scholarly journals Spin Cross-Over (SCO) Complex Based on Unsymmetrical Functionalized Triazacyclononane Ligand: Structural Characterization and Magnetic Properties

2019 ◽  
Vol 5 (1) ◽  
pp. 19 ◽  
Author(s):  
Merzouk Halit ◽  
Mélissa Roger ◽  
Véronique Patinec ◽  
Said Yefsah ◽  
Carlos Gómez-García ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thermal Decomposition ◽  
Magnetic Properties ◽  
Nmr Spectroscopy ◽  
Functional Groups ◽  
Structural Characterization ◽  
Spin Crossover ◽  
Magnetic Studies ◽  
Dsc Measurements ◽  
Hexadentate Ligand

The unsymmetrical ligand 1-(2-aminophenyl)-4,7-bis(pyridin-2-ylmethyl)-1,4,7-triazacyclononane (L6) has been prepared and characterized by NMR spectroscopy. The L6 ligand is based on the triazamacrocycle (tacn) ring that is functionalized by two flexible 2-pyridylmethyl and one rigid 2-aminophenyl groups. Reaction of this ligand with Fe(ClO4)2·xH2O led to the complex [Fe(L6)](ClO4)2 (1), which was characterized as the first Fe(II) complex based on the unsymmetrical N-functionalized tacn ligand. The crystal structure revealed a discrete monomeric [FeL6]2+ entity in which the unsymmetrical N-functionalized triazacyclononane molecule (L6) acts as hexadentate ligand. As observed in the few parent examples that are based on the symmetrical N-functionalized tacn ligands, the triazacyclononane ring is facially coordinated and the N-donor atoms of the three functional groups (two pyridine and one aniline groups) are disposed in the same side of the tacn ring, leading to a distorted FeN6 environment. The magnetic studies of 1 revealed the presence of an incomplete spin crossover (SCO) transition above 425 K, whose progress would be prevented by a very exothermic thermal decomposition at ca. 472 K, as shown by thermogravimetric and DSC measurements.

Nd7,33Ta8O28CI6 — ein Zwischenprodukt des thermischen Abbaus von Nd2Ta2O7Cl2: Präparation, Struktur und magnetische Eigenschaften / Nd7,33Ta8O28Cl6 — an Intermediate Product of the Thermal Decomposition of Nd2Ta2O7Cl2: Preparation, Crystal Structure and Magnetic Properties

1988 ◽  
Vol 43 (12) ◽  
pp. 1567-1574 ◽  
Author(s):  
U. Schaffrath ◽  
R. Gruehn
Keyword(s):  
Crystal Structure ◽  
Thermal Decomposition ◽  
Magnetic Properties ◽  
Calculated Data ◽  
Chemical Transport ◽  
Structure Type ◽  
Magnetic Susceptibilities ◽  
Relationship Of ◽  
The Relationship ◽  
Preparative Route

Abstract Single crystals of the new oxochlorotantalate Nd7.33Ta8O28Cl6, could be obtained only by chemical transport reactions (T2 → T1; T2 - 1000 °C, T, = 900 °C) with mixtures of Cl2/TaCl5 as transport agent. NdTaO4 was chosen as the starting material. A direct preparative route to Nd7.33Ta8O28Cl6 from binary and ternary components, however, was not successful. Nd7.33Ta8O28Cl6 , crystallizes in the space group Cmmm with a = 10.3381(8) Å, b = 18.865(1) Å, c - 3.9152(3) A; Z = 1. The structure was refined to R - 4.42%, R w = 2.76%. Main building units are pairs of edge-sharing TaO6 -octahedra which are connected with threefold capped trigonal prisms around Nd. Especially remarkable is one Nd position with an occupation factor of 0.833. The relationship of this new structure type with Nd2Ta2O7Cl2 is considered. Furthermore, we have measured the magnetic susceptibilities of both Nd-compounds in a temperature range from 3,6 to 251,3 K. The results are compared with calculated data.

A novel hybrid iron fluoride based on 8-hydroxyquinoline: Crystal structure, thermal decomposition, spectroscopic characterization, and magnetic properties

2019 ◽  
Vol 496 ◽  
pp. 119033
Author(s):  
Oussama Guesmi ◽  
Mohammed S.M. Abdelbaky ◽  
David Martínez-Blanco ◽  
Lilia Ktari ◽  
Santiago García-Granda ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thermal Decomposition ◽  
Magnetic Properties ◽  
Spectroscopic Characterization ◽  
Iron Fluoride

Effect of annealing temperature on structural and magnetic properties of strontium hexaferrite nanoparticles synthesized by sol–gel auto-combustion method

2015 ◽  
Vol 29 (27) ◽  
pp. 1550190 ◽  
Author(s):  
Ebrahim Roohani ◽  
Hadi Arabi ◽  
Reza Sarhaddi ◽  
Saeedeh Sudkhah ◽  
Ameneh Shabani
Keyword(s):  
Crystal Structure ◽  
Thermal Decomposition ◽  
Magnetic Properties ◽  
Thermogravimetric Analysis ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Combustion Method ◽  
Strontium Hexaferrite ◽  
Auto Combustion ◽  
Ft Ir

In this paper, strontium hexaferrite nanoparticles were synthesized by the sol–gel auto-combustion method. Effect of annealing temperature on crystal structure, morphology and magnetic properties of nanoparticles was investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). Also, the thermal decomposition of as-synthesized powdered samples has been studied by thermogravimetric analysis (TGA). The XRD patterns confirmed the formation of single phase M-type hexagonal crystal structure for powders annealed above 950[Formula: see text]C, whereas the presence of hematite ([Formula: see text]-Fe2O3) as secondary phase was also observed for sample annealed at 900[Formula: see text]C. Furthermore, the crystallinity along with the crystallite size were augmented with annealing temperature. Comparison of the FT-IR spectra of the samples before and after annealing treatment showed the existence of metal–oxygen stretching modes after annealing. The thermogravimetric analysis confirmed the thermal decomposition of as-burnt powders happened in three-stage degradation process. The TEM images showed the nanoparticles like hexagonal-shaped platelets as the size of nanoparticles increases by increasing the annealing temperature. With increasing annealing temperature, the magnetic saturation and the coercivity were increased to the maximum value of 74.26 emu/g and 5.67 kOe for sample annealed at 1000[Formula: see text]C and then decreased.

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