Two trimeric tri-TiIV-substituted Keggin tungstogermanates based on tetrahedral linkers

Ren, Yuanhang; Liu, Shuxia; Cao, Ruige; Zhao, Xinyi; Cao, Jianfang; Gao, Chao-Ying

doi:10.1016/j.inoche.2008.08.009

Cited by 22 publications

(11 citation statements)

References 19 publications

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“…This can be attributed to formation of the {Ca 6 } cluster blocking one of the positions in the tetrapod and preventing the fourth trititanium(IV)-substituted Wells–Dawson subunit leading to the Ti 12 Tetramer from assembling. As related compounds, the tripod-shaped trimers based on A-site trititanium(IV)-substituted Keggin POM have been also reported. − …”

Section: Resultsmentioning

confidence: 99%

Synthesis and Molecular Structure of a Novel Compound Containing a Carbonate-Bridged Hexacalcium Cluster Cation Assembled on a Trimeric Trititanium(IV)-Substituted Wells–Dawson Polyoxometalate

et al. 2017

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A novel compound containing a hexacalcium cluster cation, one carbonate anion, and one calcium cation assembled on a trimeric trititanium(IV)-substituted Wells-Dawson polyoxometalate (POM), [{Ca(CO)(μ-OH)(OH)}(PWTiO)Ca(OH)] (CaTiTrimer), was obtained as the NaCa salt (NaCa-CaTiTrimer) by the reaction of calcium chloride with the monomeric trititanium(IV)-substituted Wells-Dawson POM species "[PWTiO(OH)]" (TiMonomer). TiMonomer was generated in situ under basic conditions from the separately prepared tetrameric species with bridging Ti(OH) groups and an encapsulated Cl ion, [{PWTiO(OH)}{μ-Ti(HO)}Cl] (TiTetramer). The NaCa salt of CaTiTrimer was characterized by complete elemental analysis, thermogravimetric (TG) and differential thermal analyses (DTA), FTIR, single-crystal X-ray structure analysis, and solution W andP NMR spectroscopy. X-ray crystallography revealed that the [Ca(CO)(μ-OH)(OH)] cluster cation was composed of six calcium cations linked by one μ-carbonato anion and one μ-OH anion. The cluster cation was assembled, together with one calcium ion, on a trimeric species composed of three tri-Ti(IV)-substituted Wells-Dawson subunits linked by Ti-O-Ti bonds. CaTiTrimer is an unprecedented POM species containing an alkaline-earth-metal cluster cation and is the first example of alkaline-earth-metal ions clustered around a titanium(IV)-substituted POM.

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Section: Resultsmentioning

confidence: 99%

Synthesis and Molecular Structure of a Novel Compound Containing a Carbonate-Bridged Hexacalcium Cluster Cation Assembled on a Trimeric Trititanium(IV)-Substituted Wells–Dawson Polyoxometalate

et al. 2017

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“…We can reveal only the molecular structure of the POM, but not the crystal structure. These features are too common in the POM crystallography [9,10,11,12,13,14,15,16,17,18]. …”

Section: Methodsmentioning

confidence: 99%

“…Site-selective substitution of the W VI atoms in POMs with Ti IV atoms is particularly interesting, because of formation of the multicenter active sites with corner- or edge-sharing TiO 6 octahedra and, also, generation of oligomeric species through Ti-O-Ti bonds [9,10,11,12,13,14,15,16,17,18]. A number of catalytic reactions of titanium(IV)-containing POMs have also been reported so far [19,20,21].…”

Section: Introductionmentioning

confidence: 99%

“…, [{γ-SiTi 2 W 10 O 36 (OH) 2 } 2 O 2 ] 8- [14] and [{γ-GeTi 2 W 10 O 36 (OH) 2 } 2 O 2 ] 8- [15], have been also prepared as a dimeric species, while di-Ti IV -1,5-substituted β-Keggin POM has been isolated as a tetrameric species, [{β-Ti 2 SiW 10 O 39 } 4 ] 24- [16]. In addition, the cyclic tri-Ti IV -substituted Keggin trimers such as [(α-Ti 3 PW 9 O 38 ) 3 (PO 4 )] 18- [17], [(α-Ti 3 SiW 9 O 37 OH) 3 (TiO 3 (OH 2 ) 3 )] 17- [17], and {K[(Ge(OH)O 3 ) (GeW 9 Ti 3 O 38 H 2 ) 3 ]} 14- [18] have been recently reported.…”

Section: Introductionmentioning

confidence: 99%

“…Polyoxometalates (POMs) are molecular metal-oxide clusters, which have attracted considerable attention in the fields of catalysis, medicine, surface science and materials science, since POMs are often considered as molecular analogues of metal oxides in term of structural analogy [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Site-selective substitution of the W VI atoms in POMs with Ti IV atoms is particularly interesting, because of formation of the multicenter active sites with corner- or edge-sharing TiO 6 octahedra and, also, generation of oligomeric species through Ti-O-Ti bonds [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. A number of catalytic reactions of titanium(IV)-containing POMs have also been reported so far [ 19 , 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

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Transformation of Tri-Titanium(IV)-Substituted α-Keggin Polyoxometalate (POM) into Tetra-Titanium(IV)-Substituted POMs : Reaction Products of Titanium(IV) Sulfate with the Dimeric Keggin POM Precursor under Acidic Conditions

et al. 2010

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Reaction products of titanium(IV) sulfate in HCl-acidic aqueous solution with the dimeric species linked through three intermolecular Ti-O-Ti bonds of the two tri-titanium(IV)-substituted α-Keggin polyoxometalate (POM) subunits are described. Two novel titanium(IV)-containing α-Keggin POMs were obtained under different conditions. One product was a dimeric species through two intermolecular Ti-O-Ti bonds of the two tetra-titanium(IV)-substituted α-Keggin POM subunits, i.e., [[{Ti(H2O)3}2(μ-O)](α-PW9Ti2O38)]26- (1). The other product was a monomeric α-Keggin species containing the tetra-titanium(IV) oxide cluster and two coordinated sulfate ions, i.e., [{Ti4(μ-O)3(SO4)2(H2O)8}(α-PW9O34)]3- (2). Molecular structures of 1 and 2 were also discussed based on host (lacunary site)-guest (titanium atom) chemistry.

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Chemistry of Group IV Metal Ion‐Containing Polyoxometalates

2010

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The chemistry of Group IV metal ion (TiIV, ZrIV and HfIV)‐containing polyoxometalates (POMs) is presented as a sharply focused microreview, introducing an aspect of our own research. The synthesis, structure, and solid/solution state behavior of the POMs, which are prepared by the reactions of various lacunary species of POMs with TiIV, ZrIV and HfIV atoms, are described in several sections, classified with Keggin and Dawson POM families. Because of the ionic radius of TiIV (0.75 Å), close to that of WVI (0.74 Å), the TiIV atom can fit nicely into the mono‐lacunary site of the POM, but ZrIV and HfIV atoms (0.85–0.86 Å), larger than TiIV atom, do not fit into the mono‐lacunary site of the POM. Thus, the mono‐lacunary site of the POM acts as the oxygen‐donor pentadentate ligand to the TiIV atom, whereas it acts as the tetradentate ligand to ZrIV and HfIV atoms. The TiIV atom in the POM takes on six‐coordinate geometry, whereas the ZrIV and HfIV atoms have higher coordination numbers (6, 7 and 8) due to their larger ionic radii. Consequently, most Ti‐substituted Keggin POMs are isolated as oligomers formed by corner‐sharing Ti–O–Ti bonds, whereas Zr/Hf‐containing Keggin/Dawson POMs are usually isolated as di‐, tri‐, tetra‐Zr/Hf cluster cations sandwiched between two lacunary POMs, the cluster cations of which are formed by edge‐sharing M(OH)2M (M = Zr, Hf) bonds. These compounds show quite different behavior under pH‐dependent conditions. The pH‐dependent interconversion between the dimeric and monomeric species of Ti‐substituted Dawson POMs is quite an opposite tendency from those of Zr/Hf‐containing Dawson POMs. The Ti‐substituted Dawson POM oligomers have a tendency to undergo base hydrolysis to give monomers, whereas the Zr/Hf‐containing Dawson POM oligomers have a tendency to undergo acid hydrolysis to provide monomers. In the Group IV metal ion‐containing POMs, the Zr/Hf atoms function very similarly to each other, but show quite different behavior from the Ti atom.

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Two trimeric tri-TiIV-substituted Keggin tungstogermanates based on tetrahedral linkers

Cited by 22 publications

References 19 publications

Synthesis and Molecular Structure of a Novel Compound Containing a Carbonate-Bridged Hexacalcium Cluster Cation Assembled on a Trimeric Trititanium(IV)-Substituted Wells–Dawson Polyoxometalate

Synthesis and Molecular Structure of a Novel Compound Containing a Carbonate-Bridged Hexacalcium Cluster Cation Assembled on a Trimeric Trititanium(IV)-Substituted Wells–Dawson Polyoxometalate

Transformation of Tri-Titanium(IV)-Substituted α-Keggin Polyoxometalate (POM) into Tetra-Titanium(IV)-Substituted POMs : Reaction Products of Titanium(IV) Sulfate with the Dimeric Keggin POM Precursor under Acidic Conditions

Chemistry of Group IV Metal Ion‐Containing Polyoxometalates

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