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

Syntheses, Crystal Structure, Electrocatalytic, and Magnetic Properties of the Monolanthanide-Containing Germanotungstates [Ln(H2O) n GeW11O39]5- (Ln = Dy, Er, n = 4,3)

Two monolanthanide-containing polyanions based on monolacunary Keggin germanotungstates [Ln(H2O) n GeW11O39]5- (Ln = Dy, Er, n = 4,3) have been synthesized in simple one-pot synthetic procedure and compositionally characterized in solid state by single-crystal X-ray diffraction, powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and elemental analysis. Electronic absorption and emission spectra of the title compounds in solution were also studied. The [DyIII(H2O)4GeW11O39]5- Keggin POM exhibits a slow relaxation of magnetization. The cyclic voltammetry measurements and mass spectrometry were carried out to check the stability of the compounds in solution. Both polyanions prove efficient in the electrocatalytic reduction of nitrite. To our knowledge, this observation establishes the first example of electrocatalysis of nitrite reduction by all inorganic monolanthanide-containing germanotungstates family.

Synthesis, structure and electrochemical characterization of an isopolytungstate (W4O16) held by MnII anchors within a superlacunary crown heteropolyanion {P8W48}

The first example of an isopolyanion (W₄O₁₆) held by redox-active Mn^II anchors within an archetypal superlacunary heteropolyanion {P₈W₄₈}.

Synthesis and characterization of carbonate-encapsulated ytterbium- and yttrium-containing polyoxotungstates

A sandwiched-type carbonate-encapsulated yttrium-containing arsenotungstate(III) has been synthesized under mild reaction conditions. The polyanion [NaCH₃COO{Y₂(H₂O)₃(B-α-AsW₉O₃₃)₂(W₂O₅)(CO₃)}]^12- (1) was isolated as a solid crystalline material by the reaction of a Y^III salt with the sodium salt of trilacunary [AsW₉O₃₃]^9- in sodium acetate solution. The sodium salt of the polyanion, i.e. Na₁₂[Na(CH₃COO){Y₂(AsW₉O₃₃)₂(W₂O₅)(CO₃)(H₃O)₃}]·22H₂O (1a), was characterized by various analytical techniques, such as FT-IR, single-crystal X-ray diffraction (SC-XRD), TGA (thermogravimetric analysis), ¹³C NMR and ESI-MS (electrospray ionization mass spectrometry). SC-XRD studies revealed that the polyanion crystallizes in the triclinic space group P-1. The structure showed that the polyanion is a carbonate-encapsulated sandwich-type species, consisting of two trilacunary B-α-[AsW₉O₃₃]^9-, with a lone-pair-containing As^III heteroatom, together with two extra tungsten centres and two yttrium cations at the sandwich position, where CH₃COO^- and Na⁺ ions act as linkers between the two polyanion units. In addition, we have also synthesized two carbonate-encapsulated germanotungstates(IV), without lone-pair-containing heteroatoms, with the formula [Ln₃(A-β-GeW₉O₃₄)₂(CO₃)(H₂O)₃]^13- [Ln = Y^III (2) and Yb^III (3)], i.e. Y₂K₃Na₄[Y₃(A-β-GeW₉O₃₄)₂(CO₃)(H₂O)₃]·19H₂O (2a) and YbK₈Na₂[Yb(A-β-GeW₉O₃₄)₂(CO₃)(H₂O)₃]·16H₂O (3a), and characterized them by FT-IR, SC-XRD, TGA and ESI-MS. Here, the lanthanide ions act as linkers, extending the structures into higher dimensions. Sodium and potassium ions also play a key role as linkers, further extending the structure. The packing shows the presence of certain hydrophilic pores within the structure.