27Al NMR study of the effect of aqueous and methanolic media on the distribution of tetraphenylammonium aluminosilicate species

Goudarzi, Nasser

doi:10.1134/s0022476615020079

Cited by 1 publication

(3 citation statements)

References 37 publications

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“…Molecular metal-oxo clusters resemble discrete units of bulk metal oxide materials and serve as preassembled building blocks in nature and in synthesis. − Stable isolatable clusters that possess only ligands derived from water (H 2 O, OH – , and O 2– ) are generally limited to the groups 5 & 6 polyoxometalates (polyanions) and group 13 polyoxocations. − A few additional exceptions include a polycationic Hf tetramer and anionic silicate and aluminosilicate octamers. − By employing capping organic ligands such as carboxylates and amines, metal-oxo clusters of any metal cation can be isolated. , These metals include low-valent transition metals with partially filled d orbital and lanthanides . However, we have limited ability to manipulate or exploit these ligated clusters in solution, because they generally have poor solubility, and the metal cations are not accessible.…”

Section: Introductionmentioning

confidence: 99%

“…With the formula [FeO 4 Fe 12 F 24 (OMe) 12 ] 5− , this cluster has no exterior aqua ligands nor known aqueous chemistry, because the methoxy ligands are unstable in water. More recently, we synthesized the α-Keggin cluster [Bi 6 FeO 4 Fe 12 O 12 (OH) 12 (CCl 3 COO) 12 ] 1+ (Kegg-3). 21 Oxo and hydroxyl ligands bridge the iron centers, while trichloroacetate caps the irons in the terminal position.…”

Section: ■ Introductionmentioning

confidence: 99%

“…T h e c l u s t e r f o r m u l a t e d a s [ B i 6 F e O 4 F e 1 2 O 1 2 -(OH) 12 (CF 3 COO) 10 (H 2 O) 2 ] 3+ (Kegg-1) has structural differences from Kegg-3, most notably (1) two terminal acetate (TFA) ligands are replaced with water, and (2) disorder in oxo and hydroxyl ligands leads to different Fe−Fe distances within the cluster. The latter feature influences magnetic behavior and is the subject of a concurrent publication.…”

Section: ■ Introductionmentioning

confidence: 99%

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Chemical Stabilization and Electrochemical Destabilization of the Iron Keggin Ion in Water

et al. 2016

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The iron Keggin ion is identified as a structural building block in both magnetite and ferrihydrite, two important iron oxide phases in nature and in technology. Discrete molecular forms of the iron Keggin ion that can be both manipulated in water and chemically converted to the related metal oxides are important for understanding growth mechanisms, in particular, nonclassical nucleation in which cluster building units are preserved in the aggregation and condensation processes. Here we describe two iron Keggin ion structures, formulated as [Bi6FeO4Fe12O12(OH)12(CF3COO)10(H2O)2]3+ (Kegg-1) and [Bi6FeO4Fe12O12(OH)12(CF3COO)12]1+ (Kegg-2). Experimental and simulated X-ray scattering studies show indefinite stability of these clusters in water from pH 1–3. The tridecameric iron Keggin-ion core is protected from hydrolysis by a synergistic effect of the capping Bi3+ cations and the trifluoroacetate ligands that, respectively, bond to the iron and bridge to the bismuth. By introducing electrons to the aqueous solution of clusters, we achieve complete separation of bismuth from the cluster, and the iron Keggin ion rapidly converts to magnetite and/or ferrihydrite, depending on the mechanism of reduction. In this strategy, we take advantage of the easily accessible reduction potential and crystallization energy of bismuth. Reduction was executed in bulk by chemical means, by voltammetry, and by secondary effects of transmission electron microscopy imaging of solutions. Prior, we showed a less stable analogue of the iron Keggin cluster converted to ferrihydrite simply upon dissolution. The prior and currently studied clusters with a range of reactivity provide a chemical system to study molecular cluster to metal oxide conversion processes in detail.

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