Promotion of antiferromagnetic exchange interaction in multinuclear copper(ii) complexes via fused oxamato/oxamidato ligands

2018 ◽  
Vol 47 (45) ◽  
pp. 16164-16181 ◽  
Author(s):  
Saddam Weheabby ◽  
Mohammad A. Abdulmalic ◽  
Matteo Atzori ◽  
Roberta Sessoli ◽  
Azar Aliabadi ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Exchange Interaction ◽  
Transition Metal Ions ◽  
Antiferromagnetic Exchange ◽  
Magnetic Exchange ◽  
Antiferromagnetic Exchange Interaction

Oligo-oxamate type preligands ensure a coplanar orientation of the coordination units of embedded transition metal ions and promote thereby intramolecular magnetic exchange couplings.

Effect of Substitution of Magnetic Metal Ions on Magnetic and Magnetoresistance Properties in LaSr2Mn2O7

2005 ◽  
Vol 475-479 ◽  
pp. 2227-2230
Author(s):  
J. Feng ◽  
Q.B. Bo ◽  
P. Che ◽  
J.P. Wang ◽  
M.F. Lu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Manganese Oxides ◽  
Double Exchange ◽  
Transition Metal Ions ◽  
Tetragonal Symmetry ◽  
Ferromagnetic Property ◽  
Magnetic Exchange ◽  
Magnetic Metal ◽  
Mno6 Octahedron

The layered manganese oxides LaSr2Mn2-xTxO7 (T=Fe, Cr and Ni) has been prepared. The effect of substitution of transition metal ions for Mn on magnetic and magtoresistance properties has been studied. The compound has a tetragonal symmetry and the lattice parameters a decreases with increasing the doped content but the parameter c increases with x. It indicates that the MnO6 octahedron increase the distortion with x content. With the x increase, their ferromagnetic property was depressed. The Neel temperature TN was depressed gradually from 138K to 89K, 95K and 85K at x=0.3 for T=Fe, Ni and Cr respectively. Their magnetoresistance MR is gradually enhanced for all doped system. It suggests that the introduce of disorder in B-site have an important effect on the magnetic exchange and magnetoresistance because of the weaken of the double-exchange (DE) interaction.

An 18-Membered Hexanuclear Manganese (MnN2)6 Metalladiazamacrocycle

2009 ◽  
Vol 64 (7) ◽  
pp. 779-783
Author(s):  
Qi-Feng Liang
Keyword(s):  
Solid State ◽  
Metal Ions ◽  
Exchange Interaction ◽  
Self Assembly ◽  
Antiferromagnetic Exchange ◽  
Antiferromagnetic Exchange Interaction

The macrocyclic hexanuclear manganese(III) 18-metallacrown-6, [Mn6(pmshz)6(DMF)4(C2H5- OH)2]·4DMF (1), where pmshz3− is N-propionyl-N'-5-methylsalicylhydrazide, has been synthesized by self-assembly and structurally characterized. The ring is formed by the succession of six structural moieties of the type [Mn(III)-N-N] with hydrazide N-N groups bridging the ring Mn ions. The ligand enforces the metal ions to form the stereochemistry of a configuration with alternate. . .ΔΛΔΛ. . .- type enantiomeric chiral units. The peripheral core ring is ~18.6 in diameter and ~12.4 Å in thickness. The title metallacrown exhibits photoluminescent properties in the solid state and a weak antiferromagnetic exchange interaction.

HREM Study of electron-induced surface radiation damage in ReO3

1991 ◽  
Vol 49 ◽  
pp. 636-637
Author(s):  
R. Ai ◽  
H.-J. Fan ◽  
L. D. Marks
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Carbon Film ◽  
Transition Metal Ions ◽  
Surface Radiation ◽  
Valence Transition ◽  
Electron Microscopes

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.

Synthesis, Spectral and Antimicrobial Investigation of 2-(Naphthalenel-ylamino)-2- Phenylacetonitrile and 1, 10-Phenanthroline with Five Divalent Transition Metal Ions

2019 ◽  
Vol 10 (01) ◽  
Author(s):  
Mohammed Al-Amery1 ◽  
Ashraf Saad Rasheed ◽  
Dina A. Najeeb
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Transition Metal Ions ◽  
Molar Conductance ◽  
Octahedral Geometry ◽  
Mixed Ligand ◽  
Gram Negative Bacteria ◽  
Magnetic Studies ◽  
Gram Positive Bacteria

Five new mixed ligand metal complexes have been synthesized by the reaction of divalent transition metal ions (Hg, Ni, Zn, Cu and Cd) with 2-(naphthalen-l-ylamino)-2-phenylacetonitrile (L1 ) and 1,10-phenanthroline (L2). The coordination likelihood of the two ligands toward metal ions has been suggested in the light of elemental analysis, UV-Vis spectra, FTIR, 1H-NMR, flam atomic absorption, molar conductance and magnetic studies. Results data suggest that the octahedral geometry for all the prepared complexes. Antibacterial examination of synthesized complexes in vitro was performed against four bacterias. Firstly, Gram-negative bacteria namely, Pseudomonas aerugin and Escherichia. Secondly, Gram-positive bacteria namely, Bacillus subtilis, Staphylococcuaurouss. Results data exhibit that the synthesized complexes exhibited more biological activity than tetracycline pharmaceutical.

Bond-length distributions for ions bonded to oxygen: Metalloids and post-transition metals

2017 ◽  
Author(s):  
Olivier Charles Gagné ◽  
Frank Christopher Hawthorne
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Metal Ions ◽  
Bond Length ◽  
Lone Pair ◽  
Transition Metal Ions ◽  
Oxygen Lone Pair

Bond-length distributions are examined for thirty-three configurations of the metalloid ions and fifty-six configurations of the post-transition-metal ions bonded to oxygen. Lone-pair stereoactivity is discussed.

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