Tin(ii)-functionalization of the archetypal {P8W48} polyoxotungstate

Space-Confined Nucleation of Semimetal-Oxo Clusters within a [H7P8W48O184]33- Macrocycle: Synthesis, Structure, and Enhanced Proton Conductivity

Spatially confined assembly of semimetallic oxyanions (AsO₃^3- and SbO₃^3-) within a [H₇P₈W₄₈O₁₈₄]^33- (P₈W₄₈) macrocycle has afforded three nanoscale polyanions, [{As^III₅O₄(OH)₃}₂(P₈W₄₈O₁₈₄)]^32- (As₁₀), [(Sb^IIIOH)₄(P₈W₄₈O₁₈₄)]^32- (Sb₄), and [(Sb^IIIOH)₈(P₈W₄₈O₁₈₄)]^24- (Sb₈), which were crystallized as the hydrated mixed-cation salts (Me₂NH₂)₁₃K₇Na₂Li₁₀[{As^III₅O₄(OH)₃}₂(P₈W₄₈O₁₈₄)]·32H₂O (DMA-KNaLi-As₁₀), K₂₀Li₁₂[(Sb^IIIOH)₄(P₈W₄₈O₁₈₄)]·52H₂O (KLi-Sb₄), and (Me₂NH₂)₈K₆Na₅Li₅[(Sb^IIIOH)₈(P₈W₄₈O₁₈₄)]·65H₂O (DMA-KNaLi-Sb₈), respectively. A multitude of solid- and solution-state physicochemical techniques were employed to systematically characterize the structure and composition of the as-made compounds. The polyanion of As₁₀ represents the first example of a semimetal-oxo cluster-substituted P₈W₄₈ and accommodates the largest As^III-oxo cluster in polyoxometalates (POMs) reported to date. The number of incorporated SbO₃^3- groups in Sb₄ and Sb₈ could be customized by a simple variation of Sb^III-containing precursors. Encapsulation of semimetallic oxyanions inside P₈W₄₈ sets out a valid strategy not only for the development of host-guest assemblies in POM chemistry but also for their function expansion in emerging applications such as proton-conducting materials, for which DMA-KNaLi-As₁₀ showcases an outstanding conductivity of 1.2 × 10^-2 S cm^-1 at 85 °C and 70% RH.

Coordination of Pt(IV) by {P8W48} Macrocyclic Inorganic Cavitand: Structural, Solution, and Electrochemical Studies

Hydrothermal reaction of a macrocyclic inorganic POM cavitand Li₁₇(NH₄)₂₁H₂[P₈W₄₈O₁₈₄] with [Pt(H₂O)₂(OH)₄] results in coordination of up to six {Pt(H₂O)_x(OH)_4-x} fragments to the internal surface of the polyoxoanion. The product was isolated as K₂₂(NH₄)₉H₃[{Pt(OH)₃(H₂O)}₆P₈W₄₈O₁₈₄]·79H₂O (1) and characterized by multiple techniques in the solid state (SCXRD, XRPD, XPS, FTIR, and TGA) and in solution (NMR, ESI-MS, and HPLC-ICP-AES). Electrochemical properties were studied both in solution and as components of the paste electrode. The complex shows electrocatalytic activity in water oxidation.

Unique Two-Dimensional Indium Telluride Templated by a Rare Wheel-Shaped Heterobimetallic Mn/In Cluster

A new indium telluride, [Mn_4.78In_2.22(ea)₁₂]_n[In_9.79Mn_0.21Te₁₇]_n (where Hea = ethanolamine), containing unprecedented nonsupertetrahedral [In_9.79Mn_0.21Te₂₁] units is the first example of a two-dimensional indium telluride framework templated by a rare high-nuclearity wheel-shaped heterometallic [Mn_4.78In_2.22(ea)₁₂]^4.22+ cluster. The photocurrent response and magnetic properties were investigated.

Niobium uptake by a [P8W48O184]40−macrocyclic polyanion

Incorporation of Nb into the [P₈W₄₈O₁₈₄]⁴⁰⁻anionic macrocyclic cavitand leads to formation of new Nb–W POMs. Inclusion of up to five {NbO(H₂O)}³⁺groups was observed. Solution speciation of the Nb-encapsulating macrocycles was studied by HPLC-ICP-AES and SAXS.

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}.

The homometallic polyoxotungstate archetype {P4W24}

Integration of phenylphosphonate and phenylarsonate groups render the {P₂W₁₂}-based polyoxotungstate {P₄W₂₄} accessible, yet still sufficiently reactive for consecutive functionalization steps.

Organoarsonate Functionalization of Heteropolyoxotungstates

Functionalization of the {P₈W₄₈} polyoxotungstate (POT) archetype with aromatic organoarsonates results in the first homometallic {P₈W₄₈} derivatives, with the general formula [(RAs^VO)₄P^V₈W^VI₄₈O₁₈₄]³²⁻ [R = C₆H₅ (1) or p-(H₂N)C₆H₄ (2)]. Short As−O bonds here induce unusual bending of the otherwise rigid {P₈W₄₈} macrocycle, breaking its D_4h symmetry. The obtained species also represent the first lacunary POTs functionalized with organoarsonates and can potentially act as polyoxometalate precursors themselves. We elaborate solution stability in different aqueous media using ¹H and ³¹P NMR spectroscopy and possible pathways for subsequent transformations in aqueous solutions of the functionalized polyanions. Recrystallization of the K⁺/Li⁺/dimethylammonium salt of 2 from 4 M LiCl solution yielded a further functionalized POT, [(H₃NC₆H₄AsO)₃P₈W₄₈O₁₈₄H_x{WO₂(H₂O)₂}_0.4]^{(30.2−x)−} (3), revealing dissociation of the organoarsonate fragments in slightly acidic aqueous solutions followed by their rearrangement within the inner POT cavity.

Through strong As−O−W bonds, integration of organoarsonates into heteropolyoxometalates can result in structural distortion, as demonstrated for the seminal wheel-shaped {P₈W₄₈} polyoxotungstate archetype, which binds to up to four phenyl or aminophenyl arsonate groups.

Investigation of the protonation state of the macrocyclic {HnP8W48O184} anion by modeling 183W NMR chemical shifts

¹⁸³W NMR chemical shifts of polyoxotungstates are modeled using the PACHA software: a semiempirical approach based on the partial charge formalism.

Hexanuclear tin(ii) and mixed valence tin(ii,iv) oxide clusters within polyoxometalates

A hexanuclear mixed valence tin oxide cluster [Sn₃²⁺Sn₃⁴⁺O₁₅]¹²⁻ was synthesized by selective oxidation of a tin oxide cluster within polyoxometalates.