[e-PMo12O36(OH)4{La(H2O)4}4]5+: The First e-PMo12O40 Keggin Ion and Its Association with the Two-Electron-Reduced α-PMo12O40 Isomer

Abstract

Polyoxometalates, often considered as soluble metal oxides, have long attracted interest because of their large field of applications, especially in the domain of heterogeneous catalysis. [1] The famous Keggin ion [a-PMo 12 O 40 ] 3À was isolated nearly 200 years ago. Isomerization formally results from successive 608 rotations of the four basic Mo 3 O 13 groups. Although the five isomers a, b, g, d, and e of the Keggin structure have been postulated, only the a [2] and b [3] isomers of PMo 12 O 40 have been structurally characterized to date. However, the e-Keggin structure has been encountered in related compounds which are either polyoxocations, with an Al III 12 core and a central tetrahedral Al III , [4] Ga III , or Ge III[5] center, or polyoxoions with Mo V 12 and V V 12 cores. In the case of Mo and V derivatives, [6] the highly negatively charged structure is stabilized by electrophilic capping groups. The Mo V 12 O 40 skeleton has been crystallographically characterized in four polyoxometalates: the [(C 5 Me 5 Rh III ) 8 -(Mo V 12 O 36 )(Mo VI O 4 )] 2 complex [7] has a central Mo VI O 4 2À

Dehydrogenative coupling of 2,2 ′ -bipyridine: hydrothermal synthesis and crystal structure of a novel polyoxovanadate decorated with the 2,2 ′ ;6 ′ ,2″;6″,2 ′′′ -quaterpyridine ligand

“…Organic-inorganic hybrid materials have been attracting extensive interest owing to their potential applications in catalysis, electron conductivity, magnetism and photochemistry, as well as their interesting structural features [1][2][3][4][5][6][7][8]. By incorporating organic and inorganic counterparts into a single structure, the functionality of organic-inorganic hybrid materials can be multiplied from both organic linker molecules and inorganic species [9][10][11].…”

Jenseits von Ladungsausgleich: Gegenkationen in der Polyoxometallat‐Chemie

“…Weitere Beweise für die multifunktionelle Rolle hochvalenter Metallkationen konnten z. B. durch Isolierung der gemischtvalenten Mo‐basierten ϵ‐Keggin‐Spezies [{La(H 2 O) 4 } 4 PMo V 8 Mo VI 4 O 36 (OH) 4 ] 5+ ( {La 4 Mo 12 } ) geliefert werden . Die Spezies ist strukturell eng verwandt mit {Bi 4 V 13 } und hat vier La 3+ ‐Kationen, die durch je drei Mo‐O‐La‐Bindungen an die trigonalen Vakanzen des ϵ‐Keggin‐Clusters gebunden sind.…”

Computational exploration of metal–organic frameworks: examples of advances in crystal structure predictions and electronic structure tuning

“…[37] Having the topology of zeolites in mind, the design strategy chosen above required the search for a suitable cationic POM, together with a suitable bidendate organic linker. For the POM, the authors turned to the recently developed family of compounds based on the 1-Keggin isomer of the reduced {PMo 12 O 40 } anion [38] and chose its Zn(II) derivative, denoted by 1-Zn, due to the likelihood of the external Zn coordination sites to adopt a tetrahedral arrangement and react with bifunctional linkers. Regarding the linker, we chose the rigid benzene dicarboxylate (BDC) to form the targeted POM -Zn -LZn -POM linkages, as BDC is a common linker in MOFs.…”