Self‐Assembly of Supramolecular Polyoxometalates: The Compact, Water‐Soluble Heteropolytungstate Anion [AsCe(H₂O)₃₆W₁₄₈O₅₂₄]⁷⁶⁻

Abstract

COMMUNICATIONS Experimental Section16. To a solution of 15 (92 mg, 0.072 mmol) in chloroform/methanol 112 (80 mL) was added 1 M NaOCHJCH,OH (2 mL, 2 mmol). This was held at reflux for 4 h under argon in the dark. After removal of the solvent and drying, the residue was purified by preparative thin layer chromatography (neutral Al,O,, CH,Cl,, exclusionoflight;R,of 16isabout 1).Afterdryingat40"C/10~2Torr,64mgof 16was obtained (0.056 mmol, 77%). 17: All reactions were carried out in a glove box under argon. Iron complex 15 (0.56 mg. 4 x lo-' mol) and crown complex 18 (16 mg, 21.2 x mol) were dissolved in DMSO (4 mL) and allowed to react for 30 min. After the addition of a DlMSYLNa solution (31 -44 mg NaH) and a further 30 min reaction, the volume of the solution was increased to 20 mL, and CO was bubbled through the solution. Epoxidation of cis-stilbene (under argon with light exclusion): cis-stilbene (450 mg, 2.5 rnmol), 16 (28.8 mg, 0.025 mmol), and iodosylbenzene (55 mg, 0.25 mmol) were stirred in CH,Cl, (6 mL) for 5 h at room temperature. After removal of the solvent (30 'C, 300 mbar), the residue was taken up in 200 rnL n-pentane, and the catalyst removed by filtration (25-30% 16 was recovered unchanged); the solvent was then removed (30°C 300 mbar). Quantitative analysis of the reaction products was carried out by 'H NMR spectroscopy with 4-chlorotoluene as internal standard.

Hybrid Host–Guest Complexes: Directing the Supramolecular Structure through Secondary Host–Guest Interactions

“…[1] A vast range of structural types is accessible with nuclearities ranging from 6 to 368 metal centres. Tungsten [2] and molybdenum-based [3] systems in particular have been subjected to a vast number of studies due to their attractive electronic and molecular properties, making these clusters ideal candidates for applications in catalysis, [5,6] magnetism, [7,8] electron-transfer processes, [9,10] materials science [11][12][13] and medicine. [14,15] Typically, the synthesis of polyoxometalates employs "one-pot" reactions in which a multitude of parameters, such as acidity, ionic strength of the solvent, temperature and pressure, dramatically affect the final product.…”

Development of a Building Block Strategy To Access Gigantic Nanoscale Heteropolyoxotungstates by Using SeO32− as a Template Linker

“…[17][18][19] In contrast, the exploration of high nuclearity polyoxotungstate clusters has yielded different results with somewhat lower nuclearity isopolyoxotungstates: {W 34 } and {W 36 }, [20,21] and has been more limited since tungsten-based building blocks with pentagonal geometries have only very recently been accessed. [22][23] , [25,26] and most recently the synthesis of the spectacular {W 72 Fe 30 } "Keplerate". [23] Herein, we demonstrate that it is possible to generate gigantic heteropolyoxotungstates by utilizing the SeO 3 2À heteroanion.…”

“…In addition, the excess SeO 3 2À plays the vital role of "assistant" template and links two corner-sharing {WO 6 } linkers between two {W 9 Se} units on one side in the {W 22 Se 2 } unit and thus forms a new type of building block: {W 25 Se 3 }. To assemble the overall {W 100 Se 16 } cluster, the four {W 25 Se 3 } subunits are linked by another four SeO 3 2À groups in a "head-to-tail" mode. In the assembly process, the "head" linker SeO 3 2À is always connected to the {WO 6 } "tail" from another building unit.…”

“…The cluster is constructed from eight Se IV linkers and four equal fragments that can be assigned as {W 25 Se 2 }, which are derived from the aforementioned {W 22 Se 2 } fragment. The half-open cavity of {W 22 Se 2 } is occupied by three corner-shared {WO 6 } units and a K + ion, which results in the formation of a {W 25 Se 2 K} subunit (see Figure 5).…”

Synthesis and Characterization of 8-Yttrium(III)-Containing 81-Tungsto-8-Arsenate(III), [Y8(CH3COO)(H2O)18(As2W19O68)4(W2O6)2(WO4)]43−

“…In addition, the larger size of these lanthanide ions usually restricts their full incorporation into the lacunary POM sites. Such coordination behavior renders lanthanide ions frequently as linkers of two or more lacunary POM units, forming large structures [18][19][20][21][22][23][25][26][27]. Yttrium is formally not a lanthanide, but can be considered as a pseudolanthanide, due to its comparable size and coordination number.…”