Synthesis and characterization of mixed-metal complexes of Ag/Cu and W/Mo and a complex of Ag with heterocyclic thione ligands

Reactions of AgI with salts of [WS(4)](2-) or [MoS(4)](2-) and with either imidazolidine-2-thione (Imt) or [1,3]diazepane-2-thione (Diap) give the complexes [WS(4)Ag(2)(Imt)(2)](n) and [MS(4)Ag(2)(Diap)(4)] [M = W or Mo]; in the case of Diap, corresponding Cu complexes can be obtained with CuCl instead of AgI. Decomposition of the Ag-Diap complexes during attempted recrystallization leads to the polymeric complex [AgI(Diap)](n). The monomeric mixed-metal Diap complexes contain edge-sharing WS(4) and AgS(4) tetrahedra, the Diap ligands being terminally bonded to Ag through sulfur. The mixed-metal W-Ag-Imt complex is a chain polymer with two different environments for the WS(4) unit and three different coordination environments for Ag, one of which is an unprecedented AgS(5) square-based pyramid; Imt ligands are terminally coordinated to Ag. [AgI(Diap)](n) has a complex polymeric chain structure with three different distorted tetrahedral environments for Ag, direct Ag-Ag bonding, both bridging and terminal I, and all Diap ligands bridging pairs of Ag atoms. All the crystal structures feature N-H[...]S or N-H[...]I hydrogen bonding. The complexes have also been characterised by infrared, UV-Vis and (1)H and (13)C NMR spectroscopy.     

Synthesis,X-ray structural characterization and pyrolysis studies of heterobi- and heterotrimetallic molecular complexes

Heterobi- and heterotrimetallic complexes [NiTl(acac)₂(dmae)]₂(1) and [Ba(acac)(OH₂)Ni₂(acac)₄Tl(dmae)₂] (2) (acac = acetylacetonate, dmae = N, N-dimethyl aminoethanolate) have been synthesized by simple reactions of Ni(II) acetylacetonate, Tl(I) acetylacetonate and dmaeH for (1) and Ni(II) acetylacetonate, Tl(I) acetylacetonate, Ba metal and dmaeH for (2) in toluene to obtain crystalline products that were characterized by physicochemical and spectroscopic methods. Single-crystal X-ray analysis of both complexes shows that they crystallize in a monoclinic crystal system with space group P2₁/c. TGA studies of the complexes indicate that complex (1) is a suitable precursor for the preparation of composite NiO/Tl₂O₃, while complex (2) yields an unstable composite NiO/Tl₂O₃/BaO which on exposure to air is converted to NiO/Tl₂O₃/BaCO₃ by the absorption of atmospheric carbon dioxide.     

Synthesis and characterization of a polyoxovanadate cluster representing a new topology

A new type of mixed-valence polyoxoanionic cluster, [V(V)13V(IV)3O42(Cl)]8-, composed of 14 {VO5} square pyramids and 2 {VO4} tetrahedral units, hosting a chloride ion has been synthesized and characterized.     

Synthesis and structural characterization of a new trimetallic thiocubane cluster

The trimetallic cluster W2CuAgS4(TDT)2(PPh3)2-CH2Cl2 (TDT= [S2(C6H3)CH3]2-) (2) has been prepared from the reaction of the well-defined molecule building block [W2S4(TDT)2]2-(1) with AgNO3,CuBr and PPh3.The structure contains a [W2CuAgS4]4+ distorted cubane-like core.Two types of metal-metal bonds exist in the core.One is W-W bond of which length is 0.2871(1) nm,the other is W-M' (M'=Cu or Ag) bonds,whose mean distance is 0.2980 nm.The details of synthesis,structure,IR,UV-Vis and 31P NMR spectra are reported.The crystallographic data are:space group F21/n,with 0=1.6987(4),6=1.7763(6),c=1.8918(5) nm,β=98.54(2)°,V=5.645(3) nm3,Z=4,and final R=0.043 for 6437 observed reflections.     

Ag/Cd coordination architecture and photoluminescence behaviors

Three coordination architectures, {[Ag₄(pbmb)₄·(BF₄)₄](CH₃OH)₂·H₂O}_n (1), {[Cd₂(pbmb)₄](ClO₄)₄·(CH₃OH)₅}_n (2), and [Cd₄(pbmb)₄·I₈(CH₃OH)₂]_n (3) (pbmb = 1-((2-(pyridin-2-yl)-1H-benzoimidazol-1-yl)methyl)-1H-benzotriazole), are built up from Ag(I)/Cd(II) salts and a flexible pyridyl-benzimidazole-based organic spacer. Single-crystal analysis shows that 1 and 2 have 1-D chains, while 3 displays a tetranuclear structure. All complexes exhibit different coordination geometries and properties, which can be attributed to the difference between the metal centers or anions. In the case of 1 in particular, the Ag?Ag interactions play a crucial role in the formation of a supramolecular architecture. The binuclear-based complex consists of a pair of Ag?Ag contacts (ca. 2.953 Å), and it exhibits intense triplet emission with large Stokes shift and high thermal stability. Compared to pbmb, 2 has excellent high-energy fluorescence properties, while 1 and 3 exhibit mainly low-energy emission. Therefore, it can be concluded that the heavy atom effect has a causative influence in enhancing the triplet state radiative rate, resulting in large Stokes’ shift of the complex.     

Synthesis,characterization and antibacterial properties of a novel nanocomposite based on polyaniline/polyvinyl alcohol/Ag

In this study, a novel nanocomposite based on polyaniline/polyvinyl alcohol/Ag (PANI/PVA/Ag) has been successfully synthesized. The chemical reduction method was used to produce Ag nanoparticle colloidal solution from Ag⁺ ions. The polymerization of aniline occurred in situ for the preparation of polyaniline (PANI) in the presence of ammonium persulfate. With exposure to Ag nanoparticles on the PANI/PVA composite, a new nanocomposite was obtained. The morphology and particle size of the novel nanocomposite was studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) analyses. According to XRD analysis, the size of nanoparticles was found to be in the range of 10–17 nm. SEM images showed the favored shape of nanoparticles as triangle which is a benign shape for antibacterial analysis. The antibacterial activity of the obtained nanocomposite was also evaluated against Gram positive bacteria Staphylococcus aureus (Staph. aureus) and Gram negative Escherichia coli (E. coli) using the paper disk diffusion method. The antibacterial study showed that the PANI/PVA composite did not have a very good antibacterial activity but PANI/PVA/Ag nanocomposites were found to be effective against two bacteria.     

Synthesis and characterization of a novel tantalum chalcogen-rich molecular cluster with square planar metal core

Black single crystals of Ta(4)Se(9)I(8) are obtained in a high yield by heating Ta, Se, and I(2) at 300 degrees C in 1:2.2:1.0 molar ratio. In the structure, the tantalum atoms form a square, with four Se(2) ligands bridging the Ta-Ta edges and one capping the square. Each Ta atom has two terminal iodine atoms. The compound is diamagnetic and has only two electrons for metal-metal bonding.     

具有可见光催化活性的Ag_3PO_4/NaNbO_3复合材料的合成与表征

采用共沉淀法制备了Ag_3PO_4/NaNbO_3复合半导体光催化剂,利用X-射线衍射、X射线光电子能谱、紫外漫反射和扫描电镜等方法对合成样品进行表征.测试了样品对亚甲基蓝溶液的光催化降解活性,复合材料的催化活性远高于单体的Ag_3PO_4和NaNbO_3.     

Synthesis,crystal structure,and characterization of a new high-dimensional phosphomolybdate architecture built from silver-complex fragments and hexa-connected P2Mo5 clusters

A new 3-D organic–inorganic hybrid phosphomolybdate, [Ag(bipy)]₄(H₂P₂Mo₅O₂₃) · 3H₂O (1) (bipy = 4,4′-bipyridine) has been hydrothermally synthesized and characterized by elemental analyses, IR, TG, and fluorescent properties. Compound 1 crystallizes in the monoclinic space group C2/c with a = 23.830(5), b = 21.030(4), c = 24.501(5) Å, β = 110.38(3)°, V = 11510(4) ų, Z = 8, and R ₁ (wR ₂) = 0.0507 (0.1210). It contains unique 3-D metal organic frameworks based on silver-complex fragments and hexa-connected P₂Mo₅ clusters via covalent bonds and represents the highest connection numbers of P₂Mo₅ clusters to date.     

Synthesis and X-ray characterization of the phosphido-carbonyl cluster anions

The [Co(9)P(CO)(21)](2)(-) anion has been isolated from the products of the reaction between Na[Co(CO)(4)] and PCl(5) in tetrahydrofuran at reflux. The structure of the cluster anion [Co(9)P(CO)(21)](2)(-) in its tetraphenylphosphonium salt has been elucidated by X-ray analysis. The crystals are monoclinic, space group P2(1)/n, a = 12.528(3), b = 14.711(5), c = 19.312(6) A, beta = 93.68(2) degrees, Z = 2. Final R = 0.065 for 2300 unique reflections having I > 3sigma(I). The anion, which is disordered about an inversion center, consists of a monocapped square antiprismatic cluster containing an interstitial phosphide and surrounded by 13 terminal and 8 edge-bridging carbonyl ligands. Average values are: Co-Co 2.685 A, and Co-P 2.256 A. The [Co(10)P(CO)(22)](3)(-) anion has been obtained by condensation of the [Co(9)P(CO)(21)](2)(-) anion with [Co(CO)(4)](-) in tetrahydrofuran at reflux. While the [Co(9)P(CO)(21)](2)(-) anion is stable under CO, the [Co(10)P(CO)(22)](3)(-) anion is decomposed to [Co(9)P(CO)(21)](2)(-) and [Co(CO)(4)](-). The benzyltrimethylammonium salt of the [Co(10)P(CO)(22)](3)(-) anion has been studied by X-ray analysis. It gives triclinic crystals, space group P_1, a = 11.452(3), b = 23.510(6), c = 25.606(4) A, alpha = 112.46(1), beta = 95.79(1), gamma = 73.548(2) degrees, Z = 4. Final R = 0.041 for 8600 unique reflections having I > 3sigma(I). There are two independent trianions in the asymmetric unit, both showing similar geometries, consisting of bicapped square antiprismatic clusters with a central P atom, each bearing 10 terminal and 12 edge-bridging carbonyl ligands, 8 of which, bound to the capping metals, are markedly asymmetric. Average values are: Co-Co 2.678 A, and Co-P 2.262 A. Electrochemistry shows that [Co(9)P(CO)(21)](2)(-) and [Co(10)P(CO)(22)](3)(-) in acetonitrile solution undergo either a one-electron oxidation or a two-electron reduction. This latter process appears as a single step in the case of the dianion and as two separated one-electron steps in the case of the trianion. All the processes are accompanied by slow chemical complications, thus testifying that no stable redox congeners exist for these phosphide clusters.     

Synthesis and structural characterization of the novel cluster compound

Reaction of [Mo3Y(mu-S)3(dtp)4(H2O)] (Y = O, S; dtp = S2P(OC2H5)2(-)) with HgI2 gave the novel compound [[Mo3S7(dtp)3]4 x I][(HgI3)3] x 4H2O (1), which contains a [[Mo3S7(dtp)3]4 x I] tetramer and (HgI3)-. Compound 1 has been characterized by IR, Raman, UV/Vis, and NMR spectroscopy and single-crystal X-ray diffraction analysis. It is shown that this formation process can be referred to as a new cluster reaction. The structure and spectroscopic data of the tetramer is also compared with that of the related discrete cluster [Mo3S7(dtp)3 x I]. Crystal data: space group F23, a = 26.786(3) A, V = 19218.7(4) A3, Z = 4, R = 0.059.     

Synthesis,structure, and magnetic properties of heterotrimetallic tetranuclear complexes

Two novel heterotrimetallic tetranuclear complexes [Cu(H₂L)(CH₃OH)]₂Gd(DMF)Fe(CN)₆·2H₂O·DMF (1) and [Cu(H₂L)(CH₃OH)]₂Tb(H₂O)_0.57(DMF)_0.43Fe(CN)₆·5.5H₂O (2) are reported (H₄L = N,N′-ethylenebis(3-hydroxysalicylidene)). The central Ln(III) ion is surrounded by two neutral [Cu(H₂L)(CH₃OH)] moieties, forming a Cu₂Ln trinuclear unit. The [Fe(CN)₆]^3? anion is weakly coordinated to one Cu(II) ion of [Cu(H₂L)(CH₃OH)] through a cyanide nitrogen atom with the N–Cu distance of ca. 3.2 Å. Magnetic susceptibility measurements indicate the presence of overall ferromagnetic interactions in complexes 1 and 2. The magnetic coupling constant in complex 1 is J _Cu1Gd1 = 4.54 cm^?1 and J _Cu2Gd1 = 7.97 cm^?1 based on \( \hat{H} = - 2J_{\text{Cu1Gd1}} \hat{S}_{\text{Cu1Gd1}} - 2J_{\text{Cu2Gd1}} \hat{S}_{\text{Cu2Gd1}} \) . Dynamic AC magnetic susceptibility studies reveal that complex 2 shows frequency-dependent out-of-phase signals, typical of single molecule magnet behavior. The energy barrier for complex 2 under a 2 kOe applied DC magnetic field is 13 K.     

Construction of a novel Mo/Cu/S cluster with a closed double-cubane-like polyhedron and a chain polymer of W/Cu/S clusters

Reaction of [MoOS(3)](2)(-) and [WS(4)](2)(-) with Cudtp (dtp = diethyl dithiophosphate) gave rise to the clusters [Bu(4)N](2)[(MoOS(3))(4)Cu(12)(dtp)(6)], 1, and [Et(4)N][(WS(4)Cu(4))(dtp)(3)], 2, respectively. In cluster 1, the dtp- ligands act as both monodentate and bidentate ligands that bridge between Cu atoms and link together a closed double-cubane-like [Mo(2)O(2)S(6)Cu(6)](2+) core and two incomplete cubane-like [MoOS(3)Cu(3)]+ units. In cluster 2, the [WS(4)Cu(4)](2+) fragments were connected via bidentate and doubly bridging dtp- bridges to give a chain polymeric anion. Cluster 1 is the first example of a Mo/Cu/S cluster that contains a closed double-cubane-like structure. Compound 2 is also rare and the first W/Cu/S polymer with dtp- linkages.     

Synthesis and characterization of a novel (μ3-oxo)tetraruthenium cluster

A novel (μ₃-oxo)tetraruthenium cluster (2) was synthesized in an isolated yield of 73% by the reaction of a zerovalent ruthenium complex, Ru(η⁶-cot)(η²-dmfm)₂ (1) [cot = 1,3,5-cyclooctatriene, dmfm = dimethyl fumarate], with water under reflux in 1,4-dioxane for 6 h. The structure and the X-ray characterization of this novel complex 2 as well as a possible formation mechanism of 2 are disclosed.     

Three New Structural Types of Mo/Ag/S Polymeric Complexes

Wavelike, zigzag, and helical polymers are formed by the reaction of [MoS₄]²⁻, Ag₂S, and a complementary cation. The framework of the polymeric anions depends on the valence state of the latter. For example, the butterfly-type anionic chain shown in the picture is formed upon use of a divalent cation. There is a general tendency that a higher valence state of the cation will induce a more compact chain structure.     

Rb5Mo27Se31, a novel ternary reduced molybdenum selenide containing Mo12 and Mo15 clusters

The crystal structure of Rb₅Mo₂₇Se₃₁, penta­rubidium hepta­cosa­molybdenum hentria­conta­selenium, consists of a mixture of Mo₁₂Se₁₄Se₆ and Mo₁₅Se₁₇Se₆ cluster units in a 1:1 ratio. Both types of cluster are interconnected through inter‐unit Mo—Se bonds. Rb⁺ cations occupy large voids between the different cluster units.     

Synthesis and characterization of surface-enhanced Raman scattering tags with Ag/SiO2 core-shell nanostructures using reverse micelle technology

A novel simplified method for synthesis of surface-enhanced Raman scattering tags has been reported. This synthesis method is based on reverse micelle technique using Igepal CO-520 as a surfactant and the mixed solution of silver nitrate and rhodamine dyes with isothiocyanate group as water pool followed by hydrazine hydrate reduction and TEOS polymerization leading to the formation of silica layer surrounding the silver core. Compared to the method reported in literature, the proposed methodology eliminates the necessity of vitrophilic pretreatment and makes it possible to complete all different processes including the preparation of silver nanoparticles, the conjugation of dye molecules and the formation of silica shell in the microreactor. The nanoparticle-based surface-enhanced Raman tags obtained are composed of silver core conjugated with rhodamine dyes and an encasing silica shell. Both the dyes themselves and the Ag/SiO2 core-shell nanoparticles without the encapsulation of dyes exhibit no Raman signals. However, the Ag/SiO2 core-shell nanoparticles exhibit strong Raman signals when encapsulated with these dyes. This is due to the appearance of fluorescence quenching and surface-enhanced Raman scattering effect resulting from the conjugation of dyes and silver core. The Raman tags were characterized using transmission electron microscopy (TEM), UV-visible absorption spectrometry, and Raman spectrometry.     

Synthesis of a molecular Mo2Fe6S9 cluster with the topology of the PN cluster of nitrogenase by rearrangement of an edge-bridged Mo2Fe6S8 double cubane

The structures of the P cluster and cofactor cluster of nitrogenase are well-defined crystallographically. They have been obtained only by biosynthesis; their chemical synthesis remains a challenge. Synthetic routes are sought to the P cluster in the P(N) state in which two cuboidal Fe(3)S(3) units are connected by a mu(6)-S atom and two Fe-(mu(2)-S(Cys))-Fe bridges. A reaction scheme affording a Mo(2)Fe(6)S(9) cluster in molecular form having the topology of the P(N) cluster has been devised. Reaction of the single cubane [(Tp)MoFe(3)S(4)Cl(3)](1)(-) with PEt(3) gives [(Tp)MoFe(3)S(4)(PEt(3))(3)](1+) (2), which upon reduction with BH(4)(-) affords the edge-bridged all-ferrous double cubane [(Tp)(2)Mo(2)Fe(6)S(8)(PEt(3))(4)] (4) (Tp = tris(pyrazolylhydroborate(1-)). Treatment of 4 with 3 equiv of HS(-) produces [(Tp)(2)Mo(2)Fe(6)S(9)(SH)(2)](3)(-) (7) as the Et(4)N(+) salt in 86% yield. The structure of 7 is built of two (Tp)MoFe(3)(mu(3)-S)(3) cuboidal fragments bridged by two mu(2)-S atoms and one mu(6)-S atom in an arrangement of idealized C(2) symmetry. The cluster undergoes three one-electron oxidation reactions and is oxidatively cleaved by p-tolylthiol to [(Tp)MoFe(3)S(4)(S-p-tol)(3)](2)(-) and by weak acids to [(Tp)MoFe(3)S(4)(SH)(3)](2-). The cluster core of 7 has the bridging pattern [Mo(2)Fe(6)(mu(2)-S)(2)(mu(3)-S)(6)(mu(6)-S)](1+) with the probable charge distribution [Mo(3+)(2)Fe(2+)(5)Fe(3+)S(9)](1+). Cluster 7 is a topological analogue of the P(N) cluster but differs in having two heteroatoms and two Fe-(mu(2)-S)-Fe instead of two Fe-(mu(2)-S(Cys))-Fe bridges. A best-fit superposition of the two cluster cores affords a weighted rms deviation in atom positions of 0.38 A. Cluster 7 is the first molecular topological analogue of the P(N) cluster. This structure had been prepared previously only as a fragment of complex high-nuclearity Mo-Fe-S clusters.     

Synthesis and molecular and electronic structures of a series of Mo3CoSe4 cluster complexes with three different metal electron populations

The synthesis, crystal structure, and magnetic properties of [Mo 3(CoCO)Se 4(dmpe) 3Cl 3] ( 1), [Mo 3(CoCl)Se 4(dmpe) 3Cl 3] ( 2), and [Mo 3(CoCl)Se 4(dmpe) 3Cl 3](TCNQ) ([ 2](TCNQ)) (dmpe = 1,2-bis(dimethylphosphanyl)ethane; TCNQ = 7,7,8,8-tetracyanoquinomethane) cubane-type complexes with 16, 15, and 14 metal electrons, respectively, are reported. These compounds complete the series of cobalt-containing Mo 3CoQ 4 (Q = S, Se) cubane-type complexes, which allows a complete analysis of the consequences of replacing the inner chalcogen and the metal electron count on the structural, magnetic, and electrochemical properties. The experimental evidence is theoretically supported and rationalized on the basis of density-functional theory calculations. For the 15-metal electron [Mo 3(CoCl)Se 4(dmpe) 3Cl 3] complex with S = (1)/ 2, both electron paramagnetic resonance and theoretical studies give support to a spin density mainly located on the heteroatom. The nature of the highest occupied molecular orbital upon chalcogen exchange within the Mo 3CoQ 4 (Q = S, Se) series remains essentially unchanged, whereas the nature of the ligand attached to Co (Cl or CO) results in a different ordering of the molecular orbital scheme. This behavior is explained by the absence of backdonation between an occupied d orbital of Co to an empty pi* Cl orbital, to yield frontier orbitals that differ from those of previous models.