New Perspectives in Polyoxometalate Chemistry by isolation of compounds containing very large moieties as transferable building blocks: (NMe4)5[As2Mo8V4AsO40] � 3H2O, (NH4)21[H3Mo57V6(NO)6O183(H2O)18] � 65 H2O, (NH2Me2)18(NH4)6[Mo57V6(NO)6O183(H2O)18] � 14 H2O, and (NH4)12[Mo36(NO)4O108(H2O)16] � 33 H2O

Organic/Inorganic Species Synergistically Supported Unprecedented Vanadomolybdates

Vanadomolybdates (VMos), comprised of Mo and V in high valences with O bridges, are one of the most important types of polyoxometalates (POMs), which have high activity due to their strong capabilities of gaining/losing electrons. Compared with other POMs, the preparation of VMos is difficult due to their relatively low structural stability, especially those with unclassical architectures. To overcome this shortcoming, in this study, triol ligands were applied to synthesize VMos through a beaker reaction in the presence of V₂O₅, Na₂MoO₄, and organic species in the aqueous solution. The single-crystal X-ray diffraction results indicate that two VMo clusters, Na₄{V₅Mo₂O₁₉[CH₃C(CH₂O)₃]}∙13H₂O and Na₄{V₅Mo₂O₁₉[CH₃CH₂C(CH₂O)₃]}∙13H₂O, with a similar architecture, were synthesized, which were both stabilized by triol ligand and {MoO₆} polyhedron. Both clusters are composed of five V ions and one Mo ion in a classical Lindqvist arrangement with an additional Mo ion, showing an unprecedented hepta-nuclear VMo structure. The counter Na⁺ cations assemble into one-dimensional channels, which facilitates the transport of protons and was further confirmed by proton conductivity experiments. The present results provide a new strategy to prepare and stabilize VMos, which is applicable for developing other compounds, especially those with untraditional architectures.

Synthesis, structural characterisation, and cytotoxicity studies of Bi, W, and Mo containing homo- and hetero-bimetallic polyoxometalates

Three new and different homo- and hetero-bimetallic polyoxometalate (POM) species have been synthesised by simple one-pot synthetic methods utilising naturally occurring bismite (Bi₂O₃) (or Bi(NO₃)₃·5H₂O) and aryl sulfonic acids. The POM species isolated are (NH₄)₁₄[Bi₂W₂₂O₇₆]·14H₂O (1·14H₂O), (NH₄)[Bi(DMSO)₇][Mo₈O₂₆]·H₂O (2·H₂O) and [(NH₄)₄(Mo₃₆O₁₀₈(OH)₄·16H₂O)]·45H₂O (3·45H₂O). The compounds have been characterised by X-ray crystallography, energy dispersive X-ray spectroscopy (EDX), powdered X-ray diffraction (PXRD), mass spectrometry (ESI-MS), Raman spectroscopy, thermogravimetric (TGA) and ICP analyis. In vitro cytoxicity and proliferation studies conducted on 1 and 3, highlight the low toxicity of these species.

Coordinative interaction between nitrogen oxides and iron–molybdenum POM Mo72Fe30

The process of adsorption of nitrogen monoxide and dioxide by the giant Keplerate nanocluster Mo₇₂Fe₃₀ was studied in detail under ambient conditions and air/argon atmosphere.

Bis[tris-(ethyl-enediamine-κN,N')cobalt(III)] octa-kis-μ-(3)-oxido-hexa-deca-μ(2)-oxido-tetra-deca-oxido-μ(12)-tetra-oxo-silicato-octa-molybdenum(VI)hexa-vanadium(IV,V) hexa-hydrate

The title compound, [Co(C₂H₈N₂)₃]₂[SiMo₈V₄O₄₀(VO)₂]·6H₂O, was prepared under hydro­thermal conditions. The asymmetric unit consists of a transition metal complex [Co(en)₃]³⁺ cation (en is ethyl­enediamine), one half of an [SiMo₈V₄O₄₀(VO)₂]⁶⁻ heteropolyanion, two solvent water mol­ecules in general positions and two half-mol­ecules of water located on a mirror plane. In the complex cation, the Co³⁺ ion is in a distorted octa­hedral coordination environment formed by six N atoms of the three chelating en ligands. One of the en ligands exhibits disorder of its aliphatic chain over two sets of sites of equal occupancy. The [SiMo₈V₄O₄₀(VO)₂]⁶⁻ heteropolyanion is a four-electron reduced bivanadyl-capped α-Keggin-type molybdenum–vanadium–oxide cluster. In the crystal, it is located on a mirror plane, which results in disorder of the central tetra­hedral SiO₄ group: the O atoms of this group occupy two sets of sites related by a mirror plane. Furthermore, all of the eight μ₂-oxide groups are also disordered over two sets of sites with equal occupancy. There are extensive inter­molecular N—H⋯O hydrogen bonds between the complex cations and inorganic polyoxidoanions, leading to a three-dimensional supra­molecular network.

A remarkable member of the polyoxometalates: the eight-nickel-capped alpha-keggin polyoxoazonickelate

The eight-nickel-capped polyoxoazonickelate, [Ni(20)(OH)(24)(MMT)(12)(SO(4))](NO(3))(2).6H(2)O (1; MMT = 2-mercapto-5-methyl-1,3,4-thiadiazole), has been synthesized, which has an alpha-Keggin structure with eight nickel caps. In this structure, the polyatom is the late transition metal Ni(II); the central heteroatom is S, and the organic terminal ligand becomes the primary part of the Keggin structure. This is a Keplerate-type cluster, which shows a central Ni(II)(12) cuboctahedron formed by the 12 Ni(II) centers of the classical alpha-Keggin core and a Ni(II)(8) hexahedron formed by the eight nickel caps.

A novel organotin-substituted polyoxomolybdate cluster

A novel organotin-substituted polyoxomolybdate cluster (H(3)O)(16)[(H(2)O)(2)Mo(V)O(OH)](2){Mo(VI)(28)Mo(II)(4)(NO)(4)(BuSnO)(2)[BuSn(OH)(2)](2)O(102)(H(2)O)(12)}.18H(2)O was synthesized in a 'one-pot' reaction by adopting the reduction-oxidation-reconstitution self-assembly process, which shows a {Mo(34)(NO)(4)Sn(4)} mixed metal skeleton, which is constructed from two {Mo(16)(NO)(2)Sn(2)} subunits being linked by two MoO(6) octahedra.

Syntheses and Structures of Organic−Inorganic Hybrid Compounds Based on Metal−Fluconazole Coordination Polymers and the β-Mo8O26 Anion

Five organic-inorganic hybrid compounds, namely, [Co2(fcz)4(H2O)4][beta-Mo8O26].5H2O (1), [Ni2(fcz)4(H2O)4][beta-Mo8O26].5H2O (2), [Zn2(fcz)4(beta-Mo8O26)].4H2O (3), [Cu2(fcz)4(beta-Mo8O26)].4H2O (4), and [Ag4(fcz)4(beta-Mo8O26)] (5), where fcz is fluconazole [2-(2,4-difluorophenyl)-1,3-di(1H-1,2,4-triazol-1-yl)propan-2-ol], were synthesized under hydrothermal conditions, and crystal structures of 1-5 have been determined by X-ray diffraction. In compounds 1 and 2, metal cations are linked by fluconazole ligands to form hinged chain structures and [beta-Mo8O26]4- anions act as counterions. In compound 3, Zn(II) cations are bridged by fluconazole ligands to form 2D (4,4) networks, and each pair of these networks is linked by [beta-Mo8O26]4- anions to form a sandwich double-layer structure. In compound 4, Cu(II) cations are bridged by fluconazole ligands to form 2D (4,4) networks, and these networks are connected by [beta-Mo8O26]4- anions to form a 3D framework. In compound 5, AgI cations and [Ag2]2+ units are bridged by fluconazole ligands to form 2D Ag-fcz layers, and these layers are further connected by [beta-Mo8O26]4- anions to form a complicated 3D structure with the topology of (7(2).8(1))2(7(3).8(3))(7(2).8(11).10(1).12(1))2. Thermogravimetric analyses for these compounds are also discussed in detail. The complexes exhibit antitumor activity in vitro, as shown by MTT experiments.