Discovery and isolation of the trans-isomers of two 1 : 2-type lanthanide-containing monolacunary Dawson-type tungstophosphates: [Ln^III(α₂-P₂W₁₇O₆₁)₂]¹⁷⁻ (Ln = La, Ce)

Abstract

Two novel trans-isomers of 1 : 2-type lanthanide-containing monolacunary Dawson-type tungstophosphates [Ln(α-PWO)] (Ln = La (1), Ce (2)) were successfully isolated and characterized by elemental analysis, IR, TG, and P NMR studies. Both polyanions 1 and 2 consist of one Ln ion sanwiched between two monolacunary Dawson-type tungstophosphates fragments [α-PWO] oriented at 180° with respect to each other. The solid-state and solution P NMR spectroscopy revealed that the trans-[Ce(α-PWO)] species probably quickly isomerizes to the cis-isomer species in solution.

CeIII-Functionalized Polyoxotungstates: Discrete vs Extended Architectures

“…Since then considerable work was done to identify 1:2 derivatives based on other Ln III ions − as well as to prepare the {α 1 -P 2 W 17 }-based analogues ,, and investigate spectroscopic and electrochromic properties of such polyanions. It was recently shown that [Ln III (α 2 -P 2 W 17 O 61 ) 2 ] 17– polyanions can also exist in a trans configuration that varies from the cis in the mutual orientation of the two {α 2 -P 2 W 17 } ligands . The chirality of the [ cis -Ln III (α 2 -P 2 W 17 O 61 ) 2 ] 16– structures arising from the 45° rotation of the {α 2 -P 2 W 17 } units relative to each other around the antiprismatically coordinated Ln centers was also investigated, and it was found that enantiomerically pure polyanions can be isolated by cocrystallization with d - or l -proline. , …”

A Nonclassical Polyoxoanion [P3W6(O2)6(OH)2O22]7– Constructed by Two {PW3(O2)3(OH)O9} Subunits and a {PO4} Group

“…To study the pH‐dependent stability of 1 in solution, pH‐varied 31 P NMR spectra was also measured in solution with different pH values (Figure c and 6d). When the pH values are adjusted in the alkaline environment (pH = 6.42–8.58) by adding 1 mol/L NaOH, the 1.18 ppm resonance is highly sensitive to the pH environment, and gradually shifts upfield, while –20.95 and 5.66 ppm do not show any significant change in their peak position . When the pH values are adjusted in the acid pH environment (pH = 6.42–4.46) by 1 mol/L HCl, the intensity of –20.95 and 5.66 ppm gradually decays along with the lower degree of acid, while –20.95 resonance remains basically unchanged.…”

Controllable Synthesis and Catalytic Performance of Nanocrystals of Rare-Earth-Polyoxometalates

“…However, it is very difficult to isolate RE-POMs catalysts in the nanocrystal form utilizing the reaction of RE and lacunary polyoxotungstates (POTs), which is the main synthetic strategy to prepare RE-POMs currently. − Owing to the high alkalinity of lacunary POTs and the high oxophilicity of RE ions, the reactions between them and the crystallization course of the producing RE-POMs are difficult to control. In most cases, therefore, these RE-POMs can only be isolated as single crystals in low yields.…”

“…In this work, in considering its moderate reactivity (discussed in “Synthesis and Reactivity”), Ta/W mixed-addendum POM [P 2 W 15 Ta 3 O 62 ] − was selected to react with various RE salts (Y and the full range of lanthanide except for the radioactive Pm ) to construct nanostructured novel RE-POMs. Consequently, a convenient and controllable approach was developed to generate 15 RE-POMs (listed Table ).…”