Direct Bromination of Keggin Fragments To Give [PW9O28Br6]3−: A Polyoxotungstate with a Hexabrominated Face

Errington, R. John; Wingad, Richard L.; Clegg, William; Elsegood, Mark R. J.

doi:10.1002/1521-3773(20001103)39:21<3884::aid-anie3884>3.0.co;2-m

Cited by 28 publications

(10 citation statements)

References 11 publications

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“…The X‐ray crystallographic analysis revealed that I Ge ‐OMe was essentially isostructural with I Si ‐OMe except for the heteroatom, and the X−O bond lengths (X=Si, 1.63–1.66 Å; X=Ge, 1.74–1.80 Å) were elongated by changing the heteroatom from Si to Ge due to the larger ionic radius of Ge 4+ . While several W 6+ oxo alkoxy complexes have been reported to date, I X ‐OMe (X=Si, Ge) were the first examples of X‐ray crystallographically characterized alkoxides of Keggin‐type lacunary POMs, to the best of our knowledge …”

Section: Resultsmentioning

confidence: 93%

Alkoxides of Trivacant Lacunary Polyoxometalates

Minato

Suzuki

Yamaguchi

et al. 2017

Chemistry A European J

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Lacunary polyoxometalates (POMs) are useful rigid multidentate inorganic ligands to construct multinuclear metal oxo clusters and inorganic-organic hybrid materials. However, the use of multivacant lacunary POMs often suffers from their undesired condensation reactions at the highly reactive vacant sites. Herein, the introduction of alkoxy protecting groups into the vacant sites of lacunary POMs in organic media is reported for the first time. By reacting organic solvent-soluble trivacant lacunary Keggin-type POMs with methanol, six methoxy groups were successfully introduced into the vacant sites, resulting in the formation of the alkoxides TBA [A-α-XW O (OCH ) ] (I -OMe; X=Si, Ge). These methoxy groups could protect the reactive vacant sites and suppress the undesired dimerization reaction into the corresponding α-Dawson-type POMs. Since the introduced monodentate methoxy groups could easily be dissociated by hydrolysis, I -OMe could be utilized as the precursor for the synthesis of metal-substituted POMs. In addition, by using pentaerythritol as the multidentate alkoxy ligand, the monomeric alkoxide TBA [A-α-SiW O {(OCH ) C(CH OH) } ] (I -PE) was successfully synthesized. In particular, these multidentate alkoxy groups showed high resistance against hydrolysis. Moreover, by reacting I -PE with trivacant lacunary Keggin-type POMs, the dimeric inorganic-organic-inorganic hybrid structures TBA H [(A-α-SiW O ){(OCH ) C(CH O) } (A-α-XW O )] (II -PE; X=Si, Ge) with the same or different heteroatoms (Si and Ge) were successfully synthesized.

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Section: Resultsmentioning

confidence: 93%

Alkoxides of Trivacant Lacunary Polyoxometalates

Minato

Suzuki

Yamaguchi

et al. 2017

Chemistry A European J

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“…[8][9][10][11] Rare instances involving p-block elements have also been reported in recent years. [12][13][14] Owing to rich substitutional chemistry and unique metal-oxygen framework, POMs exhibit unrivalled structural diversity and exceptional physical properties. The strong relevance with other disciplines, such as analytical chemistry, material science, biology, and nanotechnology has resulted in many potential applications, such as, catalysis, medicine, imaging, sensing, and multifunctional materials.…”

Section: Introductionmentioning

confidence: 99%

Surfactant-encapsulated polyoxometalate building blocks: controlled assembly and their catalytic properties

2012

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Polyoxometalates (POMs) are discrete anionic metal-oxide nanoclusters which exhibit unrivalled structural diversity, exceptional physical properties, and have many potential applications. Nonetheless, possessing high crystalline energy and hydrophilic nature, the assembly of POM clusters into rationally design architectures has been a long-standing bottleneck for their ultimate use in advanced materials and devices. To confront this challenge, both covalent and non-covalent modifications of POM nanoclusters are increasingly considered. This perspective reviews recent progress in the assembly of non-covalently modified surfactant-encapsulated POM nanoclusters with particular emphasis on our research work. The described solution-based assembly approach provides an excellent control on size, shape, and stability of the assembly structures. By effective exploitation of non-covalent interactions between the POM hybrid nanobuilding blocks, several unprecedented assembly structures including disks, cones, tubes, fullerene-like spheres, multiple shape flowers, wires, and thin films can be achieved. The assembly structures are highly robust and tunable in terms of size and shape and can act as hosts for guest nanomaterials to develop composite materials of combinatorial properties. In the last section of this manuscript, we present the catalytic properties of the assembly structures and their remote controlled manipulation in the reaction system.

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“…120 A six-membered ring of MoO 6 octahedra is found within [Mo 6 O 18 (O 3 POPO 3 )(H 2 O) 4 ]42 , a species which may be viewed as the first structurally characterised intermediate in the molybdate-catalysed hydrolysis of pyrophosphate 121. Larger species include [W 9 O 28 Br 6 P] 3-(which bears a fully brominated face),122 a new structural class of mixed valence heteropolytungstates of formula [W 20 O 62 -H y (XO 4 )] n2 (wherein X = H 2 , B or Si),123 and [{Mo 15 O 45 (P 2 O 7 )} 2 ] 82 124.…”

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confidence: 99%