Structural Control on the Nanomolecular Scale: Self‐Assembly of the Polyoxotungstate Wheel [{β‐Ti₂SiW₁₀O₃₉}₄]²⁴⁻

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

“…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]. …”

“…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].…”

“…Di-Ti IV -substituted γ-Keggin silicotungstate and germanotungstate, i.e. , [{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.…”

Synthesis and characterization of a new dimeric polyoxometalate based on Anderson-type polyoxoanions and a trinuclear lanthanide coordination complex

“…An coworkers [10] and Kortz and coworkers [11,12]; a dimeric dumbbell-like compound constructed from Lindquist-type polyoxoanions has also been successfully synthesized [13]. In contrast, the role of Anderson-type polyoxoanions as the basic building block has not been so extensively studied.…”

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

“…In 2003, Kortz and coworkers characterized a series of Ti IV -substituted Wells-Dawson POMs based on the trivacant ½P 2 W 15 O 56 12À precursor [7]. Soon after that, they reported a large, wheel-shaped polyoxotungstate ½fb-Ti 2 SiW 10 O 39 g 4 24À , in which the di-Ti IV -substituted Keggin fragments self-assemble into a nano-size tetramer as a well-building block [8].…”