Effects of substitution, solvent andpH on magnetic exchange interactions in SOD model systems: ESR, electrochemical and single crystal x-ray studies

1996 ◽  
Vol 108 (3) ◽  
pp. 307-307
Author(s):  
P S Subramanian ◽  
D Srinivas ◽  
Mohan M Bhadbhade ◽  
M Velayuthum ◽  
S Subramanian
Keyword(s):  
Single Crystal ◽  
Exchange Interactions ◽  
Model Systems ◽  
Magnetic Exchange ◽  
X Ray

Structural analysis of Gd6FeBi2 from single-crystal X-ray diffraction methods and electronic structure calculations

2019 ◽  
Vol 75 (5) ◽  
pp. 562-567 ◽  
Author(s):  
Jiliang Zhang ◽  
Yong-Mook Kang ◽  
Guangcun Shan ◽  
Svilen Bobev
Keyword(s):  
Electronic Structure ◽  
Single Crystal ◽  
First Principles ◽  
Earth Metal ◽  
Magnetic Ordering ◽  
Additional Contribution ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
Magnetic Exchange ◽  
X Ray

The crystal structure of the gadolinium iron bismuthide Gd6FeBi2 has been characterized by single-crystal X-ray diffraction data and analyzed in detail using first-principles calculations. The structure is isotypic with the Zr6CoAl2 structure, which is a variant of the ZrNiAl structure and its binary prototype Fe2P (Pearson code hP9, Wyckoff sequence g f d a). As such, the structure is best viewed as an array of tricapped trigonal prisms of Gd atoms centered alternately by Fe and Bi. The magnetic-ordering temperature of this compound (ca 350 K) is much higher than that of other rare-earth metal-rich phases with the same or related structures. It is also higher than the ordering temperature of many other Gd-rich ternary phases, where the magnetic exchange is typically governed by Ruderman–Kittel–Kasuya–Yosida (RKKY) interactions. First-principles calculations reveal a larger than expected Gd magnetic moment, with the additional contribution arising from the Gd 5d electrons. The electronic structure analysis suggests strong Gd 5d–Fe 3d hybridization to be the cause of this effect, rather than weak interactions between Gd and Bi. These details are of importance for understanding the magnetic response and explaining the high ordering temperature in this material.

scholarly journals Exploiting Host-Guest Chemistry to Manipulate Magnetic Interactions in Metallosupramolecular M4L6 Tetrahedral Cages

2021 ◽  
Author(s):  
Aaron Scott ◽  
Julia Vallejo ◽  
Arup Sarkar ◽  
Lucy Smythe ◽  
Emma Regincós Martí ◽  
...  
Keyword(s):  
Single Crystal ◽  
Self Assembly ◽  
Close Agreement ◽  
Exchange Interactions ◽  
Magnetic Interactions ◽  
Magnetic Exchange ◽  
Guest Molecules ◽  
Space Groups ◽  
Comparable Magnitude ◽  
Spin Densities

<p>Reaction of Ni(OTf)<sub>2</sub> with the bisbidentate quaterpyridine ligand L results in the self-assembly of a tetrahedral, paramagnetic cage [Ni<sup>II</sup><sub>4</sub>L<sub>6</sub>]<sup>8+</sup>. By selectively exchanging the bound triflate from [OTfÌNi<sup>II</sup><sub>4</sub>L<sub>6</sub>](OTf)<sub>7</sub> (<b>1</b>), we have been able to prepare a series of host-guest complexes that feature an encapsulated paramagnetic tetrahalometallate ion inside this paramagnetic host giving [M<sup>II</sup>X<sub>4</sub>ÌNi<sup>II</sup><sub>4</sub>L<sub>6</sub>](OTf)<sub>6</sub>, where M<sup>II</sup>X<sub>4</sub><sup>2− </sup>= MnCl<sub>4</sub><sup>2−</sup> (<b>2</b>), CoCl<sub>4</sub><sup>2−</sup> (<b>5</b>), CoBr<sub>4</sub><sup>2−</sup> (<b>6</b>), NiCl<sub>4</sub><sup>2−</sup> (<b>7</b>), CuBr<sub>4</sub><sup>2−</sup> (<b>8</b>) or [M<sup>III</sup>X<sub>4</sub>ÌNi<sup>II</sup><sub>4</sub>L<sub>6</sub>](OTf)<sub>7</sub>, where M<sup>III</sup>X<sub>4</sub><sup>−</sup> = FeCl<sub>4</sub><sup>−</sup> (<b>3</b>), FeBr<sub>4</sub><sup>−</sup> (<b>4</b>). Triflate-to-tetrahalometallate exchange occurs in solution and can also be accomplished through single-crystal-to-single-crystal transformations. Host-guest complexes <b>1</b>-<b>8</b> all crystallise as homochiral racemates in monoclinic space groups, wherein the four {NiN<sub>6</sub>} vertex within a single Ni<sub>4</sub>L<sub>6</sub> unit possess the same Δ or Λ stereochemistry. Magnetic susceptibility and magnetisation data show that the magnetic exchange between metal ions in the host [Ni<sup>II</sup><sub>4</sub>] complex, and between the host and the MX<sub>4</sub><sup>n-</sup> guest, are of comparable magnitude and antiferromagnetic in nature. Theoretically derived values for the magnetic exchange are in close agreement with experiment, revealing that large spin densities on the electronegative X-atoms of particular {MX<sub>4</sub>}<sup>n−</sup> guest molecules leads to stronger host-guest magnetic exchange interactions. </p>

scholarly journals Exploiting Host-Guest Chemistry to Manipulate Magnetic Interactions in Metallosupramolecular M4L6 Tetrahedral Cages

2021 ◽  
Author(s):  
Aaron Scott ◽  
Julia Vallejo ◽  
Arup Sarkar ◽  
Lucy Smythe ◽  
Emma Regincós Martí ◽  
...  
Keyword(s):  
Single Crystal ◽  
Self Assembly ◽  
Close Agreement ◽  
Exchange Interactions ◽  
Magnetic Interactions ◽  
Magnetic Exchange ◽  
Guest Molecules ◽  
Space Groups ◽  
Comparable Magnitude ◽  
Spin Densities

<p>Reaction of Ni(OTf)<sub>2</sub> with the bisbidentate quaterpyridine ligand L results in the self-assembly of a tetrahedral, paramagnetic cage [Ni<sup>II</sup><sub>4</sub>L<sub>6</sub>]<sup>8+</sup>. By selectively exchanging the bound triflate from [OTfÌNi<sup>II</sup><sub>4</sub>L<sub>6</sub>](OTf)<sub>7</sub> (<b>1</b>), we have been able to prepare a series of host-guest complexes that feature an encapsulated paramagnetic tetrahalometallate ion inside this paramagnetic host giving [M<sup>II</sup>X<sub>4</sub>ÌNi<sup>II</sup><sub>4</sub>L<sub>6</sub>](OTf)<sub>6</sub>, where M<sup>II</sup>X<sub>4</sub><sup>2− </sup>= MnCl<sub>4</sub><sup>2−</sup> (<b>2</b>), CoCl<sub>4</sub><sup>2−</sup> (<b>5</b>), CoBr<sub>4</sub><sup>2−</sup> (<b>6</b>), NiCl<sub>4</sub><sup>2−</sup> (<b>7</b>), CuBr<sub>4</sub><sup>2−</sup> (<b>8</b>) or [M<sup>III</sup>X<sub>4</sub>ÌNi<sup>II</sup><sub>4</sub>L<sub>6</sub>](OTf)<sub>7</sub>, where M<sup>III</sup>X<sub>4</sub><sup>−</sup> = FeCl<sub>4</sub><sup>−</sup> (<b>3</b>), FeBr<sub>4</sub><sup>−</sup> (<b>4</b>). Triflate-to-tetrahalometallate exchange occurs in solution and can also be accomplished through single-crystal-to-single-crystal transformations. Host-guest complexes <b>1</b>-<b>8</b> all crystallise as homochiral racemates in monoclinic space groups, wherein the four {NiN<sub>6</sub>} vertex within a single Ni<sub>4</sub>L<sub>6</sub> unit possess the same Δ or Λ stereochemistry. Magnetic susceptibility and magnetisation data show that the magnetic exchange between metal ions in the host [Ni<sup>II</sup><sub>4</sub>] complex, and between the host and the MX<sub>4</sub><sup>n-</sup> guest, are of comparable magnitude and antiferromagnetic in nature. Theoretically derived values for the magnetic exchange are in close agreement with experiment, revealing that large spin densities on the electronegative X-atoms of particular {MX<sub>4</sub>}<sup>n−</sup> guest molecules leads to stronger host-guest magnetic exchange interactions. </p>

A Dynamically Nanoporous Metal-Organic Framework Functional Properties

2011 ◽  
Vol 239-242 ◽  
pp. 3150-3155 ◽  
Author(s):  
Xing Huang ◽  
Li Jun Jiang ◽  
Mao Lin Hu ◽  
Xin Hua Li
Keyword(s):  
Metal Organic Framework ◽  
Exchange Interactions ◽  
Gas Storage ◽  
Magnetic Exchange ◽  
X Ray ◽  
Crystal Transformation ◽  
Nanoporous Metal ◽  
Metal Organic ◽  
Coordination Framework ◽  
Single Crystal Analysis

3D nanoporous coordination framework [Ni2(nic)4(H2O)]n(nic=Nicotinic acid) was obtained hydrothermally from a mixture of NiCl2.6H2O and 3-cyanopyridine. X-ray single crystal analysis revealed that it consists of “mushroom-shaped” channels along a axis suitable for gas storage. N2-adsorption studies at 77 K revealed a Langmuir surface area of 200 m2/g and a pore volume of 0.12 cm3/g. The compound shows dynamic dehydration and rehydration behaviors with the formation of 0D coordination [Ni(nic)2(H2O)4], accompanied by crystal-to-crystal transformation. The structural transformation significantly changes the character of magnetic exchange interactions and gas storage.

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