Highly Active and Dispersed Pd Nanoparticles Stabilized by Lacunary Phosphomolybdate: Synthesis, Characterization, and Liquid Phase Hydrogenation of Levulinic Acid to γ-Valerolactone

In the current scenario, one of the crucial reaction conversions is the synthesis of renewable biofuels and value-added chemicals from the hydrogenation of biomass. Therefore, in the present work, we are proposing aqueous phase conversion of levulinic acid to γ-valerolactone via hydrogenation using formic acid as a sustainable green hydrogen source over a sustainable heterogeneous catalyst. The catalyst based on Pd nanoparticles stabilized by lacunary phosphomolybdate (PMo₁₁Pd) was designed for the same and characterized by EDX, FT-IR, ³¹P NMR, powder XRD, XPS, TEM, HRTEM, and HAADF-STEM analyses. A detailed optimization study was done to achieve maximum conversion (95% conversion), using a very small amount of Pd (1.879 × 10^-3 mmol) with notable TON (2585) at 200 °C in 6 h. The regenerated catalyst was found to be workable (reusable) up to three cycles without any change in activity. Also, a plausible reaction mechanism was proposed. The catalyst exhibits superior activity against reported catalysts.

Easy Ligand Activation in the Coordination Sphere of Ru inside the [PW11O39]7- Backbone

Irradiation of the Keggin-type [PW₁₁O₃₉{Ru(NO)}]⁴⁻ (Ru-NO) polyoxometalate in CH₃CN results in rapid NO ligand elimination with the formation of [PW₁₁O₃₉{Ru^III(CH₃CN)}]⁴⁻ (Ru-CH₃CN). This complex offers an easy entry into the Ru-based chemistry of the {PW₁₁Ru} complex. Attempts to substitute N₃⁻ for CH₃CN in the presence of an NaN₃ excess lead a variety of products: (i) [PW₁₁O₃₉{Ru^III(N₃)}]⁴⁻ (Ru-N₃); (ii) [PW₁₁O₃₉{Ru^III(N₄HC-CH₃)}]⁴⁻ (Ru-Tz) as a click-reaction product; and (iii) [PW₁₁O₃₉{Ru^II(N₂)}]⁵⁻ (Ru-N₂). UV-VIS, CV, and HR-ESI-MS techniques were used for the reaction monitoring and characterization of the products.

Reactions of [Ru(NO)Cl5]2- with pseudotrilacunary {XW9O33}9- (X = AsIII, SbIII) anions

Reactions of [Ru(NO)Cl₅]^2- with pseudotrivacant B-α-[XW₉O₃₃]^9- (X = As^III, Sb^III) at 160 °C result in the rearrangement of polyoxometalate backbones into {XM₁₈} structures. In the case of arsenic, oxidation of As^III to As^V takes place with the formation of a mixture of plenary and monosubstituted Dawson [As₂W₁₈O₆₂]^6- and [As₂W₁₇Ru(NO)O₆₁]^7- anions, of which the latter was isolated as Me₂NH₂⁺ (DMA-1a and DMA-1b) and Bu₄N⁺ (Bu₄N-1) salts and fully characterized. Both α₁ and α₂ isomers of [As₂W₁₇Ru(NO)O₆₁]^7- were present in the reaction mixture; pure [α₂-As₂W₁₇Ru(NO)O₆₁]^7- was isolated as the Bu₄N⁺ salt. In the case of antimony, [SbW₉O₃₃]^9- is converted into a mixture of [SbW₁₈O₆₀]^9- and [SbW₁₇{Ru(NO)}O₅₉]^10-. The formation of trisubstituted [SbW₁₅{Ru(NO)}₃O₅₇]^12- as a minor byproduct was detected by HPLC-ICP-AES. The monosubstituted [SbW₁₇{Ru(NO)}O₅₉]^10- anion was isolated as DMAH⁺ (DMA-2) and mixed inorganic cation (CsKNa-2) salts and characterized by XRD, HPLC-ICP-AES, EA and TGA techniques. X-ray analysis shows the presence of the {Ru(NO)}-group in the 6-membered ("equatorial") belt of the Sb-free hemisphere. The experimental findings were confirmed and interpreted by means of quantum chemical calculations.

A high-nuclearity isopolyoxotungstate based manganese cluster: one-pot synthesis and step-by-step assembly

A manganese(iii,iv)-tungsten(vi) supercluster based on 72 manganese ions (48 MnIV and 24 MnIII) and 48 tungsten(vi) centers [{MnIV24MnIII12O28(H2O)23}2(W24O120)2]40- has been prepared from the carboxylic Mn12 cluster. Its structure comprises two unprecedented cage-like Mn36W24 cores linked via two Mn-O-W bonds, leading to a Mn72W48 assembly. The inorganic synthetic mechanism was investigated through different synthesis methods and comprehensive ESI-MS tests.

An unprecedented nanocage-like and heterometallic [MoO4]-polyoxomolybdate hybrid

The solvothermal oxidation of [Mo₃O₂(O₂CCH₃)₆(H₂O)₃]·ZnCl₄ has been established as a general route toward [Mo⁴⁺₃O₄]-incorporated polyoxomolybdates (Mo^IV-POMs). Two unprecedented family members: the first Mo⁴⁺-Mo⁵⁺-Mo⁶⁺ nanocage cluster, Na[MoMoMoO₄₃(OH)Py₁₂]·11H₂O (1) and the first heterometallic hybrid, [MoMoZn(PO₄)₄(OH)₂O₃₁py₃]·2(C₅H₆N)·3(C₅H₅N)·2H₂O (2) have been prepared and characterized by X-ray crystallography, elemental and DFT theoretical analyses, XPS, mass spectroscopy, cyclic voltammetry, and IR spectroscopy.

Polyoxoanions assembled by the condensation of vanadate, tungstate and selenite: solution studies and crystal structures of the mixed metal derivatives (NMe4)2Na2[WVI4VV2O19]·8H2O and (NMe4)4.83[(SeIV WVI4.57VV4.43O33)2(WVI(O)(H2O))(VVO)2.6]·10.57H2O

The reaction of SeO₃²⁻/WO₄²⁻/VO₄³⁻ gives a complex mixture of Lindqvist W–V anions and larger Se–W–V containing POMs.

Redox chemistry of ruthenium ions in mono-substituted Keggin tungstophosphate: a new synthetic extension for ruthenium derivatives based on [PW11O39RuVIN]4−

A facile approach to ruthenium-substituted Keggin-type heteropolyoxotungstates with high yield by easily controllable redox reaction is described.

An IrIV-containing polyoxometalate

In situ formation of Ir(iv) oxo-hydroxo complexes, coupled with a gradual release of tungstate ions, results in the redox-active Anderson–Evans-type polyanion [Ir^IVW₆O₂₄]⁸⁻.