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The cage-like cyclobutyltellurium(IV)-containing tungstoarsenate(III) dimers [(C4H8Te-OH)2(C4H8Te)6{As2W17O61(H2O)}2]14− (1) and [{(C4H8Te)2W2O5(H2O)2As2W19O67(H2O)}2]16− (2) were synthesized in moderately acidic aqueous medium by reaction of C4H8TeI2 with the lacunary tungstoarsenates(III) [B-α-AsW9O33]9− and [As2W19O67(H2O)]14−, respectively. Polyanion 1 was isolated as a mixed cesium-guanidinium salt Cs8.5(C(NH2)3)5.5[(C4H8TeOH)2(C4H8Te)6{As2W17O61(H2O)}2]·60H2O (1a), whereas 2 crystallized as a mixed cesium-potassium salt Cs9K7[{(C4H8Te)2W2O5(H2O)2As2W19O67(H2O)}2]·90H2O (2a). Single crystal X-ray analysis demonstrated that 1a and 2a crystallized in the triclinic space group $$ P \bar{1} $$ , with a = 12.7738(8) A, b = 18.7490(14) A, c = 21.9831(14) A, α = 111.155(4)o, β = 93.312(3)o, γ = 99.530(4) and Z = 1 for 1a and a = 19.309(6) A, b = 24.674(8) A, c = 26.071(8) A, α = 63.218(17)°, β = 89.26(16)°, γ = 79.948(17)° and Z = 2 for 2a. The polyanion salts 1a and 2a were characterized by solid state NMR (1H, 13C, 125Te), FT-IR, TGA-DSC, and elemental analysis.

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The oxalato-titanium(IV)-containing, dimeric 18-tungsto-2-phosphate [Ti8(C2O4)8P2W18O76(H2O)4]18− (1) and the 32-tungsto-4-phosphate [Ti6(C2O4)4P4W32O124]20− (2) are formed upon reaction of the oxalato-titanium complex [TiO(C2O4)2]2− with the trilacunary Keggin precursor [A-α-PW9O34]9− and the hexalacunary Wells–Dawson precursor [H2P2W12O48]12−, respectively. Polyanion 1 consists of two {PW9} units encapsulating eight titanium centers and connected to each other via two Ti–O–Ti bridges, and crystallizes as a mixed potassium-sodium-lithium salt in the triclinic space group $$P{\bar{1}}$$ . Polyanion 2 comprises two {P2W16} units containing each two titanium atoms, and the two half-units are connected via two titanium atoms decorated by two oxalate groups each, and crystallizes as a mixed potassium-lithium salt in the rhombohedral space group $$R{\bar{3}}c$$ . Polyanions 1 and 2 were characterized in the solid state by single-crystal XRD, FT-IR, and TGA, whereas polyanion 2 was also investigated by 31P and 183W NMR.

We report on an improved synthesis and structural characterization of the cyclic 48-tungsto–8-arsenate(V) [H4As8W48O184]36− (1). The mixed lithium–potassium salt of this polyanion, K26.5Li9.5[H4As8W48O184]·90H2O (KLi-1), has been studied in the solid state by IR, single-crystal X-ray diffraction, and elemental analysis, and in solution by 183W NMR spectroscopy.

Reaction of (C2H5)2SnCl2 with the trilacunary 9-tungstoarsenate(V) [A–α–AsW9O34]9− in aqueous pH 5 medium resulted in the diethyltin-containing polyanion [{Sn(C2H5)2}3(H2O)6(A–α–AsVW9O34)]3− (1), which crystallized as a hydrated guanidinium salt, [C(NH2)3]3[{Sn(C2H5)2}3(H2O)4(A–α–AsVW9O34)]·9H2O (1a). Polyanion 1 represents the first example of a diethyltin-containing polyanion. The diethyltin groups are bound to the trilacunary Keggin units via two Sn–O(W) bonds involving edge-shared WO6 octahedra. Each Sn atom also has two terminal, cis-related water ligands, and two terminal, trans-related ethyl groups. Multinuclear (1H, 13C, 119Sn, 183W) NMR spectrometry indicated that polyanion 1 is stable in solution. Compound 1a was structurally characterized in the solid state by single-crystal XRD, FT-IR, as well as thermogravimetric and elemental analyses. Single-crystal X-ray analysis showed that 1a crystallizes in the orthorhombic system, space group P nma , with a = 23.5280(10) A, b = 15.5435(6) A, c = 18.6191(9) A, V = 6809.1(5) A3 and Z = 4. The structure of 1a is an extended 2D assembly of individual polyanion units 1 linked via Sn–O(W) bridges.

The 20-tungsto-4-tellurate(IV) polyanion [H2Te4W20O80]22− (1) has been synthesized and isolated in the form of its hydrated sodium salt Na22[H2Te4W20O80]·64H2O (Na-1). Na-1 has been characterized in the solid state by FTIR and TGA. Single-crystal X-ray diffraction analysis revealed that Na-1 crystallizes in the triclinic space group P $${\bar 1}$$ , with a = 12.741(2) A, b = 16.842(3) A, c = 17.197(4) A, α = 93.961(10)°, β = 107.466(8)°, γ = 108.548(8)°, V = 3281.5(11) A3 and Z = 1. The polyanion 1 comprises two [HTe2W10O40]11− fragments, connected through Te−O–W μ2-oxo bridges, and each containing a pair of face-shared WO6 octahedra. Furthermore, the 15-tungstotellurate(IV) polyanion [NaTeW15O54]13− (2) was synthesized and crystallized as a sodium salt in the orthorhombic space group Pccn, with a = 11.8841(5) A, b = 20.8934(11) A, c = 31.801(2) A, V = 7896.3(7) A3 and Z = 4.

The mixed-valence 24-vanadophosphate \( {\left[ {{\left\{ {{\text{Ru}}^{{{\text{II}}}}_{3} (dmso)_{9} {\text{PV}}^{{\text{V}}}_{{11}} {\text{V}}^{{{\text{IV}}}} {\text{Ru}}^{{{\text{III}}}} {\text{O}}_{{37}} {\text{(OH)}}_{3} } \right\}}_{2} } \right]}^{{8 - }} \) (1) has been synthesized and characterized in the solid state by IR, magnetism, EPR, XPS, and elemental analysis. Single-crystal X-ray analysis was carried out on \( {\text{Na}}_{8} {\left[ {{\left\{ {{\text{Ru}}^{{{\text{II}}}}_{3} (dmso)_{9} {\text{PV}}^{{\text{V}}}_{{11}} {\text{V}}^{{{\text{IV}}}} {\text{Ru}}^{{{\text{III}}}} {\text{O}}_{{37}} {\text{(OH)}}_{3} } \right\}}_{2} } \right]} \cdot 46{\text{H}}_{2} {\text{O}} \) (Na-1), which crystallizes in the triclinic system, space group \( \hbox{P}\overline{1} \), with a = 17.168(3) A, b = 18.1971(14) A, c = 20.1422(13) A, α = 114.753(3)°, β = 99.390(4)°, γ = 95.124(4)°, and Z = 2. Polyanion 1 has an unusual, open structure composed of 2 RuIIIO6 octahedra, 2 VIVO6 octahedra, 14 VVO5 square-pyramids, 8 VVO4 tetrahedra, and 2 PO4 tetrahedra which are all directly linked via edges and corners. The outer surface of 1 is decorated with six RuII(dmso)3 groups. XPS studies on Na-1 confirm the presence of 2 RuIII and 6 RuII as well as 22 VV and 2 VIV centers. Magnetic susceptibility data on Na-1 show that the VIV–RuIII pairs are coupled antiferromagnetically, with J1 = −13 K and J2 ∼ −3 K. We did not detect any peak in our EPR measurements on Na-1, thus supporting the conclusion that Na-1 is diamagnetic in its ground state.

We present the first examples of materials based on the Strandberg type polyanion [(O2CCH2PO3)2Mo5O15]6−, linked by Cu2+ centers via coordination to the carboxylate functions of the polyanion. Simple one-pot reaction of Rb4KNa[(O2CCH2PO3)2Mo5O15]·H2O with CuCl2·2H2O in aqueous acidic media followed by crystallization resulted in the three hybrid organic–inorganic materials {K2.6Rb1.4[(PO3CH2CO2)2Mo5O15Cu(H2O)3]·7H2O} n (KRb-1), {Na2Cs3[(PO3CH2CO2)2Mo5O15(Cu(H2O)2Cl)]·6H2O} n (NaCs-2) and {Na2.75Rb1.25[(PO3CH2CO2)2Mo5O15Cu(H2O)3]·9H2O} n (NaRb-3), which were characterized by single-crystal X-ray diffraction, IR, TGA and elemental analysis. All three compounds are 1:1 polymers of the polyanion and the Cu2+ centers are all five-coordinate with two carboxylate oxygens in a trans fashion. However, the chains in KRb-1, NaCs-2 and NaRb-3 are packed differently along b leading to different solid state structures, indicating an important role of the alkali counter cations.

The trimeric, cyclic dimethyltin-containing tungstophophate [{(Sn(CH3)2)(Sn(CH3)2O)(A-PW9O34)}3]21− (1) has been synthesized in aqueous acidic medium and characterized by IR, elemental analysis, electrochemistry, and FT-ICR MS. Single-crystal X-ray analysis was carried out on Cs12Na9[{(Sn(CH3)2)(Sn(CH3)2O)(A-PW9O34)}3]·20H2O (1a), which crystallizes in the trigonal system, space group R3, with a = b = 29.7445(7) A, c = 15.5915(7) A and Z = 3. Polyanion 1 is composed of three trilacunary (A-PW9O34) Keggin fragments that are linked on one side via three isolated dimethyltin groups and on the other side by a (Sn3(CH3)6O3) unit and three cesium ions, resulting in a cyclic assembly with C 3v symmetry. The discrete molecular, hybrid organic–inorganic 1 was synthesized by reaction of (CH3)2SnCl2 with Na9[A-PW9O34] in 0.5 M sodium acetate buffer (pH 4.8). Comparison of several characteristics of the cyclic voltammograms of 1 and (A-PW9O34)9−, including the potential location of their reduction peaks, the difference in their current intensities and their qualitative relative electron transfer speeds, supports the conclusion that the solid-state structure of 1 is retained in solution. The presence of (PW9O34)-based species in solutions of 1 was also confirmed by FT-ICR mass spectrometry.

The lanthanum-substituted polyoxometalate [{La(CH3COO)(H2O)2(α2-P2W17O61)}2]16− (1) and the neodymium-substituted species [{Nd(H2O)3(α 2 -P2W17O61)}2]14− (2) have been synthesized and characterized by IR spectroscopy and elemental analysis. Single-crystal X-ray analysis was carried out on K16[{La(CH3COO)(H2O)2(α 2 -P2W17O61)}2]⋅36H2O, which crystallizes in the triclinic system, space group P¯1, with a=12.3863(6) A, b=12.8934(6) A, c=31.7285(14) A, α=84.2000(10)°, β=81.2300(10)°, γ=61.6500(10)°, and Z=1; K6.5Nd2.5[{Nd(H2O)3(α2-P2W17O61)}2]⋅55H2O, which crystallizes in the monoclinic system, space group P21/n, with a=17.5030(9) A, b=23.7842(12) A, c=19.1869(10) A, β=100.6610(10)°, and Z=1. The head-on, trans-oid dimer 1 consists of two (α 2 -P2W17O61)10− fragments connected by a lanthanum-acetate dimer, (La2(CH3COO)2(H2O)4)4+. Each La3+ ion is nine-coordinated in a monocapped, square-antiprismatic fashion. The neodymium-derivative 2 is also a trans-oid dimer, but the mode of binding is different from 1 and is best described as side-on. Each Nd3+ ion is eight-coordinated in a square-antiprismatic fashion with three terminal water molecules.