nitrogen Doped Carbon ◽  
Iron Active Sites

Iron- and nitrogen-doped carbon (Fe-N-C) materials are leading candidates to replace platinum in fuel cells, but their active site structures are poorly understood. A leading postulate is that iron active sites in this class of materials exist in an Fe-N<sub>4</sub> pyridinic ligation environment. Yet, molecular Fe-based catalysts for the oxygen reduction reaction (ORR) generally feature pyrrolic coordination and pyridinic Fe-N<sub>4</sub> catalysts are, to the best of our knowledge, non-existent. We report the synthesis and characterization of a molecular pyridinic hexaazacyclophane macrocycle, (phen<sub>2</sub>N<sub>2</sub>)Fe, and compare its spectroscopic, electrochemical, and catalytic properties for oxygen reduction to a prototypical Fe-N-C material, as well as iron phthalocyanine, (Pc)Fe, and iron octaethylporphyrin, (OEP)Fe, prototypical pyrrolic iron macrocycles. N 1s XPS signatures for coordinated N atoms in (phen<sub>2</sub>N<sub>2</sub>)Fe are positively shifted relative to (Pc)Fe and (OEP)Fe, and overlay with those of Fe-N-C. Likewise, spectroscopic XAS signatures of (phen<sub>2</sub>N<sub>2</sub>)Fe are distinct from those of both (Pc)Fe and (OEP)Fe, and are remarkably similar to those of Fe-N-C with compressed Fe–N bond lengths of 1.97 Å in (phen<sub>2</sub>N<sub>2</sub>)Fe that are close to the average 1.94 Å length in Fe-N-C. Electrochemical studies establish that both (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe have relatively high Fe(III/II) potentials at ~0.6 V, ~300 mV positive of (OEP)Fe. The ORR onset potential is found to directly correlate with the Fe(III/II) potential leading to a ~300 mV positive shift in the onset of ORR for (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe relative to (OEP)Fe. Consequently, the ORR onset for (phen<sub>2</sub>N<sub>2</sub>)Fe and (Pc)Fe is within 150 mV of Fe-N-C. Unlike (OEP)Fe and (Pc)Fe, (phen<sub>2</sub>N<sub>2</sub>)Fe displays excellent selectivity for 4-electron ORR with <4% maximum H<sub>2</sub>O<sub>2</sub> production, comparable to Fe-N-C materials. The aggregate spectroscopic and electrochemical data establish (phen<sub>2</sub>N<sub>2</sub>)Fe as a pyridinic iron macrocycle that effectively models Fe-N-C active sites, thereby providing a rich molecular platform for understanding this important class of catalytic materials.<p><b></b></p>

Spatiotemporal Control of Amide Radicals During Photocatalysis

2020 ◽  
Author(s):  
Shogo Mori ◽  
Takahiro Aoki ◽  
Kaliyamoorthy Selvam ◽  
Shunichi Fukuzumi ◽  
Jieun Jung ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Nickel Complex ◽  
Nickel Complexes ◽  
Semiconductor Material ◽  
Radical Reactions ◽  
Substitution Reactions ◽  
Carbon Neutrality ◽  
Spatiotemporal Control ◽  
Scalable Production ◽  
Salt Waste

Despite the continuing popularity of radical reactions in organic synthesis, much remains to be explored in this area. Herein, we describe how spatiotemporal control can be exerted over the formation and reactivity of divergent exchangeable formamide radicals using nickel complexes with a semiconductor material (TiO<sub>2</sub>) under irradiation from near-UV–Vis light. Depending on the bipyridine ligand used and the quantity of the nickel complex that is hybridized on or nonhydridized over the TiO<sub>2</sub> surface, these radicals selectively undergo substitution reactions at the carbon center of carbon–bromine bonds that proceed via three different pathways. As the scalable production of formamides from CO<sub>2</sub> does not produce salt waste, these methods could add a new dimension to the search for carbon neutrality through the indirect incorporation of CO<sub>2</sub> into organic frameworks.

Inhibition Effects of Some Organic Compounds on Zinc Corrosion in 3.5% NaCl

2008 ◽  
Vol 59 (5) ◽  
Author(s):  
Viorel Branzoi ◽  
Alina Pruna ◽  
Florina Branzoi
Keyword(s):  
Organic Compounds ◽  
Electrochemical Impedance ◽  
Corrosion Process ◽  
Diffusion Control ◽  
Cathodic Reaction ◽  
Zinc Electrode ◽  
Electrochemical Studies ◽  
Nacl Solution ◽  
Sodium Dodecylsulphate ◽  
Zinc Corrosion

The inhibition of zinc corrosion in 3.5% NaCl solution by some organic compounds (sodium dodecylsulphate (SDS), sodium dodecylbenzosulphonate (SDBS) and sodium 1,4-bis(2-etylhexyl) sulphosuccinate (AOT)) was investigated. The inhibition efficiencies were determined by polarization measurements of the zinc electrode in the solution. Electrochemical impedance spectroscopy (EIS) was also used for electrochemical studies of zinc electrode in this medium. The results showed that the used surfactants inhibit the cathodic reaction of hydrogen evolution and at low anodic overvoltage the corrosion process is under activation control, while at high anodic overvoltage the process is under diffusion control.

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