Metal—Metal Exchange Coupling

ChemInform ◽  
2004 ◽  
Vol 35 (23) ◽  
Author(s):  
R. J. Crutchley
Keyword(s):  
Exchange Coupling ◽  
Metal Exchange ◽  
Metal Metal

[(Cp*)(dppe)Fe(III)−]+Units Bridged through 1,3-Diethynylbenzene and 1,3,5-Triethynylbenzene Spacers: Ferromagnetic Metal−Metal Exchange Interaction

1998 ◽  
Vol 17 (25) ◽  
pp. 5569-5579 ◽  
Author(s):  
Tania Weyland ◽  
Karine Costuas ◽  
Alain Mari ◽  
Jean-François Halet ◽  
Claude Lapinte
Keyword(s):  
Exchange Interaction ◽  
Ferromagnetic Metal ◽  
Metal Exchange ◽  
Metal Metal

scholarly journals Upgrading the Hydrogen Storage of MOF-5 by Post-Synthetic Exchange with Divalent Metal Ions

2021 ◽  
Vol 11 (24) ◽  
pp. 11687
Author(s):  
Abdul Malik P. Peedikakkal ◽  
Isam H. Aljundi
Keyword(s):  
Metal Ions ◽  
Adsorption Isotherms ◽  
Metal Organic Frameworks ◽  
Hydrogen Uptake ◽  
Metal Exchange ◽  
Mixed Metal ◽  
H2 Adsorption ◽  
Hydrogen Molecules ◽  
Metal Metal ◽  
Metal Organic

In metal-organic frameworks (MOFs), mixed-metal clusters have the opportunity to adsorb hydrogen molecules due to a greater charge density of the metal. Such interactions may subsequently enhance the gravimetric uptake of hydrogen. However, only a few papers have explored the ability of mixed-metal MOFs to increase hydrogen uptake. The present work reveals the preparation of mixed metal metal-organic frameworks M-MOF-5 (where M = Ni2+, Co2+, and Fe2+) (where MOF-5 designates MOFs such as Zn2+ and 1,4-benzenedicarboxylic acid ligand) using the post-synthetic exchange (PSE) technique. Powder X-ray diffraction patterns and scanning electron microscopy images indicate the presence of crystalline phases after metal exchange, and the inductively coupled plasma–mass spectroscopy analysis confirmed the exchange of metals by means of the PSE technique. The nitrogen adsorption isotherms established the production of microporous M-MOF-5. Although the additional metal ions decreased the surface area, the exchanged materials displayed unique features in the gravimetric uptake of hydrogen. The parent MOF-5 and the metal exchanged materials (Ni-MOF-5, Co-MOF-5, and Fe-MOF-5) demonstrated hydrogen capacities of 1.46, 1.53, 1.53, and 0.99 wt.%, respectively. The metal-exchanged Ni-MOF-5 and Co-MOF-5 revealed slightly higher H2 uptake in comparison with MOF-5; however, the Fe-MOF-5 showed a decrease in uptake due to partial discrete complex formation (discrete complexes with one or more metal ions) with less crystalline nature. The Sips model was found to be excellent in describing the H2 adsorption isotherms with a correlation coefficient ≅ 1. The unique hydrogen uptakes of Ni− and Co-MOF-5 shown in this study pave the way for further improvement in hydrogen uptake.

Heteronuclear cluster compounds

1982 ◽  
Vol 308 (1501) ◽  
pp. 17-26 ◽  
Keyword(s):  
Electron Distribution ◽  
Ligand Substitution ◽  
Cluster Compounds ◽  
Cluster Core ◽  
Metal Exchange ◽  
Basic Cluster ◽  
Metal Metal ◽  
Physical Phenomena ◽  
Metal Bonds ◽  
Heteronuclear Cluster

Several designed syntheses have been developed for heteronuclear organometallic cluster compounds. They involve step-by-step construction, fragment combination and metal exchange. The compounds obtained permit the study of the physical phenomena of electron distribution and chirality in the cluster frameworks. Prominent chemical phenomena are the weakness of some metal-metal bonds, the unsaturated nature of some clusters, and polarity due to heteronuclearity. They permit the study of basic cluster reactions like the unfolding of the clusters with nucleophiles, the addition of substrates without gross changes in the cluster framework and without ligand substitution, the capping of clusters by suitable ligands, and the reaction of different substrates at different locations in the cluster core.

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