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Polyoxometalate Molybdenum blue (MBs) complexes typically exist as discrete multianionic clusters and are composed of repeating Mo building units. MB Wheels, such as {Mo176} and {Mo154} are made fr...

The construction of pure-inorganic framework materials with well-defined design rules and building blocks is challenging. In this work, we show how a polyoxometalate cluster with an integrated pore, based on [P8 W48 O184 ]40- (abbreviated as {P8 W48 }), can be self-assembled into inorganic frameworks using silver ions, which both enable reactions on the cluster as well as link them together. The {P8 W48 } was found to be highly reactive with silver ions resulting in the in situ generation of fragments, forming {P9 W63 O235 } and {P10 W66 O251 } in compound (1) where these two clusters co-crystallize and are connected into a POMZite framework with 11 Ag+ ions as linkers located inside clusters and 10 Ag+ linking ions situated between clusters. Decreasing both the concentration of Ag+ ions, and the reaction temperature compared to the synthesis of compound (1), leads to {P8 W51 O196 } in compound 2 where the {P8 W48 } clusters are linked to form a new POMZite framework with 9 Ag+ ions per formula unit. Further tuning of the reaction conditions yields a cubic porous network compound (3) where {P8 W48 } clusters as cubic sides are joined by 4 Ag+ ions to give a cubic array and no Ag+ ions were found inside the clusters.

Since 1996 when Muller et al. determined the first giant Molybdenum Blue (MB) wheel {Mo154} and revealed the 200-year-old mystery, many hundreds of compounds of this type and analogous giant polyoxomolybdates have been discovered. These multifunctional and highly complex molecular nano-objects of reduced molybdenum oxide, reaching to the size of proteins, have potential applications in materials science, catalysis, electronic devices and even as biosensors. This family of molecules displays exquisite structures, and even opens the way for adaptive and autocatalytic chemistry. Muller and a few other groups published a number of exceptional reviews on the topic of giant polyoxomolybdates. This chapter presents a detailed summary of recent advances including new synthetic methods, characterization, supramolecular chemistry and applications, focusing on recent work on lanthanide-substituted and amino-acid/peptide functionalized MB wheels, confined reaction in the Keplerate {Mo132} ball and the new discovery of Molybdenum Reds.

Water oxidation is a key reaction for the conversion of solar energy into chemical fuels, but effective water-oxidation catalysts are often based on rare and costly precious metals such as Pt, Ir or Ru. Developing strategies based on earth-abundant metals is important to explore critical aspects of this reaction, and to see whether different and more efficient applications are possible for energy systems. Herein, we present an approach to tuning a redox-active electrocatalyst based on the doping of molybdenum into the tungsten framework of [Co4(H2O)2(PW9O34)2]10−, known as the Weakley sandwich. The Mo-doped framework was confirmed by X-ray crystallography, electrospray ionization mass spectrometry and inductively coupled plasma optical emission spectrometry studies. The doping of molybdenum into the robust Weakley sandwich framework leads to the oxidation of water at a low onset potential, and with no catalyst degradation, whereby the overpotential of the oxygen evolution reaction is lowered by 188 mV compared with the pure tungsten framework.

The hardening behavior of Al-0.25Sc and Al-0.25–0.12 (wt.%) alloys during isothermal annealing were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), optical microscopy (OM), and hardness measurements. The results show that Sc-containing aluminum alloy contained fine dispersion of spherical secondary Al3Sc particles, which developed during the annealing process. Al3(Sc, Zr) precipitates in the Al-0.25Sc-0.12Zr alloys are core-shell structure. Different isothermal annealing temperatures can lead to different strengthening effects on the alloys. Al-0.25Sc and Al-0.25Sc-0.12Zr alloys both exhibit obvious annealing hardening behavior, and the ternary Al-0.25Sc-0.12Zr alloy shows better thermal stability than Al-0.25Sc alloy.

The effect of Scandium (Sc) and Copper (Cu) on the microstructure and mechanical properties of the 3003 alloy were investigated. The results showed that the addition of Cu can promote the precipitation of α-Al(Mn,Fe)Si dispersoids during brazing. With the addition of Sc and Cu, the average grain size of 3003 alloy was significantly refined. The recrystallization resistance of the simulated brazing alloy was improved by Sc, which was mainly due to the precipitation of Al3Sc particles. The α-Al(Mn,Fe)Si dispersoids and Al3Sc particles exist simultaneously after annealing, which can improve the strength of Sc-containing 3003 alloy. The 3003 alloy added with Sc and Cu has the best mechanical performance among the three experimental alloys.

We report the synthesis, structural, and electronic characterization of the theoretically predicted, but experimentally elusive δ-isomer of the Keggin polyanion. A family of δ-Keggin polyoxoanions of the general formula, (TEA)HpNaq [H2M12(XO4)O33(TEA)].rH2O where p, q, r = [2,3,8] for 1 and [4,1,4] for 2 were isolated by the reaction of tungstate(VI) and vanadium(V) with triethanolammonium ions (TEAH), acting as a tripodal ligand grafted to the surface of the cluster leading to the entrapment and stabilization of the elusive polyanhionic δ Keggin archetype. The δ-Keggin species were characterized by single-crystal X-ray diffraction, FT-IR, UV-vis, NMR and ESI-MS spectrometry. Electronic structure and structure-stability correlations were evaluated by means of DFT calculations. The compounds exhibited multi-electron transfer and reversible photochromic properties by undergoing single-crystal-to-single-crystal (SC-SC) transformations accompanied with colour changes under light

The symmetry, structure and formation mechanism of the structurally self-complementary {Pd84} = [Pd84O42(PO4)42(CH3CO2)28](70-) wheel is explored. Not only does the symmetry give rise to a non-closest packed structure, the mechanism of the wheel formation is proposed to depend on the delicate balance between reaction conditions. We achieve the resolution of gigantic polyoxopalladate species through electrophoresis and size-exclusion chromatography, the latter has been used in conjunction with electrospray mass spectrometry to probe the formation of the ring, which was found to proceed by the stepwise aggregation of {Pd6}(-) = [Pd6O4(CH3CO2)2(PO4)3Na(6-n)H(n)](-) building blocks. Furthermore, the higher-order assembly of these clusters into hollow blackberry structures of around 50 nm has been observed using dynamic and static light scattering.

Reaction of 9-hydroxyphenalenone 1 with triflic anhydride allows access to 9-trifluoromethanesulfonyloxyphenalenone 2. The reactivity of 2 is explored in the reactions with pyridine, iodide, and azide. Structural aspects of 4, including carbonyl–iodine interactions, are investigated by X-ray crystallography. Both 2 and 9-iodophenalenone 4 are expected to be valuable precursors in the synthesis of further 9-functionalised phenalenones.

A one-pot strategy exploiting the structure directing effects of SeIV and TeIV heteroatoms has yielded the highest nuclearity noble metal containing polyoxometalates to date; including the palladium-rich selenotungstate isomers K28[H12Pd10Se10W52O206]·65H2O (1) and K26[H14Pd10Se10W52O206]·68H2O (2), and the nanoscale tellurotungstate cluster Na40[Pd6Te19W42O190]·76H2O (3). These reaction systems exhibit remarkable structural flexibility and point to a new route towards the synthesis of complex heterometallic species, in which multiple lacunary polyoxometalate ‘building blocks’ have been assembled to trap a transient oxopalladate species suspected to play a role in the assembly of several common polyoxopalladates. Mass spectrometry has been applied to explore and compare the solution stability of compounds 1–3, demonstrating the markedly different properties of the SeIV and TeIV templated systems. Electrochemical analysis of 1 has been provided and is dominated by Pd redox processes, with reduction of the cluster resulting in electrodeposition of Pd metal and observation of the subsequent formation of PdO species, concurrent with previously reported oxopalladate containing species.

Al-5.8Mg-0.4Mn-0.25Sc-0.1Zr (mass fraction, %) alloys were prepared by water chilling copper mould ingot metallurgy processing which was protected by active flux. The recrystallization temperature and nucleation mechanism of the alloy were studied by means of hardness tests, observations of optical microscopy and transmission electron microscopy. The results show that the anti-crystallization ability can be significantly improved by adding minor Sc and Zr into Al-Mg-Mn alloy. This can be proved by a much higher recrystalliztion temperature (450 °C) than Al-Mg-Mn alloy without Sc and Zr (150 °C). The main reason of the great increase of recrystallization temperature can be attributed to the strong pinning effect of highly disperseded Al3(Sc,Zr) particles on dislocations and sub-grain boundaries. The recrystallizing process reveals itself the nucleation mechanism of the alloy involving not only the sub-grain coalescence but also the sub-grain growth.

A new family of thiometalate-based composite molecular materials is synthesized and characterized. 1.6 and 1.9 nm-sized clusters are observed in the gas phase utilizing high-resolution ESI-MS. The diversity of the selenite anions as an inorganic ligand is demonstrated by the isolation of the highest nuclearity selenium-based oxothiometalate materials reported so far. The observed proton conductivity of the selenite based oxothiometalate species renders them as promising alternative materials for fuel-cell applications.

10.1002/anie.201303126 Non-mixed-valent reduced polyoxometalates, namely {W18O56XO6} Dawson-like clusters (X=IVII or TeVI) with a localized redox active template have been synthesized and redox properties compared with the pure tungsten control (that is, X=WVI). Upon one-electron reduction, the electron localizes on the main-group element, giving IVI or TeV, respectively. These clusters have potential as a new type of electron-transfer reagent.

By using solubility control to crystallize the prenucleation clusters of hydrosol, a family of titanium-oxo clusters possessing the {Ti18O27} core in which the 18 Ti(IV)-ions are uniquely connected with μ-oxo ligands into a triple-decked pentagonal prism was obtained. The cluster cores are wrapped by external sulfate and aqua ligands, showing good solubilities and stabilities in a variety of solvents including acetonitrile and water and allowing their solution chemistry being studied by means of electrospray ionization mass spectroscopy, (17)O NMR, and vibrational spectroscopy. Furthermore, this study provides new titanium oxide candidates for surface modifications and homogeneous photocatalysis.

The nanosized, 2.2 nm, {Mo40} oxo(thio)metalate wheel was isolated in high yield using a direct synthetic procedure which involves acidification of a molybdate solution in the presence of the {Mo2O2S2}2+oxothio cation as the starting material. The [(Mo8O28)4(Mo2O2S2)4]24– wheel, 1a, was characterised by single-crystal X-ray diffraction analysis, IR, Raman, UV/Vis and flame atomic absorption spectroscopy (FAAS). Solid state and solution Raman spectroscopic studies allowed the unambiguous determination of the critical conditions by which compound 1 retains its integrity in solution. Electrospray ionisation mass spectrometry (ESI-MS) studies carried out on aqueous solutions of the crystalline material showed that the nanosized wheel retains its integrity in concentrated solutions. High resolution ESI-MS studies allowed the direct observation of the discrete wheel as well as the distinct self-assembly stages of its formation; from the fundamental building units through to the final formation of well resolved aggregations of 1D chains which is in agreement with the solid state studies.

An adaptable polyoxometalate macrocycle: The crown-type polyoxometalate [P8W48O184]40− has been prepared in the absence of potassium to give two new mixed lithium/ammonium compounds, allowing cation binding within the heteropolyanion to be investigated. Characterization of binding sites in the {P8W48} cluster could enable prediction of reaction products and selective functionalization of internal and external binding sites.

Vanadate(V)-templated Dawson-type capsules {V(IV)M(VI)(17)(VO(4))(2)} (M = Mo, W; 1-2) have been synthesized and investigated by electrochemical methods in aqueous and organic media using spectroscopic techniques, EPR, UV-vis/NIR, IR, and CSI-MS (cryospray ionization mass spec.), and the clusters have been examined in the solid state by magnetic studies. The collision-induced dissociation (CID-MS) studies confirmed the solution structures as well as helped pinpoint the position of the vanadium ion on the {VM(17)}-type shell, which was corroborated by EPR and theoretical studies.

A design approach for the preparation of the {(DMAH)7[H2SbW18O60]} (DMAH-2) and {(DMAH)7[H2BiW18O60]} (DMAH-3) (DMAH = dimethylammonium) systems in a highly pure crystalline form is presented, and the latter is characterized by electrospray ionization mass spectrometry (ESI-MS) methods for the first time. These, together with the archetypal [W10O32] cluster, are used as precursors for the formation of unique framework materials incorporating Ag(I) as a linking species. The systems are fully characterized by X-ray crystallography, elemental analysis, IR and thermogravimetric analysis (TGA), and the pyrolysis of the {Ag4-W10O32} system (1) leads to the formation of silver microparticles embedded in the resulting tungsten oxide and this has been observed by us previously with other systems. In contrast, the carefully controlled decomposition of the antimony and bismuth systems {Ag418O60} (Ag-2) and {Ag4-SbW18O60} (Ag-3) gives rise to the formation of highly pure, discrete silver microparticles as confirmed b...

The exploration of the self-organization of a range of the polyoxometalate-based molecular structures reveals a diverse range of surface patterns and morphologies on solid substrates of technological interest, including methylated and hydroxylated silicon surfaces (namely, SiCH3 and SiOH). By exploiting the interplay between the intrinsic molecular properties and the surface chemistry as well as dynamic spatiotemporal phenomena (e.g., dewetting), we show that these systems can yield 0D, 2D, and 3D architectures via solution deposition at the solid surface, including nanodots, discs, lamellas, porous networks, and layer-by-layer assemblies. In general, we observed that layer-by-layer growth is a common feature on low surface energy SiCH3. In addition, the polyoxometalate derived architectures are able to effectively modulate the drop spreading dynamics on high surface energy SiOH, so that dewetting induces the formation of nanodots from dilute solutions of the precursor POM hybrid, whereas using high conce...

A novel sandwich-type silicotungstate motif, K18[MnII2{MnII(H2O)5MnIII3(H2O)(B-β-SiW9O34)(B-β-SiW6O26)}2]·20H2O 1, has been isolated from the reaction of K8[γ-SiW10O36]·12H2O and manganese ions in aqueous acidic media. The transition metal-substituted polyoxometalate (TMSP) 1 has been fully characterized by single-crystal X-ray diffraction, elemental analysis, thermogravimetric analysis, and infrared spectroscopy. This dimeric polyanion consists structurally of the sandwich polyanion {MnII(H2O)5MnIII3(H2O)(B-β-SiW9O34)(B-β-SiW6O26)}, dimerized via two manganese(II) linker ions. Each monomeric unit is composed of two non-equivalent Keggin fragments, (B-β-SiW8O31) and (B-β-SiW6O26), linked to each other via three manganese ions resulting in a truncated {Mn3O4} cubane core. Experimental, structural, and electrochemical aspects of the material are reported and discussed.

The complexation of copper(II) perchlorate with cis,trans-1,3,5-triamino-cyclohexane (transtachH) yields four related mononuclear complexes, [Cu(trans-tachH)2](ClO4)4・(H2O) (1), [Cu(transtachH) 2](ClO4)4・2MeOH (2), [Cu(trans-tachH)2(ClO4)](ClO4)3 (3) and [Cu(trans-tach)(transtachH)( ClO4)2](ClO4)・H2O (4). These complexes only differ with respect to ligand protonation, solvent coordination / content, and counterion binding, yet these small differences manifest as vast differences in the supramolecular structures, and we also show that certain crystalline phases of these four compounds persist for different lengths of time in the mother liquor.

Reaction of (NBu4)2[Mo2O7] with [Cu(CH3CN)4](PF6) in acetonitrile results in isolation of the orange β-octamolybdate [Cu(CH3CN)4]2[Mo8O26Cu2(CH3CN)4] (1) along with the colourless α-octamolybdate [Cu(CH3CN)4]4[Mo8O26]·2CH3CN (2). Both products decompose rapidly upon removal from their mother liquors, forming an insoluble, dark brown coloured phase with the composition Cu4[Mo8O26]·0.6CH3CN·16H2O (3). The copper(I) acetonitrile derivatised isopolyanion in 1 thus represents an intermediate structure between the simple, underivatised octamolybdate 2 and fully condensed, polymeric phase 3.

The cryo game: Heteroatom-embedded nanofunctional clusters are described that incorporate a [Te(VI)O(6)](6-) species contained within a {W(18)O(54)} cage. Not only does the tellurium-based species activate the {W(18)O(54)} cluster surface for assembly of larger nanoscale structures, such as [H(10)Te(VI) (2)W(58)O(198)](26-), it also undergoes a redox transformation inside the cluster from [Te(VI)O(6)](6-) to [Te(IV)O(3)](2-).

Cyclopalladated complexes with a N,N-dimethylaminomethylferrocenyl (dmaf) backbone and three pyridine co-ligands, [Pd{(η5-C5H5)Fe[(η5-C5H3)CH2NMe2]}Cl(R-Py)] (2: R = 4-H; 3: R = 4-cyano; 4: 4-N,N-dimethylamino) have been synthesized and characterized. The single crystal X-ray diffraction analyses show that the palladium(II) in both 3 or 4 is coordinated in a distorted square planar geometry with the two nitrogen atoms trans to each other. The three palladacyles were shown to greatly catalyze the methanolysis of the P S containing pesticide parathion but showed different accelerations. It was found that the replacement of phenyl by ferrocenyl in the palladacycle backbone of 2 lowers the kinetic pKa s s of the Pd-(HOCH3) required for activity by almost 2 units.

cis,trans-1,3,5-Triaminocyclohexane (trans-tach) has been shown to be an excellent ligand in the synthesis of discrete complexes, molecular clusters, and infinite architectures. Herein, we report the Schiff-base derivitization of trans-tach to form cis,trans-1,3,5-tris (pyridine-2-carboxaldimino) cyclohexane (ttop), and the complexation of this ligand with copper(II) salts. The complexation reaction leads to the crystallization of transition-metal complexes with nuclearities of 1, 2, and 4, and the formation of the complexes can be followed stepwise, in real time, using electrospray mass spectrometry.

Two cyclic cobalt-substituted heteropolyoxometalates K15Li5[Co10(H2O)34(P8W48O184)]·54H2O (1) and K8Li12[Co10(H2O)44(P8W48O184)]·60H2O (2) have been synthesised from the reaction of Co(II) ions and the superlacunary {P8W48} polyanion in mildly acidic aqueous media. The cluster's anion cavities are filled with Co(II) and K cations and careful manipulation of reaction conditions determines the formation of distinct Co-linked frameworks.

Control, but not a freak: A series of dodecanuclear coordination clusters of NiII and CoII with isostructural frameworks is prepared with unparalleled structural and compositional control. At different pH values, the respective clusters can be detected in solution by cryospray mass spectrometry. The positions of the metal centers in the mixed-metal clusters are determined from the magnetic properties.

Compounds (III) and (IV) are synthesized by reduction of an acidified suspension of cerium polymolybdate in water and characterized by single crystal XRD, IR and Raman spectroscopy, and electrospray-ionization ion-mobility mass spectrometry.

The coordination chemistry of the tetradentate pyridyl N-donor ligand cis-3,5-bis-[2-pyridinyleneamin]-trans-hydroxycyclohexane (DDOP) has been investigated with zinc(II) nitrate and triflate. The resulting complexes, [Zn(DDOP)(H2O)(NO3)](NO3) (1), and [Zn(DDOP)(H2O)(OTf)](OTf) (2) differ not only in their counterions, but also the arrangement of the axial ligands and their solid state hydrogen bonded networks. Isothermal titration calorimetry was used to assess the difference in binding properties exhibited by the two zinc complexes at physiological pH in an aqueous environment. A series of coordinating amino acids were found to preferentially bind to the mononuclear zinc triflate (1) complex over the corresponding nitrate (2) assembly, with histidine exhibiting a two centre binding mode.

Complexation of NiII acetate with cis,trans-1,3,5-triaminocyclohexane (trans-tach) in the presence of acetic acid leads to the construction of an infinite one-dimensional nickel chain {[Ni2(trans-tachH)2(OAc)4(H2O)2](OAc)2·5H2O}n (1). The crystal structure of 1 shows the chains to be connected via hydrogen bonded interactions between the protonated trans-amine group of the trans-tach and the non-coordinated oxygen atom of the acetate group bound to the second nickel centre on the parallel chain. Magnetic studies show ferromagnetic interactions between adjacent NiII centres.

The use of a strategy combining ligand design and changes of reaction conditions has been investigated with the goal of directing the assembly of mononuclear, dinuclear, tetranuclear, and polymeric copper(II) complexes. As a result, closely related copper monomers, alkoxo dimers, and hydroxo cubanes, along with a carbonate-bridged polymeric species, have been synthesized using the rigid, aliphatic amino ligands cis-3,5-diamino-trans-hydroxycyclohexane (DAHC), cis-3,5-diamino-trans-methoxycyclohexane (DAMC), and the glutaryl-linked derivative glutaric acid bis-(cis-3,5-diaminocyclohexyl) ester (GADACE). The composition of the monomeric complex has been determined by X-ray crystallography as [Cu(DAHC)2](ClO4)2 (1), the two dimers as [{Cu(DAHC)(OMe)}2](ClO4)2.MeOH (2) and [{Cu(DAMC)(OMe)(ClO4)}2] (3), the three Cu4O4 cubanes as [{Cu(DAHC)(OH)}4](ClO4)(4).2.5MeOH (4), [{Cu(DAMC)(OH)}4](ClO4)4.H2O (5), and [{Cu2(OH)2(GADACE)}2]Cl4.2MeOH.6H2O (6), and an infinite-chain structure as [{Cu(DAHC)(CO3)}n] (7). Furthermore, the cubane structures 4 and 5 have been investigated magnetically. Our studies indicate that formation of the monomeric, dimeric, and tetranuclear DAHC and DAMC complexes can be controlled by small changes in reaction conditions and that further preorganization of the ligand moiety by linking the DAHC cores (GADACE) allows more effective direction of the self-assembly of the Cu4O4 cubane core.

Reaction of ScX3 (X=NO3-, CF3SO3-, ClO4-) with 4,4'-bipyridine-N,N'-dioxide (L) affords topologically distinct six-connected three-dimensional coordination frameworks, {[Sc(L)3](NO3)3}(infinity) (1), {[Sc(L)3](CF3)SO3)3(CH3OH)2.7(H2O)3}(infinity) (2), {[Sc(L)3](ClO4)3}(infinity) (3) and {[Sc(L)4(H2O)2](ClO4)3}(infinity) (4). Compounds 1, 2 and 3 are networks based on octahedrally co-ordinated ScO6 centres bound through six oxygen atoms from six separate N-oxide ligands L. Compounds 1 and 3 are doubly interpenetrated and have alpha-polonium-type structures of 4(12)6(3) topology based upon three intersecting (4,4) nets. The structure of 2 is unusual and shows parallel, co-planar layers of (4,4) nets connected in a criss-crossed fashion to afford a new 4(8)6(6)8 topology. In 4 only four ligands L bind to each Sc(III) centre with two additional water molecules bridging metal nodes. Significantly, the bridges formed by L do not sit in a plane and if connections through L are considered alone the resultant structure is a diamondoid array typically based upon a tetrahedral connecting node at Sc. Five interpenetrating diamondoid networks are observed that are cross-bridged by water molecules to form a single three-dimensional array of 4(8)6(7) topology. Compound 4 can also be viewed as incorporating two intersecting (4,4) grids based upon two ligands L and two bridging waters. Thus, variation of anion, solvent and conditions critically affects the structures of products formed, and the series of polymers reported herein illustrates how tectons based upon (4,4) grids can be combined and distorted to form non-NaCl topologies and even cross-bridged, multiply interpenetrated diamondoid materials. Both compounds 2 and 4 represent unusual examples of self-penetrated coordination frameworks.

Unprecedented 18-molybdosulfite Dawson clusters encapsulate two pyramidal sulfite ions as templates, and exhibit a short S⋅⋅⋅S interaction between the two ions, which was characterized by DFT calculations. The [Mo18O54(SO3)2]4− ion is the first discrete thermochromic polyoxometalate cluster: its color varies from pale yellow at 77 K to deep red at 500 K (see picture).

The reaction of cis,trans-1,3,5-triaminocyclohexane·3HX (L·3HX) with PdX2 (X = Br, Cl) affords a wide range of coordination complexes that represent the different coordination modes available to L. Monoligand complexes [Pd(LH)Cl2]Cl (1) and [Pd(LH)Br2]2[PdBr4] (2) demonstrate the bidentate coordination of L with the two cis amino ‘head’ groups chelating the palladium(II) ion and the third trans amino ‘tail’ group being protonated. Diligand complexes [Pd(LH)2]X (X = (NO3)43, (SO4)24) show a ‘head-to-head’ coordination mode with the protonated trans amino groups adopting a conformation that positions them opposite to each other. Both sets of amino groups are engaged in coordination in a cyclic ‘head-to-tail’ fashion found in the hexanuclear ring clusters [{Pd(L)X}6]X6 (X = Cl 5, Br 6). 5 and 6 are isostructural, both in the solid state and in solution, despite accommodating six chloro or bromo ligands into the cluster framework. A trinuclear complex [Pd{Pd(L)Cl2}2Cl2] (7) reveals ‘tail-to-tail’ coordination of two ligands for the centre palladium(II) ion in addition to their ‘head’ amino groups individually chelating other palladium(II) ions. Complexes 1–7 were characterised by single-crystal X-ray diffraction, elemental analysis, IR and by NMR spectroscopy (1–6).

Compounds (IV), (V), and (VII) crystallize in the triclinic space group P with Z = 1, 2, and 2, respectively (single crystal XRD).

The title compound [MoS4Cu3(dppm)3][BF4]]·2H2O (dppm=Ph2PCH2PPh2) was synthesized for nonlinear optical studies by the reaction of (Et4N)2MoS4 and [Cu2(dppm)2(MeCN)4][BF4]2 in CH3CN solution. Single-crystal X-ray analysis revealed that three copper atoms and the MoS4 2− form a distorted ‘flywheel’ array with WCu separations of 2.7754(14), 2.792(2) and 2.820 (2) A. The third-order nonlinear optical properties were investigated by a Z-scan technique with 7 ns laser pulses at 532 nm. It was observed that the nonlinear absorption is very small, but it has considerable third-order large nonlinear refractive index.

A new binuclear copper(II) complex [Cu2(H−4tapt)]·10H2O, where tapt is N,N′,N′′,N′′′-tetra(2-aminopropyl)-1,1,2,2-ethanetetraamide, has been synthesized and investigated in detail as a mimic of superoxide dismutase. Crystal structure analysis shows that each copper atom is situated in a slightly distorted square-pyramidal environment, with a water molecule at the apex. According to the result of pulse radiolysis, the complex has a high rate constant toward ˙O2−, kcat = 1.91 × 108 dm3 mol−1 s−1 (pH 7.4). Potentiometric titration shows that the mimic exhibits high stability at physiological pH value (7.4). EPR and ES-MS spectra reveal intermolecular interaction of two copper(II) nuclei.

Three zinc(II) complexes, [Zn(bipy)(dmit)]2 (1), [Zn(phen)(dmit)]2 (2) and Zn(py)(mnt) (3), where bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline, py = pyridine, H2dmit = 4,5-dimer-capto-1,3-dithiol-2-thione, mnt = maleonitriledithiolate, have been synthesized and their crystal structures determined. Complex 1 is monoclinic, space group P21/c, with a = 11.570(3), b = 9.137(3), c = 15.051(6)A, β = 109.56(2)°, Z = 2 and was refined to R 1 = 0.039. Complex 2 is monoclinic, space group P21/n, with a = 9.363(2), b = 13.732(3), c = 12.767(3), β = 94.06(3)°, Z = 2 and was refined to R 1 = 0.038. Complex 3 is orthorhombic, space group P212121, with a = 8.621(3), b = 10.546(4), c = 16.848(2), Z = 4 and was refined to R 1 = 0.040. IR and electronic absorption spectra were investigated.

The title compounds [MS 4 Cu 4 (SCN) 2 (NC 5 H 5 ) 6 ] (M=W ( 1 ); M=Mo ( 2 ) ; NC 5 H 5 =pyridine) were obtained by the reaction of (NH 4 ) 2 MS 4 , CuSCN, KSCN and pyridine. The X-ray analyses of 1 and 2 show that four edges of the tetrahedral MS 4 2− core are coordinated by four copper atoms, giving an MS 4 Cu 4 aggregate of approximate D 2 h symmetry. The nonlinear optical properties of 1 and 2 were investigated by a Z -scan technique with 7 ns laser pulses of 532 nm. The third-order nonlinearities were determined with α 2 =4.3×10 −5 and 4.1×10 −5 cm W −1 M −1 ; and n 2 =−4.3×10 −10 and −4.1×10 −10 cm 2 W −1 M −1 , respectively, for compounds 1 and 2 .

Two new O , O ′-dialkyl dithiophosphate-containing sulfido clusters, [WCu 3 S 4 (PPh 3 ) 3 {S 2 P(OCH 2 Ph) 2 }] 1 and [WAg 3 OS 3 (Ph 3 P) 3 {S 2 P(OPr i ) 2 }] 2 , were synthesized through reactions of [NH 4 ] 2 [WS 4 ] with [CuS 2 P(OCH 2 Ph) 2 ] and [NH 4 ] 2 [WOS 3 ] with [AgS 2 P(OPr i ) 2 ], respectively. Their crystal structures and nonlinear optical properties are reported. The X-ray crystallographic structure of 1 is an incomplete cubane-like structure, the dithiophosphate ligand adopts a triply bridging role, employing two sulfur atoms to coordinate to the three Cu atoms: one sulfur atom binds to one Cu atom, another sulfur atom to two other Cu atoms. The structure of 2 contains a half-open cubane-like cluster core, the dithiophosphate ligand acts as a bidentate ligand and the two S atoms of the di-isopropyl dithiophosphato ligand coordinate to two Ag atoms, respectively. Using a Z -scan technique with 532 nm laser radiation, both the real and imaginary parts of third-order nonlinear susceptibility of clusters 1 and 2 were determined.

A thiocyanate bridged one-dimensional chain copper(II) complex, {[(232-tet)Cu(NCS)]-(C104)} n , where 232-tet = N,N'-bis(2-aminoethyl)-l,3-propanediamine, has been synthesised and its crystal structure determined at room temperature. This complex crystallises in the orthorhombic system, space group Pca21, with a = 23.565(3), b = 9.011(2), c= 14.290(3)A and Z = 4. Least-squares refinement of the structure leads to conventional R 1 and wR 2 factors of 0.052 and 0.142. The asymmetric unit consists of two [(232-tet)Cu(NCS)]+ units and two per-chlorate anions. The two symmetric independent [(232-tet)Cu(NCS)]+ units form two different chains in the crystal lattice. The intrachain copper(II)-copper(lI) separations are 7.282(5) [Cu(l)-Cu(l)a, a: 1.5 - x, y, 0.5+ z] and 7.334(5)A [Cu(2)-Cu(2)b, b: 1-x,1-y,0.5 + z], respectively. The interchain copper(II)-copper(II) separation is 6.870(5) A [Cu(l)-Cu(2)b, b: 1 — x, 1 —y, 0.5+ z]. The coordination environments of the two Cu(II) atoms are similar. Each Cu(II...

CuL 5H2O (H2L = 1, 15-diaza-3, 4; 12, 13-dibenzo-5, 8, 11 -trioxacyclo-octadecane-N,N′-diacetic acid) crystallized from water. Its crystal structure was determined by X-ray diffraction analysis and refined in space group Pnma, a = 20.1784(11), b = 15.8745(9), c = 8.9266(5)A, V = 2859.4(3)A3, Z = 4, ⋋(MOKα) = 0.71073, RW . = 0.0294 for 1822 observed reflection [I > 2[sgrave](I)]. The copper atom is surrounded by two nitrogen atoms, two oxygen atoms from the carboxyl groups in the ligand and one oxygen atom from a coordinated water to form a distorted square pyramidal arrangement. The three ether oxygen atoms in the cycle have no contact with the copper ion. The stability constant for the 1 :1 complex of copper(II) and protonation constants for the ligand have been determined by potentiometric titration in water (I = 0.1, KNO3) at 25°C. Electronic spectra, conductivity measurements, thermal analysis, and the EPR of the complex are discussed in terms of the crystal structure.

Two novel palladium complexes derived from thiotungstates and 1,2-dithiolates, [NBu4]2[PdWO2S2(dmit)] (1) and [NBu4]2[PdWS4(mnt)] (2) (H2dmit = 4,5-dimercapto-1,3-dithiole-2-thione, H2mnt = 2,3-dimercapto-2-butenedinitrile), have been synthesized and characterized. X-ray diffraction analyses reveal that palladium in 1 is coordinated by a dmit (C3S52−) and a dioxothiotungstate (WO2S22−), whilst in 2 it is coordinated by a mnt (C4N2S22−) and a tetrathiotungstate (WS42−). 1 is the first structurally determined metal complex with dioxothiotungstate as ligand. Both dithiolates and thiotungstates in 1 and 2 play the role of bidentate ligands through two sulfur atoms chelating palladium atoms. The Pd–W distances are 2.917(1) and 2.896(1) A in 1 and 2, respectively. The electronic properties have been investigated by spectroscopic techniques and cyclic voltammetry. The reaction of 2 with Ag(Ph3P)2NO3 affords Pd(Ph3P)2(mnt) and Ag4W2S8(Ph3P)4.

Reaction of NiCl2 · 6H2O, Na2[i-mnt] and benzo-15-crown-5 in CH3OH⧹CH2Cl2 at room temperature leads to [{Na(benzo-15-crown-5)}2Ni(i-mnt)2]n · nCH2Cl2 (1). The same reaction with Na2[mnt] instead of Na2[i-mnt] affords [{Na(benzo-15-crown-5)}2Ni(mnt)2]n (2). Both complexes were isolated as crystalline products. X-ray diffraction analyses reveal that the main segments of 1 and 2 are infinite train structures, in which the building blocks Ni(i-mnt)2 or Ni(mnt)2 in end-to-end arrangements act as body frames and crown cycles standing by the body frames play the role of cartwheel. They are joined with each other through sodium ions.

Mercury(II) complex of 4,5-ethylenedithio-1,3-dithiole-2-thione (C5H4S5), [Hg2(C5H4S5)2Cl4]n, was synthesized and characterized crystallographically. It possesses the one-dimensional polymeric structure composed of centrosymmetric quasi-isolated binuclear subunits. The mercury atoms in zigzag arrangement achieve five-coordination in a distorted trigonal bipyramidal geometry by bonding to two bridging Cl, a terminal Cl, a thione S and a thioether S atom of C5H4S5. The S ... S contacts of 3.568(3) A between two nearby chains generate a two-dimensional network. Through S ... S interactions of 3.583(3) A between the two-dimensional layers, a three-dimensional supramolecular network is formed.

A number of processing routes were developed for the synthesis of mullite whiskers. Mullite whiskers that were derived from ytterbia-doped aluminum hydroxide-silica gel were studied; another process for preparing mullite whiskers from Al2O3-SiO2 oxide mixtures by mechanochemical method was encountered by chance. The method of ytterbia-doped aluminum hydroxide-silica was used to enhance mullite formation from gel. For adding ytterbia, mullite formation can take place at 1000 °C and almost single-phase mullite can be achieved at 1150 °C, which is a significantly lower temperature than mechanochemical method. This enhancement of mullite formation is also attributed to refinement of aluminum hydroxide-silica by gel. Furthermore, well-developed single-crystal mullite whiskers were produced from the gel powder instead of normal-shaped grains. The presence of YbO might have promoted the formation of nanosized Al2O3 particles, which then acted as a template leading to mullite whiskers at higher sintering temperature.

A series of isomalononitrile dithiolato palladium complexes, ( PPh 3 ) 2 Pd (1- mnt ) ( 1 ) , [P(OPh) 3 ] 2 Pd( i -mnt) ( 2 ), (PPh 3 )(py)Pd( i -mnt)·CH 3 CN ( 4 ), (Et 4 N) 2 Pd( i -mnt) 2 ( 4 ) and (Ph 4 As) 2 Pd( i -mnt) 2 ( 5 ) were synthesized and characterized by elemental analysis and IR spectroscopy. The reaction between (Et 4 N) 2 Pd( i -mnt) 2 ( 4 ) and (Et 4 N) 2 WS 4 gave a mixed metal cluster (Et 4 N) 2 WS 4 Pd( i -mnt) ( 6 ). The crystallographically determined structures of 1 and 6 are reported.

Two Group 6–Group 10 sulfido mixed-metal complexes, [NEt4][PdWS4(S2CNC4H8)] 1 and [NEt4]2[PdW2S8] 2, have been synthesized via reactions of [Pd(S2CNC4H8)2] with [NH4]2[WS4] and NEt4Cl in different molar ratios in dichloromethane. X-Ray crystallographic structure determinations revealed that palladium in 1 is co-ordinated by a pyrrolidinecarbodithioate and a tetrathiotungstate, while in 2 it is co-ordinated by two tetrathiotungstates symmetrically. Both dithiocarbamate and tetrathiotungstate act as bidentate ligands through two sulfur atoms chelating palladium. The Pd–W distances are 2.8669(7) and 2.9008(5) A in 1 and 2, respectively. Non-linear optical properties of the compounds were studied with a 7 ns pulsed laser at 532 nm. Compound 1 exhibits mainly optical self-defocusing (n2 = –6.8 × 10–18 m2 W–1 as measured with a 1.0 × 10–3 mol dm–3 acetonitrile solution) with negligible non-linear absorption. Compound 2 exhibits both optical self-defocusing (n2 = –7.5 × 10–18 m2 W–1, as measured with a 1.6 × 10–3 mol dm–3 acetonitrile solution) and optical non-linear absorption (α2 = 3.5 × 10–11 m W–1).