Synthesis,characterization and luminescence of the tetranuclear gold cluster: [Au4{7,8-(PPh2)2-7,8-C2B9H10}2(PPh3)2]

A tetranuclear gold cluster has been synthesized by the reaction of [Au(PPh₃)NO₃] with the closo carborane diphosphine 1,2-(PPh₂)₂-1,2-C₂B₁₀H₁₀ in THF, and characterized by elemental analysis, FT-IR, ¹H and ¹³C?NMR spectroscopy and X-ray structure determination. The cluster crystallizes in the triclinic Pī, a?=?15.118(8)?Å, b?=?16.057(9)?Å, c?=?24.284(13)?Å, α?=?80.822(9)°, β?=?79.624(8)°, γ?=?81.938(8)°, Z?=?2, R ₁?=?0.0626, wR ₂?=?0.1894. A single crystal structure determination showed that four gold atoms form a tetrahedral framework. Among these four gold atoms, two were chelated by two nido carborane diphosphine [7,8-(PPh₂)₂-7,8-C₂B₉H₁₀]^? anions coming from the degradation of the initial closo ligand 1,2-(PPh₂)₂-1,2-C₂B₁₀H₁₀, while the other two were ligated to two PPh₃ groups. The luminescence of this cluster was also investigated in dichloromethane solution at room temperature.     

1-D zigzag double-chain coordination polymers of transition metals derived from pyridine-2,3,5,6-tetracarboxylic acid

Three new 1-D zigzag coordination polymers {[M₂(pdtc)(bpy)₂(H₂O)₃]?·?4H₂O} _n [M?=?Zn (1), Ni (2), Co (3)] (H₄pdtc?=?pyridine-2,3,5,6-tetracarboxylic acid, bpy?=?2,2′-bipyridine) have been synthesized by the reactions of H₄pdtc and corresponding metal salts in the presence of bpy at room temperature and characterized by elemental analyses, IR, TGA, fluorescence, and X-ray diffraction. The main structural feature of 1–3 is the presence of octahedrally coordinated M1(II) and M2(II) centers sequentially bridged by pdtc ligands; bpy acts as a blocking ligand to avoid further polymerization. These coordination modes lead to 1-D double-chain structures. The 2-D or 3-D supramolecular structures of 1–3 are built up by π?···?π and hydrogen-bond interactions. Two (H₂O)₃ clusters are observed in 1–3. The zinc complex shows strong fluorescent emission at 325?nm.     

Pyrazine-2,3-dicarboxylate-bridged polymeric and dinuclear complexes involving decameric water clusters

Two copper(II) complexes of pyrazine-2,3-dicarboxylate (H₂pzdc) with 2-aminopyridine (apy), {(Hapy)₂[Cu(μ-pzdc)₂]} _n (1) and 1,10-phenanthroline (phen), [Cu₂(μ-pzdc)(phen)₄][N(CN)₂]₂?·9H₂O (2) have been synthesized and structurally characterized. Complex 1 consists of a pyrazine-2,3-dicarboxylate bridging across a double chain, while 2 exists as a dinuclear complex in which two Cu(II) ions are bridged by pzdc via different coordination modes. One Cu(II) ion in the binuclear complex is a distorted octahedron, while the other Cu(II) is a distorted trigonal bipyramid. A chair-like decameric water cluster composed of two pentamers and a shared-edge tetramer is detected, which further associate into a 1-D tape with dicyanamide anions by hydrogen bonds.     

Solid-state thermolysis of [MnO]12 containing molecular clusters into novel MnO nano- and microparticles

Novel MnO nano- and microparticles including spherical nanoparticles and various micropolyhedra of pyramid-like, truncated rectangular pyramid-like, cubic, and rhombic dodecahedral particles, were controllably synthesized via solid-state thermolysis of inorganic core containing molecular clusters [Mn₁₂O₁₂(O₂CR)₁₆(H₂O)₄] (R=C₆H₅, CH₃, and C₆H₅OCH₂) in a conventional horizontal tube furnace. Among them, pyramid-like, truncated rectangular pyramid-like, cubic, and rhombic dodecahedral MnO submicroscale particles were reported for the first time. The products were characterized by XRD, XPS, Raman spectrum, SEM, EDX, TEM and HRTEM. During the reaction process, thermolysis temperature, reaction time, and different molecular clusters {Mn12} precursors with different organic ligands as well play important roles in determining the sizes and shapes of the final products. The formed MnO nanospheres from [Mn₁₂O₁₂(O₂CC₆H₅)₁₆(H₂O)₄] at 400 °C for 10 h exhibited weak ferromagnetic behavior at low temperature which may be due to the size-effect of nanomaterials. Furthermore, the possible formation mechanism was also discussed.     

Two Nickel（Ⅱ） Complexes Constructed by Novel Bis（3-methoxy-2-pyridyl）ether-6,6′-dicarboxylic Acid Ligand： Lattice Water Control of Structure

Under given conditions, two complexes of [Ni（H20）2BEDA]·2H2O 1 and [Ni（Py）2- BEDA]·6H2O 2 （BEDA = bis（3-methoxy-2-pyridyl）ether-6,6′-dicarboxylic acid） have been synthesized and characterized by elemental analysis and X-ray single-crystal diffraction. Crystal data for 1： C14H18NiN2O11, monoelinic C2/c, a = 14.3844（17）, b = 12.9900（15）, c = 9.6309（11） A, β = 104.3350（10）°, V= 1743.5（4） A3, Z = 4, Dc= 1.711 g/cm^3, F（000） = 928, μ = 1.179 mm^-1, Mr= 449.01, the final R = 0.0228 and wR = 0.0625. Crystal data for 2： C24H32NiN4O13, triclinic P1, a = 9.423（2）, b = 11.863（3）, c = 13.089（3） A, α = 91.511（3）, β = 92.465（3）, γ = 100.696（2）°, V = 1435.6（6） A^3, Z = 2, Dc= 1.488 g/cm^3, F（000） = 672, μ = 0.748 mm^-1, Mr= 643.25, the final R = 0.0400 and wR = 0.0975. Interestingly, in the two complexes, lattice water molecules dominate its crystal structures. Therefore, extensive intermolecular hydrogen bonds assemble 1 and 2 into 2D extended sheets and a 3D open framework, respectively. Furthermore, water molecules present in 2 are associated to form water clusters.     

Ground‐State and Excitation Spectra of a Strongly Correlated Lattice by the Coupled Cluster Method

The coupled cluster method is applied to a strongly correlated lattice Hamiltonian, and the coupled cluster linear response method is extended to the calculation of electronic spectra by finding an approximation to a resolvent operator which describes the spectral response of the coupled cluster solution to excitation operators. In this spectral coupled cluster method, the ground and excited states appear as resonances in the spectra, and the resolvent can be iteratively improved in selected spectral regions. The method is applied to a MnO₂ plane model which corresponds to previous experimental works.     

W4Br10 Cluster Intermediates in the Solid State Nucleation of W6Br12

The new adduct W₄Br₁₀ · 2SbBr₃ and the new binary compound W₄Br₁₀ were obtained as products in a reaction cascade in which WBr₆ was reacted with elemental antimony at successively increased temperatures. The crystal structures of both compounds were refined from X‐ray powder diffraction data and their electronic structures were analyzed by MO calculations. The cluster compounds W₄Br₁₀ · 2SbBr₃ and W₄Br₁₀ appear as intermediates in the solid state nucleation of W₆Br₁₂. The overall reaction cascade involves tungsten clusters having tetrahedral (W₄), square pyramidal (W₅) and finally octahedral (W₆) cluster cores.     

Thermal stability of cluster structure in Bi x Sn1− x molten alloys in vicinity of eutectic point

Structure of liquid Bi _x Sn_{1? x} molten alloys has been studies in the vicinity of eutectic point at temperatures of complete melting and above by 100?K. It is shown that the structure parameter concentration dependences reveal the deviation from linear function with extremum points at eutectic composition. Such features exist also at higher temperatures. The reason of untypical behaviour of structure parameters is supposed to be attributed to the existence of two kinds of clusters with Sn‐ and Bi‐like structures.     

PREPARATION AND CHARACTERIZATION OF CLUSTERS CONTAINING THE CoMRuS (M=Mo OR W) CORE

Abstract

The reaction of (μ₃-S)RuCo₂(CO)₉ with functionally substituted cyclopentadienyl tricarbonyl metal anions M(CO)₃(C₅H₄C(O)R) (M = Mo, W; R = OEt, CH₂CH₂COOMe) in THF under reflux gave new chiral skeleton clusters (μ₃-S)RuCoM(CO)₈(C₅H₄C(O)R) [M = Mo, R = OEt (1); M = W, R = OEt (2); M = Mo, R = CH₂CH₂COOMe (3); M = W, R = CH₂CH₂COOMe (4)]. These complexes were characterized by elemental analysis, IR and ¹H NMR spectra. The molecular structure of compound (1) was determined by single-crystal X-ray diffraction methods.