pH-Controlled One Pot Syntheses of Giant Mo₂O₂S₂-Containing Seleno-Tungstate Architectures

Abstract

Self-assembly reactions of NaWO, SeO/SeO, and [MoO(μ-S)(HO)] give, depending on the pH value, two new large polyoxometalate complexes: i.e., [(γ-SeWO)(MoO(μ-S)(HO))] (1) isolated at pH 3.5 and [(γ-SeWO)(WO(HO))(WO)(WO)(MoO(μ-S)(HO))(MoO(μ-S)(SeO))] (2) isolated at pH 2. Both compounds were characterized in the solid state by single-crystal X-ray diffraction, EDX, elemental analysis, TGA, and FT-IR and in solution by ESI-MS and NMR.

Unprecedented Selenium and Lanthanide Simultaneously Bridging Selenotungstate Aggregates Stabilized by Four Tetra‐vacant Dawson‐like {Se2W14} Units

“…Furthermore, we have also explored the effect of the molar ratio of Na 2 WO 4 · 2H 2 O/Na 2 SeO 3 on the formation of 1-6.I np reviousr eports, the molar ratio of Se/W was varied in the range 0.06-0.70. We reported the lowest molar ratio of Se/W (0.06) in 2015, [14a] and the highest molarratio of Se/W (0.70) was reported in 2010 by Cronin et al [3] In this paper,wefind when the molar ratio of Se/W varies in the range 1.40-2.50, 1-6 can be obtained, which is three times the reportedhighest ratio (0.70) and thirty-four times higherthan the reported lowest ratio (0.06 [7,16] In addition, by increasing the amount of heteroatoms, we previously reported aseries of {AsO 2 (OH)} bridging Ln substituted arsenotungstates. [17] Apart from the above aspects, some efforts have been also put into explaining the influences of the usage of Ln cations in the reaction system.When the amount of Ln(NO 3 ) 3 · 6H 2 Oischanged from 0.12 gto0.17 g, 1-6 can be afforded and their yields are the highest when the amount is adjusted to about 0.15 g. In addition, dimethylamine hydrochloridei si ndispensable and plays ac onsiderably important role in improving the solubility of Ln ions and stabilizingt he structures of the target products.Ifdimethylamine hydrochloride is absent, the reactions ystem will gradually become turbid during the courseofstirring and lots of amorphous precipitation will be formed, and we cannot obtain 1-6.Onthe contrary,when dimethylamine hydrochloride is present,the reactionsystem re-mains clear during the processofstirring and 1-6 will be successfully obtained (Figure 1).…”

“…Their yields of 1 – 6 are highest when the molar ratio of Se/W is 2.00. It should be pointed out that the Dawson‐like ST [Se 2 W 14 O 52 ] 12− unit observed in 1 – 6 is relatively rare; it has been encountered during the course of preparing [(γ‐Se 2 W 14 O 52 ) 3 (Mo 2 O 2 (μ‐S) 2 (H 2 O) 2 ) 6 ] 24− , [(γ‐Se 2 W 14 O 52 ) 4 (WO 3 (H 2 O)) 8 (W 2 O 5 ) 2 (W 4 O 12 ) 2 (Mo 2 O 2 (μ‐S) 2 (H 2 O) 2 ) 4 (Mo 2 O 2 (μ‐S) 2 (SeO 3 )) 4 ] 36− , and [H 12 Pd 10 Se 10 W 52 O 206 ] 28− in acidic media when using the simple WO 4 2− /SeO 2 /SeO 3 2− precursors and different metal entities . In addition, by increasing the amount of heteroatoms, we previously reported a series of {AsO 2 (OH)} bridging Ln substituted arsenotungstates .…”

“…Their intensity data were collected with a Bruker APEX‐II CCD detector at 296(2) K with Mo Kα monochromated radiation ( λ =0.71073 Å). Direct methods were used to solve their structures and locate the heavy atoms by using the SHELXTL‐97 program package . The remaining atoms were found from successive full‐matrix least‐squares refinements on F 2 and Fourier syntheses.…”

“…Direct methods were used to solve their structures and locate the heavy atoms by using the SHELXTL-97 program package. [16] The remaining atoms were found from successive full-matrix least-squares refinements on F 2 and Fourier syntheses. Lorentz polarization and SADABS corrections were applied.…”

A Penta‐EuIII Sandwiched Dawson Selenotungstate and Its Unique Luminescence Properties

“…Because the ionization process of 1 may be accompanied by a combination of some alkali cations, protons, and even solvent water molecules, a series of broad overlapping peaks are observed. The ESI‐MS spectral results elucidate that the basic polyoxoanion skeleton structure of 1 with different cations and water molecules can still exist in aqueous solution (Table S2) . As can be seen from Figure d and Figure S4–S5, the broad peak centered at 1157.58 (calcd.…”