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Research has been conducted on [(PW (sub)11 O (sub)39) (sub)2 (H (sub)4 Mo (sub)4 S (sub)4 O (sub)6)] (super)10- anions. The authors demonstrate that these anions have been produced via stereospecific addition of the oxothiocation to the monovacant anion.

The reaction of {SbW9O33}9- with {Mo2O2S2}2+ has been studied. The {SbW9O33}{Mo2O2S2} products are labile in solution and very sensitive to experimental conditions. Two new hybrids, {Mo2O2S2}-containing tungstoantimonate anions, namely [(SbW9O33)2(Mo2O2S2)3]12- and [K(SbW9O33)2(Mo2O2S2)WO(H2O)]11-, have been fully characterized in the solid state and in solution by 183W NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: Reaction of the [Mo2O2S2(OH2)6]2+ aqua cation and [WO4]2− with the trivacant ion [α-B-AsW9O33]9− in acidic condition (pH=1.4) leads to the formation of a {Mo2S2O2}-supported polyoxotungstate. The mixed salt NMe4K12[(α–AsW9O33)3(WO(OH2))3(Mo2O2S2(H2O)4)]•20H2O (noted TMAK 12 –1) has been obtained as single crystals and structurally characterized by X-ray diffraction analysis. The structural analysis of TMAK 12 -1 reveals a molecular polyoxotungsto-arsenate (III) framework consisting of three α-{AsW9O33} subunits mutually linked by three {O=W-OH2}4+ groups. The resulting triangular arrangement delimits a large “open-space”, lined on the periphery by six terminal oxygen atoms. The central cavity is partially filled by a single {Mo2O2S2(OH2)4}2+ which spans two {AsW9O33} subunits. Furthermore, three potassium ions have been located, one being embedded within the central cavity and the other two, symmetrically distributed at the periphery of the central cavity. In the solid state, two anions 1 interact through hydrogen bonds and ionic contacts to give a large dimeric arrangement bordered by two TMA+ cations. 1 has been characterized in solution (Li+ salt) by its 183W NMR spectrum which contains 16 lines in agreement with the C s idealized symmetry assumed for the isolated anion 1. Infrared data and elemental analysis are also supplied. [Copyright &y& Elsevier]

The chemical system based on the [Mo2O2S2(OH2)6]2+ aqua cation (noted L) and the trivacant [AsW9O33]9- polyoxometalate (noted POM) has been investigated. Depending upon the ionic strength and the nature of the alkali cations, these complementary components assemble to yield three different architectures derived as hexamer (1), tetramer (2), and dimer (3). This series of clusters displays the same stoichiometry {POM6L9}36-, {POM4L6}24-, and {POM2L3}12- for 1, 2, and 3, respectively, and their conditions of formation differ mainly by the nature and the concentration of the alkali cation (from Li to Cs). Structural characterizations of 1 reveal a large hexameric supramolecular scaffold (about 25 Å in diameter), which encloses a large internal hole (about 200 ų) filled by water molecules and alkali cations (Na+ or K+). The hexameric scaffold 1 exhibits a rare flexibility property evidenced in the solid state by two distinct conformations, either eclipsed (1a) or staggered-off (1b). Both conformations appear clearly separated by a large twist angle (~40°) and depend mainly on the composition of the internal hole. Structure of anion 2 shows a tetrahedral arrangement where the four POM units and the six connecting {Mo2O2S2} linkers are located at the corners and at the edges, respectively. The structure of anion 3 corresponds to the simplest arrangement, described as a dimeric association of two POM units linked by three {Mo2S2O2} pillars. Stability of the hexameric scaffold has been investigated in solution by 183W and 39K NMR and by UV-vis, showing that stability of 1 depends strongly on the proportion of potassium ions, which interfere through host-guest exchange. Density functional methodology (DFT) has been applied to compute the geometries and energies of dimer (3), tetramer (2) and hexamer (1) based on {AsW9O33} (POM) and {Mo2O2S2} (L) units. Calculations tend to show that internal cations act as "glue" to maintain the POM units connected through the conformationally inward-directed {Mo2O2S2} linkers. [ABSTRACT FROM AUTHOR]

Abstract: Reaction at pH=2.3 of the [Mo2O2S2(OH2)6]2+ aqua cation with the tetravacant ion [β-B-HAs2W8O31]7− leads to the formation of a red solid from which three mixed salts have been obtained as single crystals and characterized by X-ray diffraction analysis. Three mixed salts K-5a, RbNa-5b, DMACs-5c exhibit a similar molecular arrangement consisting in three {β-HAs2W9O34} subunits mutually linked by three {Mo2O2S2} groups. The triangular arrangement delimits a large open-cavity, lined on the periphery by three outer {As–OH} groups and closed at the bottom by a small hexagonal pocket formed by six terminal oxygen atoms. The central hexagonal cavity is filled either by a potassium, a rubidium or a cesium cation. The outer {As–OH} groups are pointed towards two directions labelled up and down, respectively. In K-6a the three {As–OH} bonds are in up configuration leading to the {up, up, up} isomer. The structure of RbNa-5b is rather consistent with the superposition of the two {up, up, up} and {down, up, up} isomers disordered over the same crystallographic site, while only the {down, up, up} isomer is present in DMACs-5c. In solution, 183W NMR characterization of 6a as sodium salt results in a complicated spectrum consistent with the simultaneous presence of the four isomers, {up, up, up}, {down, up, up}, {down, down, up} and {down, down, down}, respectively. 5a reacts with three equivalents of iodine to give CsNa-6 isolated as single crystals. In 6, four β-{AsW9O33} moieties are located at the corner of a super tetrahedron and are mutually connected by six {Mo2O2S2} linkers. The three outer {As–OH} groups can be selectively removed by iodine, this oxidation reaction consisting in fact in a deprotecting process permitting the extension of the arrangement from triangular to tetrahedral. [Copyright &y& Elsevier]

[(PW[sub 11]O[sub 39])[sub 2](Mo[sub 4]S[sub 4]O[sub 4](OH[sub 2])[sub 2])][sup 10-] anions were obtained through the stereospecific addition of the [Mo[sub 2]S[sub 2]O[sub 2]][sup 2+] oxothiocation to the monovacant α-[PW[sub 11]O[sub 39]][sup 7-] anion. K[sub 10][(PW[sub 11]O[sub 39])[sub 2]Mo[sub 4]S[sub 4]O[sub 4](OH[sub 2])[sub 2])]·25H[sub 2]O has been isolated as crystals and characterized by X-ray diffraction. The structure revealed a "sandwich-like" dimer of two α-[PW[sub 11]O[sub 39]][sup 7-] subunits assembled by the noteworthy central cluster {H[sub 4]Mo[sub 4]S[sub 4]O[sub 6]}. The crystallization of the crude product produces an isomerically pure compound, which was characterized by [sup 31]P and [sup 183]W NMR. IR data were also supplied. In solution, the compound isomerizes, giving a second diastereoisomer. A kinetic experiment, carried out by [sup 31]P NMR, allowed the conditions of the thermodynamic equilibrium to be determined. A structural relationship between the two isomers is proposed, fully consistent with NMR data. Cisoid and transoid isomers result in the relative disposition of each [PW[sub 11]O[sub 39]][sup 7-] subunit, either staggered or eclipsed. An investigation of the formation of the [Mo[sub 2]O[sub 2]S[sub 2]][sup 2+] unit from the polycondensed cyclic precursor [Mo[sub 10]S[sub 10]O[sub 10](OH)[sub 10](H[sub 2]O)[sub 5]] and the aggregation process resulting in the oxothio [(PW[sub 11]O[sub 39])[sub 2](Mo[sub 4]S[sub 4]O[sub 4](OH[sub 2])[sub 2])][sup 10-] compound has been undertaken. The studies were monitored by [sup 31]P NMR and UV-vis spectroscopies. The reaction is quantitative in nearly stoichiometric conditions. [ABSTRACT FROM AUTHOR]

The chemical system based on the [Mo(2)O(2)S(2)(OH(2))(6)](2+) aqua cation (noted L) and the trivacant [AsW(9)O(33)](9-) polyoxometalate (noted POM) has been investigated. Depending upon the ionic strength and the nature of the alkali cations, these complementary components assemble to yield three different architectures derived as hexamer (1), tetramer (2), and dimer (3). This series of clusters displays the same stoichiometry {POM(6)L(9)}(36-), {POM(4)L(6)}(24-), and {POM(2)L(3)}(12-) for 1, 2, and 3, respectively, and their conditions of formation differ mainly by the nature and the concentration of the alkali cation (from Li to Cs). Structural characterizations of 1 reveal a large hexameric supramolecular scaffold (about 25 Å in diameter), which encloses a large internal hole (about 200 Å(3)) filled by water molecules and alkali cations (Na(+) or K(+)). The hexameric scaffold 1 exhibits a rare flexibility property evidenced in the solid state by two distinct conformations, either eclipsed (1a) or staggered-off (1b). Both conformations appear clearly separated by a large twist angle (~40°) and depend mainly on the composition of the internal hole. Structure of anion 2 shows a tetrahedral arrangement where the four POM units and the six connecting {Mo(2)O(2)S(2)} linkers are located at the corners and at the edges, respectively. The structure of anion 3 corresponds to the simplest arrangement, described as a dimeric association of two POM units linked by three {Mo(2)S(2)O(2)} pillars. Stability of the hexameric scaffold has been investigated in solution by (183)W and (39)K NMR and by UV-vis, showing that stability of 1 depends strongly on the proportion of potassium ions, which interfere through host-guest exchange. Density functional methodology (DFT) has been applied to compute the geometries and energies of dimer (3), tetramer (2) and hexamer (1) based on {AsW(9)O(33)} (POM) and {Mo(2)O(2)S(2)} (L) units. Calculations tend to show that internal cations act as "glue" to maintain the POM units connected through the conformationally inward-directed {Mo(2)O(2)S(2)} linkers., (© 2011 American Chemical Society)

Coordination of the [Mo(3)S(4)(H(2)O)(9)](4+) cluster with the trivacant [AsW(9)O(33)](9-) ion gives the supramolecular complex [{(H(4)AsW(9)O(33))(4)(Mo(3)S(4){H(2)O}(5))}(2)](12-) (1) in good yield. The structure of 1 shows that two [H(4)AsW(9)O(33)](5-) subunits sandwich a single central [Mo(3)S(4)(H(2)O)(5)](4+) ion to give a basic monomeric unit [(H(4)AsW(9)O(33))(2){Mo(3)S(4)(H(2)O)(5)}](6-). In the solid state, a supramolecular dimeric association is evidenced that consists of two [(H(4)AsW(9)O(33))(2){Mo(3)S(4)(H(2)O)(5)}](6-) units held together by twelve hydrogen bonds and four SS contacts. Complex 1 reacts with NaAsO(2), AgNO(3) and CuI to give compounds 2, 3 and 4, respectively. X-ray structural analysis reveals that the molecular arrangements of 2 to 4 are closely related to the parent structure of 1. {AsOH}(2+), Ag(+) and Cu(+) ions are located on three distinct pairs of sites. Two hanging {AsOH}(2+) groups in 2 are symmetrically attached to two opposite {AsW(9)O(33)} subunits. Complex 3 is the first example of an Ag/{Mo(3)S(4)} combination in which the environment of the two equivalent Ag(+) cations is remarkable for containing two sulfur atoms belonging to {Mo(3)S(4)}, two oxygen and one central arsenic atom of the {AsW(9)O(33)} subunits. Potentiometric titration shows that the addition of Ag(+) ions is quantitative and occurs in two successive steps (K(1)=4.1 x 10(6) and K(2)=2.3 x 10(5) L mol(-1)), which is consistent with the retention of the supramolecular cluster in solution. The structure of 4 reveals a single copper atom embedded in the central part of the dimer. The Cu(+) cation is bound to four sulfur atoms to complete a cuboidal moiety. UV/Vis studies in solution indicate that the stability of the dimeric assemblies of 2, 3 and 4 is significantly enhanced by the presence of Cu(+) or Ag(+) ions, which act as additional coordination linkers within the supramolecular cluster. The anions 1 to 4 were characterised by (183)W NMR spectroscopy in solution. The 10-line spectra recorded for each of them are consistent with an averaged C(2h) molecular symmetry in solution.