Synthesis, structure and benzannulation of chalcogen-tethered Fischer carbene complexes

Addition of PhSH-NEt₃ or PhSeNa to PhCCC(OC₂H₅)M(CO)₅ [M = Cr or W] afforded stable, β-chalcogenide tethered conjugated carbene complexes 3-6 as a mixture of E,Z-isomers. The Z-configuration was ascribed to those isomers that readily yield cyclometallated complexes. Aminolysis with methylamine yielded corresponding amino carbene complexes as mixtures of E,Z-isomers. Alkylation by methyl iodide afforded separable E,Z-isomers of dimethylamino complexes. One-step aminolysis of ethoxy carbene complexes with dimethylamine furnished only the Z-isomer of the dimethylamino complex. The Z-isomer of dimethylamino carbene complexes yielded cyclometallated products on warming. Representative crystal structures of these complexes confirm isomer assignments. Only E-isomers of the S or Se-tethered ethoxy complexes undergo benzannulation reaction with alkynes, with loss of chalcogenide atom.     

Metallaheteroborane clusters of group 5 transition metals derived from dichalcogenide ligands

Treatment of group 5 metal polychlorides such as, [Cp_nMCl_4-x] (M = V: n, x = 2; M = Nb: n = 1, x = 0), or [Cp∗TaCl₄] (Cp = η⁵-C₅H₅, Cp∗ = η⁵-C₅Me₅), with [LiBH₄·THF] followed by thermolysis in the presence of diphenyl diselenide yielded metallaheteroborane clusters [{CpV(μ-SePh)}₂(μ-Se)], 1 [(CpNb)₂B₄H₉(μ-SePh)], 2 and [(Cp∗Ta)₂B₄H₁₁(SePh)], 3 in modest yields. Compound 1 is an organovanadium selenolato cluster in which two (CpV) moieties bridged by (μ-Se) and two (μ-SePh) ligands. Compound 2 exhibits a bicapped tetrahedral core with one (μ-SePh) ligand. 3 is a tantalahexaborane cluster in which one of the terminal BH protons is substituted by SePh. Compounds 1-3 have been characterized by mass spectrometry, ¹H, ¹¹B, ¹³C NMR spectroscopy, and the geometric structures were unequivocally established by crystallographic analysis of 1-3.     

Reactions of nido-1,2-(Cp*RuH)2B3H7 with RCCR′ (R, R′=H, Ph; Me, Me) to yield novel metallacarboranes

Addition of the internal alkyne, 2-butyne, to nido-1,2-(Cp*RuH)₂B₃H₇ (1) at ambient temperature produces nido-1,2-(Cp*Ru)₂(μ-H)(μ-BH₂)-4,5-Me₂-4,5-C₂B₂H₄ (2), nido-1,2-(Cp*RuH)₂-4,5-Me₂-4,5-C₂B₂H₄ (3), and nido-1,2-(Cp*RuH)₂-4-Et-4,5-C₂B₂H₅ (4), in parallel paths. On heating, 2, which contains a novel exo-polyhedral borane ligand, is converted into closo-1,2-(Cp*RuH)₂-4,5-Me₂-4,5-C₂B₃H₃ (5) and nido-1,6-(Cp*Ru)₂-4,5-Me₂-4,5-C₂B₂H₆ (6) the latter being a framework isomer of 3. Heating 2 with 2-butyne generates nido-1,2-(Cp*RuH)₂-3-{CMeCMeB(CMeCHMe)₂}-4,5-Me₂-4,5-C₂B₂H₃ (7) in which the exo-polyhedral borane is triply hydroborated to generate a boron bound ---CMeCMeB(CMeCHMe)₂ cluster substituent. Along with 3, 4, 5, 6, and 7, the reaction of 1 with 2-butyne at 85 °C gives closo-1,7-(Cp*Ru)₂-2,3,4,5-Me₄-6-(CHMeCH₂Me)-2,3,4,5-C₄B (8). Reaction of 1 with the terminal alkyne, phenylacetylene, at ambient temperature permits the isolation of nido-1,2-(Cp*Ru)₂(μ-H)(μ-CHCH₂Ph)B₃H₆ (9) and nido-1,2-(Cp*Ru)₂(μ-H)(μ-BH₂)-3-(CH₂)₂Ph-4-Ph-4,5-C₂B₂H₄ (11). The former contains a Ru---B edge-bridging alkylidene fragment generated by hydrometallation on the cluster framework whereas the latter contains an exo-polyhedral borane like that of 2. Thermolysis of 11 results in loss of hydrogen and the formation of closo-1,2-(Cp*RuH)₂-3-(CH₂)₂Ph-4-Ph-4,5-C₂B₃H₃ (12).     

Direct insertion of sulfur, selenium and tellurium atoms into metallaborane cages using chalcogen powders

Reaction of [(η⁵-C₅Me₅)MCl₄], 1-2 (1: M = Mo and 2: W) with six fold excess of [LiBH₄·thf] followed by thermolysis with excess chalcogen powders (S, Se and Te) yielded dichalcomolybda- and tungstaboranes, [(η⁵-C₅Me₅M)₂B₄H₄E₂], 5-8 (5: M = Mo, E = S; 6: M = Mo, E = Se; 7: M = Mo, E = Te; 8: M = W, E = Se) in modest yields. The geometry of 5-8 resembles a hexagonal bipyramid with a missing connectivity of two chalcogen vertices and a very short cross cage metal-metal bonding. All these new dichalcometallaboranes have been characterized by mass, ¹H, ¹¹B, ¹³C NMR spectroscopy, and the structural types were unequivocally established by crystallographic analysis of compound 6.     

Reaction of nido-1,2-(CpRuH)2B3H7 with ethynylferrocene to yield new metallacarboranes

Addition of ethynylferrocene to nido-1,2-(Cp^∗RuH)₂B₃H₇ (1) at ambient temperature leads to nido-1,2-(Cp^∗Ru)₂(1,5-μ-C{Fc}Me)B₃H₇ (2, 3) and closo-4-Fc-1,2-(Cp^∗RuH)₂-4,6-C₂B₂H₃ (4). Compounds 2 and 3 represent a pair of geometric isomers, nido-species in which the regiochemistry of the alkyne reduction conforms to the Markovnikoff rule. Compound 4 is an octahedral structure in which the inserted alkyne is on an open face of the closo cluster.     

Synthesis and characterization of diphosphine bridged homo and heterometallic clusters containing chalcogen as “naked” atoms

Room temperature reactions of [Fe₃Te₂(CO)₈(PPh₃)] (2) and [(CO)₆Fe₂PdY₂(PPh₃)₂] (Y = Se (6), Te (7)) with bis-(diphenylphosphino)methane (dppm) in dichloromethane solution led to the formation of a tellurium bridged cluster, [Fe₃Te₂(CO)₈(μ-dppm)] (4) and mixed metal clusters, [(CO)₁₂Fe₄Y₄Pd₂(dppm)₂] (Y = Se (8), Te (9)) respectively. In both the reactions, diphosphine incorporation has taken place by replacing one or two triphenylphosphine ligand. The structures of compounds 4, 6 and 9 were established crystallographically.     

3-Pyridylacetonitrile-ligated 11-vertex rhodathiaboranes: synthesis,characterization, and X-ray crystal structure

The reaction between the 11-vertex rhodathiaborane [8,8-(PPh₃)₂-nido-8,7-RhSB₉H₁₀] (1) and 3-pyridylacetonitrile affords the hydrorhodathiaborane [8,8,8-(PPh₃)₂H-9-(3-Py-CH₂CN)-nido-8,7-RhSB₉H₉] (2) in good yield. Treatment of this cluster with ethylene leads to the formation of red, [1,1-(PPh₃)(η²-C₂H₄)-3-(3-Py-CH₂CN)-closo-1,2-RhSB₉H₈] (3). Both 11-vertex polyhedral boron-based clusters have been characterized by multielement NMR spectroscopy. In addition, (3) has been analyzed by single-crystal X-ray diffraction analysis and is only the second ethylene-ligated metalla-heteroborane to be characterized in the solid state. The molecular structure of this cluster is based on an octadecahedron. In the crystal lattice, the individual clusters form layers supported by short edge-to-face π-interactions between the phenyl rings of neighboring molecules.     

醇体系中合成CuGaS2纳米晶及其形貌演变

Using ethylene glycol as solvent and reductant, CuCl2·2H2O, (NH2)2CS and self-prepared GaCl3 as the starting materials, CuGaS2 nanostrucutures were synthesized on a large scale at 220 ℃. Powder X-ray diffraction,transmission electron microscopy, field-emission scanning electron microscope, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy were used to characterize the products. It demonstrated the evolution of the CuGaS2 particles from spherical assemblies to flowerlike morphology, over time,at 220 ℃. Simultaneously, we elucidated the specific roles of reaction temperature, reaction time and solvent in the formation of the final CuGaS2 nanostructures. A possible formation mechanism of CuGaS2 nanostrucutures was also discussed. The room temperature photoluminescence spectrum showed blue-shift and an increase of intensity, with a decrease in the sizes of CuGaS2 particles.     

双功能钛硅分子筛的合成、表征及催化性能

以四丙基溴化铵为模板剂, 硅溶胶为硅源, 正丁胺为碱源, 采用水热合成的方法, 将三价离子(Al³⁺, B³⁺或Fe³⁺)和Ti⁴⁺同时引入到MFI型分子筛的骨架, 得到同时具有氧化和酸催化活性的双功能钛硅分子筛M-TS-1(M=Al, B或Fe). 通过X射线粉末衍射、傅里叶变换红外光谱、紫外-可见漫反射光谱、氨程序升温脱附、电感耦合等离子体原子发射光谱和N₂吸附-脱附等温线手段对样品进行了表征. 结果表明, 三价离子的引入, 提高了TS-1的酸强度和酸量. 采用乙烯选择氧化为探针反应考察了M-TS-1的催化性能. 结果表明, Al-TS-1和B-TS-1在乙烯环氧化及后续的开环溶剂解反应中表现出较高的催化性能, H₂O₂的转化率在95%以上, H₂O₂的利用率大于90%, 乙二醇和乙二醇单甲醚的总收率可达10%以上.     

Reactions of pentaborane(9) with electron-rich molybdenum and tungsten phosphine polyhydrides

Reaction of [W(PMe₂Ph)₃H₆] with pentaborane(9) gives nido-2-[W(PMe₂Ph)₃H₂B₄H₈] (1) as well as nido-2-[W(PMe₂Ph)₃HB₅H₁₀] (2). The crystal structure of (2) has been determined. Compound (2) has a novel metallaborane structure containing an edge-bridging {BH₃} group between the tungsten atom and one of the basal boron atoms in a “nido-WB₄” pyramid. Reaction of [W(PMe₃)₄(η²-CH₂PMe₂)H] with pentaborane(9) gives nido-2-[W(PMe₃)₃H₂B₄H₈] (3) whilst reaction of [Mo(L)₄H₄] with pentaborane(9) gives nido-2-[Mo(L)₃H₂B₄H₈] [L = PMe₃ (4), PMe₂Ph (5)]. Treatment of [Mo(PMe₃)₄H₄] with excess BH₃ · thf gives the known borohydride [Mo(PMe₃)₄H(η²-BH₄)].     

Formation of ferraboranes from pentaborane(9) or BH3 · thf and an electron-rich cyclopentadienyl iron phosphine hydride

[(η⁵-C₅R₅)Fe(PMe₃)₂H] (R = H, Me) can be made in good yields in a simple one-pot reaction between FeCl₂, PMe₃, C₅R₅H (R = H, Me) and Na/Hg in thf. Reaction of [(η⁵-C₅H₅)Fe(PMe₃)₂H] with pentaborane(9) gives the known metallaborane [(η⁵-C₅H₅)-nido-2-FeB₅H₁₀] (1) in improved yield as well as the new metallaboranes [(η-C₅H₅)-nido-2-FeB₅H₈{μ-5,6-Fe(η⁵-C₅H₅)(PMe₃)(μ-6,7-H)}] (2), [(η-C₅H₅)(PMe₃)-arachno-2-FeB₃H₈] (3), [(η⁵-C₅H₅)₂-capped-nido-2,3-Fe₂B₄H₈] (4), [(η⁵-C₅H₅)-nido-2-FeB₄H₇(PMe₃)] (5) and [(η⁵-C₅H₅)-nido-2-FeB₅H₈(PMe₃)] (6). Reaction of [(η⁵-C₅Me₅)Fe(PMe₃)₂H] with pentaborane(9) gives predominantly [(η⁵-C₅Me₅)-nido-2-FeB₅H₁₀] (7) and [(η⁵-C₅Me₅)(PMe₃)-arachno-2-FeB₃H₈] (8). Reaction of [(η⁵-C₅H₅)Fe(PMe₃)₂H] with 2 equiv. of BH₃ · thf gives low yields of ferrocene and compound 3. Compound 7 thermally isomerises to the apical isomer [(η⁵-C₅H₅)-nido-2-FeB₅H₁₀] (9) in low yield. Compounds 1 and 7 deprotonate cleanly in the presence of KH at the unique B-H-B bridge to give [(η⁵-C₅H₅)-nido-2-FeB₅H₉⁻][K⁺] (10) and [(η⁵-C₅Me₅)-nido-2-FeB₅H₉⁻][K⁺] (11) respectively, whilst 6 deprotonates more slowly at one of two equivalent B-H-B bridges to give the fluxional anion [(η⁵-C₅H₅)-nido-2-FeB₅H₇(PMe₃)⁻] (12).     

Partial incorporation of a cyclopentadienyl ligand into a molybdaborane to form a molybdacarbaborane

Reaction of the molybdaborane arachno-2-[Mo(η-C₅H₅)(η⁵:η¹-C₅H₄)B₄H₇] (I) with NEt₃ in toluene at 120 °C for 7 days gives a 90% yield of the molybdacarbaborane nido-1-[Mo(η-C₅H₅)(η³:η²-C₃H₃)C₂B₃H₅] (II). Two of the carbon atoms in the substituted cyclopentadienyl ring in I are incorporated into the metallacarbaborane cluster II. The carbaborane {C₂B₃H₅} fragment in II is attached to an allylic {C₃H₃} group and can be thought of as a new non-planar {C₅B₃H₈} ligand providing seven electrons to the molybdenum atom. Reaction of I with KH in thf at 20 °C gives the anion via deprotonation of a B-H-B bridging proton.     

Synthesis and characterization of boronates derived from non-symmetric amino-bis-phenols

The condensation of 2-[[(2-hydroxyphenyl)amino]methyl]-phenols (1a-1e) with different arylboronic acids led to 12 new monomeric boronates of the type 2-aryl-dibenzo[d,h]-6-aza-1,3-dioxa-2-boracyclononene (2a-2l). The boronates were characterized by ¹H-, ¹³C-, ¹¹B- and 2D-NMR experiments, FT infrared, mass spectra and elemental analyses. The stereochemistry of the H-N → B-Ph fusion is always cis, as established through the NMR spectra, as well as the X-ray structures of four boronates (2a, 2e, 2f and 2l). Hydrogen bonds between the amine proton and the oxygen ester of the five- membered ring are present in three X-ray structures (2a, 2e and 2f), while the supramolecular structure in the derivative possessing a primary amine (2l) is built up through the protons present in this moiety instead of the proton from the H-N → B-Ph fragment.     

Metal fragment exchange from a molybdaborane to a tungstaborane

Reaction of the molybdaborane arachno-2-[Mo(η-C₅H₅)(η⁵:η¹-C₅H₄)B₄H₇] (I) with the electron-rich molecule [W(PMe₃)₃H₆] at 60 °C for 12 h in toluene gives the novel tungstaborane nido-2-W(PMe₃)₃H₂B₄H₇[Mo(η-C₅H₅)(η⁵:η¹-C₅H₄)H₂] (II) in 60% yield. The reaction is almost quantitative when followed by NMR. This is a rare example of metal fragment exchange within a metallaborane cage. The molybdenum atom is retained in the molecule via a σ-bond between the substituted cyclopentadienyl ring and a basal boron atom in the metallaborane cluster.     

单核镥取代的砷钨酸盐的合成、结构及表征

以双缺位结构钨酸盐K_(14)[As_2W_(19)O_(67)(H_2O)]为多酸前驱体与LuCl_3·6H_2O和2,6-吡啶二羧酸在常规水溶液中反应,制得了一例单核镥夹心的砷钨酸盐稀土衍生物K_8H_3[Lu(H_2O)_2(As_2W_(19)O_(67))(H_2O)]·39H_2O(1),并通过X射线单晶衍射、红外光谱、热重分析等方法对该化合物进行了测试和表征.X射线单晶衍射分析表明,化合物1属于单斜晶系,P-1空间群,晶胞参数a=1.253 54(9)nm,b=1.757 83(13)nm,c=2.111 40(16)nm,α=73.326 0(10)°,β=85.721 0(10)°,γ=89.856 0(10)°.该聚阴离子是由一个镥离子镶嵌在[As_2W_(19)O_(67)(H_2O)]~(14-)({As_2W_(19)})阴离子的缺位处构成的;热重分析结果表明,化合物1阴离子结构在400℃以内是对热稳定的.     

Synthesis and structural characterisation of a novel tris-methylene bridged compound (NO) 4Fe2 Se(μ-CH2)3

The tris-methylene bridged compound (NO)₄Fe₂Se(μ-CH₂)₃ has been isolated. It has been characterised by IR and ¹H, ¹³C, and ⁷⁷Se NMR spectroscopy. Its structure has been determined by single-crystal X-ray diffraction methods. The structure consists of a heavy atom triangle consisting of one Se and two Fe atoms. The Fe-Fe and the two Fe-Se edges are bridged by methylene groups.     

Boron and nitrogen-codoped TiO2 nanorods: Synthesis, characterization, and photoelectrochemical properties

Boron and nitrogen codoped TiO₂ nanorods (BNTRs) were synthesized via two-step hydrothermal reactions using TiN as a starting material. The as-prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscope (SEM), transmission electron microscopy and X-ray photoelectron spectroscopy techniques. The results showed that TiO₂ nanorods with the diameter of approximately 50–100 nm and the length of several micrometers were doped by the interstitial N and B. The nanorods were firstly formed in the hydrothermal synthesis of nitrogen doped TiO₂. The growing process of nanorods was observed by SEM and a most probable formation mechanism of the trititanate nanorods was proposed. The BNTRs showed a higher photocatalytic activity and a bigger photocurrent response than N–TiO₂ nanorods under visible light irradiation.     

Synthesis, characterization, and electronic structure of diimine complexes of chromium

We have prepared and structurally characterized several complexes of chromium coordinated by diimine (or 1,4-diazadiene) ligands, that is, Ar-N=C(R)-(R)C=N-Ar (RL(Ar)) (where Ar = 2,6-diisopropylphenyl ("iPr") or 2,6-dimethylphenyl ("Me") and R = H or Me). The reaction of CrCl2 with HLiPr gave dinuclear [(HLiPr)Cr]2(mu-Cl)3(Cl)(THF) when isolated from Et2O; in THF solution, however, the product exists as mononuclear (HLiPr)CrCl2(THF)2. Two isostructural derivatives, (MeLMe)CrCl2(THF)2 and (HL(Me))CrCl2(THF)2, have also been prepared. Furthermore, the bis-ligand complex, (HLiPr)2Cr, has been prepared along with its reduction product, Li(THF)4[(HLiPr)2Cr]. We have also synthesized the tetracarbonyl complex, (HLiPr)Cr(CO)4, by addition of HLiPr to Cr(CO)4(NCCH3)2. The structure and variable temperature magnetic susceptibility of the previously reported Cr halide dimer, [(HLiPr)Cr(mu-Cl)]2, is also discussed in detail. All of the diimine complexes have been characterized structurally, spectroscopically, and magnetically, and their electronic structures are discussed with the aid of density-functional theory calculations.     

Synthesis, growth, structure and characterization of a new semiorganic crystal

A new semiorganic single crystal, tris(allylthiourea)silver(I) nitrate was grown from an aqueous solution containing silver(I) nitrate and allylthiourea by slow evaporation solution growth technique at room temperature. The crystal belongs to trigonal system with centrosymmetric space group R3 and the cell parameters are, a = 12.5090(4) Å, b = 12.5090(4) Å, c = 21.7130(8) Å, V = 3348.89 Å³, and Z = 6. The various functional groups present in the molecule are confirmed by Fourier transformed infrared spectroscopy. High transmittance is observed in the visible region and band-gap energy is calculated by Kubelka–Munk algorithm. The structure and the crystallinity of the materials were further confirmed using powder X-ray diffraction analysis. Microhardness studies were also carried out to elucidate the mechanical behavior. Thermogravimetric and differential thermal analysis reveal the purity of the sample and no decomposition is observed up to the melting point.