Discotic metallomesogens: Synthesis and properties of square planar metal bis(β-diketonate) complexes

Discotic β-diketonate liquid crystals containing palladium(II), and oxovanadium(IV), (V≡0), analogous to known copper complexes (which display discotic lamellar and columnar mesophases), have been prepared and characterized. These are the first enantiotropic discotics containing Pd(II) and among the earliest examples containing VO(IV). The best-behaved Pd(II) complex is [Pd(DK 10, 10)₂], and it also is probable that the complexes [Pd(DKn,n)₂] (n = 7-9) are mesomorphic, however their characterization is difficult due to decomposition in the isotropic phase. The mesophase of [Pd(DK 10²,10²)₂], which appears below 100°C, is suggested to be an example of the rare N_d phase on the basis of optical microscopy. The complex [VO(DK8,8)₂] is an enantiotropic discotic vanadyl complex; the monotropic behaviour of [VO(DK 10,10)₂] was also confirmed. It is suggested that the discotic phase which occurs for [VO(DK 8,8)₂] is more organized than that of [Cu(DK 8,8)₂].     

Synthesis, reaction and structure of a series of chromium(III) complexes containing oxalate ligand

A series of chromium(III) complexes [Cr(bipy)(HC₂O₄)₂]Cl·3H₂O (1), [Cr(phen)(HC₂O₄)₂]Cl·3H₂O (2), [Cr(phen)₂(C₂O₄)]ClO₄ (3), [Cr₂(bipy)₄(C₂O₄)](SO₄)·(bipy)_0.5·H₂O (4) and [Mn(phen)₂(H₂O)₂]₂[Cr(phen)(C₂O₄)₂]₃ClO₄·14H₂O (5) were synthesized (bipy=4,4′-bipyridine, phen=1,10-phenanthroline), while the crystal structures of 1 and 3–5 have been determined by X-ray analysis. 1 and 3 are mononuclear complexes, 4 contains binuclear chromium(III) ions and 5 is a 3D supromolecule formed by complicated hydrogen bonding. 1–3 are potential molecular bricks of chromium(III) building blocks for synthesis heterometallic complexes. When we use these molecular bricks as ligands to react with other metal salts, unexpected complexes 4 and 5 are isolated in water solution. The synthesis conditions and reaction results are also discussed.     

CuCrO2的合成及其复合催化剂的光催化性能

以硝酸铬和硝酸铜为原料,通过半湿法经两种不同路径合成了CuCrO₂半导体物质。分别采用热重-差示扫描（TG-DSC）、X射线衍射（XRD）、紫外-可见漫反射（UV-vis DR）、扫描电镜（SEM）及X射线光电子能谱（XPS）对样品进行了表征分析。确立了以氨水为Cr³⁺沉淀剂制得的氢氧化铬沉淀中加入硝酸铜溶液是合成CuCrO₂较适宜的路径。借助TG-DSC和XRD的分析结果确立前驱体在热处理的过程中,含Cr物相的变化历程为Cr（OH）₃ → CuCrO₄ → CuCr₂O₄ → CuCrO₂。通过机械研磨的方法合成了CuCrO₂-WO₃和CuCrO₂-ZnO复合型催化剂,对其进行了XRD、SEM和XPS表征分析,并测试了复合催化剂的光催化活性。结果表明,与单独使用CuCrO₂相比,无论是以高压汞灯,还是以氙灯为光源,CuCrO₂-WO₃和CuCrO₂-ZnO的光催化产氢活性都有显著提高。     

Fe Mössbauer spectroscopic studies on M(CO)5(azaferrocene) complexes (M = Cr, Mo, W). The crystal structures of W(CO)5(azaferrocene) and W(CO)5(2,5-dimethylazaferrocene)

⁵⁷Fe Mössbauer spectroscopic studies on M(CO)₅(azaferrocene) complexes (M = Cr, Mo, W) as well as the crystal structures of W(CO)₅(azaferrocene) and W(CO)₅(2,5-dimethylazaferrocene) are reported. The complexation of azaferrocene to the M(CO)₅ moiety brings about only a small change in the quadrupole splitting. The structures of both tungsten complexes reveal a significant shortening of the W-C bonds trans to the nitrogen. These data indicate that azaferrocene behaves as a relatively strong σ-donor and there is no evidence for any π-acceptor properties.     

含侧链盘状苯并菲和棒状偶氮苯的二嵌段液晶共聚物的可控合成及其光物理性质

分别通过可逆加成-断裂链转移（RAFT）聚合和原子转移自由基聚合（ATRP）结合叠氮-端炔基大分子点击反应,制备了一系列不同聚合度和不同嵌段比例的基于侧链苯并菲TP盘状液晶基元和偶氮苯Azo棒状液晶基元的盘棒杂化二嵌段共聚物。采用核磁共振氢谱（¹H NMR）、凝胶渗透色谱（GPC）、差示扫描量热分析（DSC）和正交偏光分析（POM）对盘棒杂化二嵌段共聚物的组成结构、相对分子质量和液晶相行为进行了表征。偶氮苯嵌段较短的共聚物P（TP₆）₄₀-b-P（Azo）₁₀,主要表现出占优势嵌段TP盘状液晶聚合物的热转变温度与相行为。而偶氮苯嵌段较长的共聚物P（TP₆）₁₀-b-P（Azo）₄₀和P（TP₆）₄₀-b-P（Azo）₄₀则更多体现出类似Azo棒状侧链液晶聚合物的相行为和光响应特性。小角/广角X射线散射（SAXS/WAXS）分析证实了Azo嵌段较长的嵌段共聚物薄膜尤其经退火处理后呈现层状结构,倾向于平行基底取向排布的苯并菲诱导偶氮苯平躺沿着平行基底方向排列而显著减少了光吸收,经紫外及可见光的辐照后光吸收显著增大,其中盘状嵌段较长的P（TP₆）₄₀-b-P（Azo）₄₀对比响应增幅尤其明显。这种盘棒杂化二嵌段共聚物薄膜所表现出的特殊光物理性质及其快速光响应-回复特性,加深了对其相互作用的理解,可望为设计合成新的光响应材料提供参考依据。     

Strukturen und reaktionen von methylantimondihalogeniden und versuche zur darstellung von methylantimon

MeSbCl₂ (1) and SbCl₃ give the adduct MeSbCl₂·0.6SbCl₃ (1a). MeSbBr₂ (2) reacts with NaI to form MeSbI₂ (3) and with Cr(CO)₅ THF to give Me(Br)₂SbCr(CO)₅ (4). The crystal structures of 1a, 2 and 4 are reported. Derivatives of methyl antimony are obtained by reaction of 2 or 4 with Mg in tetrahydrofuran.     

Preparation and structure of (η-cyclopentadienyl)(η-tetraphenylcyclobutadiene) cobalt coordinated by four Cr(CO)3 units at the phenyl rings

The reaction of (η⁵-cyclopentadienyl)(η⁴-tetraphenylcyclobutadiene)cobalt (1) with excess Cr(CO)₆ yielded several heterometallic compounds: 2, 3 (3′ and 3″), 4 and 5 with, respectively, one, two, three and four phenyl rings complexed with Cr(CO)₃ fragment(s). These compounds were characterized by mass, infrared, ¹H and ¹³C NMR spectra. The crystal structure of 5 was determined. In 5 the four Cr(CO)₃ fragments are on the same side of the CpCo fragment; whereas, the two Cr(CO)₃ fragments of 3′, the precursor of 5, are pointed in a different direction from the CpCo fragment. The cyclopentadienyl ring shows a static disorder around the axis that passes through the cobalt and the centre of the ring.     

Evidence from x-ray photoelectron spectroscopy on the charge distribution in various chromium compounds

Measurements of various core-level binding energies in the compounds K₃CrF₆, K₃Cr(CN)₆ and Cr(acac)₃ are reported. The binding energies of the L_III level of Cr in these compounds, and in Cr(CO)₆ and K₂CrO₄, are analyzed to yield charge differences between the chromium atom in Cr(acac)₃ and in the other compounds.     

Chemie polyfunktioneller moleküle : LXXXVII. Synthese und reaktionsverhalten von 4-methyl-1,2,6-tristiba-tricyclo[2.2.1.0]heptan (Sb3-nortricyclan) gegenüber chrom-, molybdän- und wolframhexacarbonyl

The reaction of CH₃C(CH₂Cl)₃ and NaSb(C₆H₅)₂ in liquid ammonia leads to Sb₂(C₆H₅)₄ (I). Using CH₃C(CH₂Br)₃ instead of CH₃C(CH₂Cl)₃ results in the formation of I and CH₃C[CH₂Sb(C₆H₅)₂]₃ (II). Treatment of II with gaseous HCl in dry CH₂Cl₂ yields CH₃C(CH₂SbCl₂)₃ (III) under elimination of benzene. The reduction of III with Na in THF gives the first all-cis-organocyclotristibane (Sb₃-nortricyclane) CH₃C(CH₂Sb)₃ (IV) which forms the new CH₃C(CH₂Sb)₃M(CO)₅ complexes (Va---Vc) with M(CO)₅THF (M = Cr, Mo, W).     

Light scattering from a nematic monodomain in an electric field Twist elastic constant and viscosity coefficient of nematic polymer-solvent mixtures

The light scattering technique was used to investigate the viscoelastic parameters characterizing director twist distortions in miscible nematic mixtures of 5CB (pentacyanobiphenyl) with two side chain liquid crystal polymers and a main chain liquid crystal polymer. By applying an AC electric field to homeotropically-aligned nematic monodomains of the mixtures, the field-dependent scattering intensities and director orientation fluctuation relaxation rates yield, respectively, the twist elastic constant K₂₂ and viscosity coefficient γ₁. The results directly demonstrate that the addition of liquid crystal polymers causes substantial decreases of the relaxation rates for dynamic light scattering from the twist mode and these changes are due to small decreases in K₂₂ coupled with large increases in γ₁. The decrements in K₂₂ are comparable for both side chain and main chain liquid crystal polymers. The relative increase in the twist viscosity for the side chain liquid crystal polymers is much smaller than those of main chain polymers. A theoretical model is used to qualitatively interpret the difference between the viscous behaviour of the twist mode for both side chain and main chain liquid crystal polymers in a nematic solvent.     

Synthesis and crystal structure of a germanium(II) calix[6]arene containing unusual diamidosilyl ether groups

The reaction of Ge[N(SiMe₃)₂]₂ with calix[6]arene furnishes a novel macrocyclic product having two divalent germanium atoms incorporated into a Ge₂NO rhombus which contains a μ₂-oxygen atom and a μ₂-NH₂ group. The crystal structure of the product indicates the presence of a conformationally rigid molecule where three of the six oxygen atoms of the calix[6]arene are bound to the germanium atoms while the remaining three have been converted into –OSiMe₃ or unusual –OSi(H)(NH₂)₂ groups. Spectral (¹H, ¹³C, and ²⁹Si NMR) data in solution are consistent with the solid-state structure and indicate the germanium calix[6]arene retains its structure in solution.     

New heterodimetallic cyclopentadienyl carbonyl complexes: crystal structure of (C5Me4Et)(μ-CO)3Ru(C5Me5)

A series of heterodimetallic complexes of general formula (C₅R₅)M(μ-CO)₃RuC₅Me₅ (M = Cr, Mo, W; R = Me, Et) has been prepared in good yields by the reaction of [C₅R₅M(CO)₃]⁻ with [C₅Me₅Ru(CH₃CN)₃]⁺. (C₅Me₄Et)W(μ-CO)₃Ru(C₅Me₅) was characterized by a crystal structure determination. The W---Ru bond length of 2.41 Å is consistent with the formulation of a metal-metal triple bond, while the unsymmetrical bonding mode of the three bridging carbonyl groups reflects the inherent non-equivalence of the two different C₅R₅M-units. Using [CpRu(CH₃CN)₃]⁺ or [CpRu(CO)₂(CH₃CN)]⁺ as the cationic precursor leads to the formation of dimetallic species (C₅R₅)M(CO)₅RuC₅H₅ with both bridging and terminal carbonyl groups.     

Discotic Liquid Crystals of Transition Metal Complexes VI. Monotropic Lamella Mesomorphism of Tetrakis(N-Alkyldithiolato)Dinickel(II) and Bis(N-Alkylxanthato)Nickel(II) Complexes

It was found that each of the tetrakis(n-alkyldithiolato)dinickel(II), (C_n-DTA)₄-Ni₂, complexes where n-alkyl is n-pentyl through n-dodecyl, exhibits a broken-fan texture on cooling from an isotropic liquid, and that the phase gave a characteristic lamella structure X-ray diffraction powder pattern. Furthermore, the infrared spectrum of this phase is more similar to that of the isotropic liquid than that of the crystal. Therefore, the phase can be described as a monotropic lamella mesophase. Interestingly, each of the complexes of bis(n-alkylxanthato)nickel(II), (C_n-Xan)₂Ni, (n = 5, 7, 9, 11) exhibits double (triple) melting behavior via the isotropic liquid, whereas each of the complexes of (C_n-Xan)₂Ni (n = 4, 6, 8, 10, 12) shows ordinary single melting behavior. Such unique double melting accompanied by an even-odd effect appears to be the first example of this in the long chain substituted compounds. Each of the complexes of (C_n-Xan)₂ Ni (n = 9, 11, 12) has a monotropic lamella mesophase exhibiting a large broken fan texture.     

Infrared matrix isolation study of the reaction of CrCl2O2 with (CH3)2O and (CH3)2CO

Matrix isolation has been combined with infrared spectroscopy to study the reaction chemistry of CrCl₂O₂ with (CH₃)₂O and (CH₃)₂CO. Very similar results were obtained with twin jet and room temperature merged jet deposition, indicating that the initial product forms on the surface of the matrix during deposition, not in the deposition lines prior to matrix condensation. The initial product in both systems was identified as the 1:1 complex between the two reagents, with a structure in which the oxygen atom of the base donates electron density to the Cr center. A number of perturbed vibrational modes of both subunits were observed; for the bases, these modes were vibrations involving the oxygen atom. Hg arc irradiation of the CrCl₂O₂·O(CH₃)₂ complex led to growth of a secondary product that is tentatively identified as Cl₂CrO(OCH₃)₂. The CrCl₂O₂·OC(CH₃)₂ complex was not photosensitive, and no rearrangements were observed.     

Reaktionen an komplexgebundenen liganden : XIV. Basenkatalysierter H—D-austausch und disproportionierung von komplexgebundenem diimin in μ-N2H2[Cr(CO)52; modellreaktionen der enzymatischen N2-fixierung

Complexed diimine in μ-N₂H₂[Cr(CO)₅]₂ undergoes a rapid H — D-exchange with deuterium ions, which is inhibited completely by acids; the rate of the H — D exchange is significantly larger for the diimine complex that for the corresponding hydrazine and ammonia complexes, which is explained by the acidic properties of the diimine protons. In the presence of catalytic amounts of strong base N₂H₂[Cr(CO)₅]₂ disproportionates fast and irreversibly to N₂[Cr(CO)₅]₂ and N₂H₄[Cr(CO)₅]₂; a mechanism is proposed for this reaction. The reactions of the complexed diimine are compared to those of the free diimine; their significance with respect to intermediated steps of the enzymatic N₂ fixation is discussed.     

Sterically demanding cyclopentadienyl chemistry: synthesis of iron and zirconium complexes of 1-phenyl-3-methyl-4,5,6,7-tetrahydroindenyl

Reaction of phenyl magnesium bromide with the ,β-unsaturated ketone 3-methyl-2,3,4,5,6,7-hexahydroind-8(9)-en-1-one, followed by an aqueous work-up, generates the pro-chiral tetra-substituted cyclopentadiene, 1-phenyl-3-methyl-4,5,6,7-tetrahydroindene, Cp^‡H, a precursor to the η⁵-cyclopentadienyl ligand in (Cp^‡)₂Fe and [(Cp^‡)Fe(CO)]₂(μ-CO)₂. Both complexes were generated as mixtures of rac-(RR and SS)- and meso-(RS)-isomers, and in either case pure meso-isomer was isolated by crystallisation and characterised by single crystal X-ray structure, both molecules having crystallographic C_i symmetry. Reduction with Na/Hg cleaves meso-(RS)-[(Cp^‡)Fe(CO)]₂(μ-CO)₂ and the resulting mixture of (R)- and (S)-[(Cp^‡)Fe(CO)₂]⁻ anions reacts with MeI to give racemic (Cp^‡)Fe(CO)₂Me, which was characterised by the X-ray crystal structure. The Cp^‡ ligand is more electron donating than (η-C₅H₅) as revealed by the reduction potential of the (Cp^‡)₂Fe⁺/(Cp^‡)₂Fe couple, E°=−0.127 V (vs. Ag  AgCl). Reaction of LiCp^‡ with ZrCl₄ yields the zirconocene dichloride [Zr(Cp^‡)₂Cl₂] as mixture of rac- and meso-isomers, from which pure rac-isomer is obtained as a mixture of RR and SS crystals by recrystallisation. The reaction of rac-[Zr(Cp^‡)₂Cl₂] with LiMe gives rac-[Zr(Cp^‡)₂Me₂]. The structures of RR-[Zr(Cp^‡)₂Cl₂] and rac-[Zr(Cp^‡)₂Me₂] have been determined by X-ray diffraction. The structural studies reveal the influence of the bulky substituted cyclopentadienyl ligand on the metal---Cp^‡ distances and other metric parameters.     

Synthesis and Characterization of [Cu(N-MeIm)4(BF4)2] in Ionic Liquid

A new transition metal complex, [Cu(N-MeIm)₄(BF₄)₂](N-MeIm=N-methylated imidazoles, BF₄= tetrafluoroborate), was synthesized via the solvothermal method in ionic liquid. The ionic liquid acts as thermal decomposition reaction medium, soft temple agent and ligand compound. The central Cu(II) ion is coordinated by four N atoms from four N-methylated imidazole ligands, and the four N-methylated imidazole rings are perpendicular to each other. The crystal structure of [Cu(N-MeIm)₄(BF₄)₂] was determined by single crystal X-ray diffraction. The results of thermogravimetry(TG) and Fourier transform infrared spectrometry(FTIR) analyses were in accordance with that of crystal structure. The complex showed strong ligand-based absorbance with maximum wavelength at 208 and 231 nm, which are attributed to π-π^* transition of the N-methylated imidazole ligands.     

高氯酸二甘氨酸十二水合二铒的晶体结构

在水溶液中合成了甘氨酸铒配合物[Er₂(Gly)₂(H₂O)₁₂](ClO₄)₆·4H₂O单晶,并测定了其晶体结构。该晶体属单斜晶系,P2₁/n空间群。晶胞参数:a=1.0571(2)nm,b=1.0837(2)nm,c=1.7728(4)nm,β=90.09(3)°,V=2.0309(7)nm²,Z=2,D_c=2.239g/cm³.最终偏差因子R=0.055,R_w=0.061.每2个Er³⁺离子由2个甘氨酸羧基桥联成双核结构。Er³⁺离子还与6个水分子的氢原子配位,形成畸变的四方棱柱型配位多面体。     

A Novel Dimer--Heteropolytungstate with a Vanadium Atom as the Centre--Synthesis and Structural Characterization of (H3O)4[VW12O40Na(H2O)4]2

A novel dimer-tungstovanadate,(H3O)4［VW12O40Na(H2O)4］2,was hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction,IR spectra,TGA-DSC thermal analysis and polarograpy.The yellowish crystal crystallized in the triclinic system,space group ,a=1.464 5(3) nm,b=1.4686(3) nm,c=1.4111(3) nm,α=111.82(2)°,βA novel dimer-tungstovanadate,(H3O)4［VW12O40Na(H2O)4］2,was hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction,IR spectra,TGA-DSC thermal analysis and polarograpy.The yellowish crystal crystallized in the triclinic system,space group ,a=1.464 5(3) nm,b=1.4686(3) nm,c=1.4111(3) nm,α=111.82(2)°,β=93.17(3)°,γ=117.47(3)°,V=2.2106(8) nm3,Z=1,Dc=4.552 g.cm-3,λ(Mo Kα)=0.071073 nm,μ=31.402 mm-1,F(000)=2648,R=0.0780.The title compound consists of two Keggin structure units linked together with two hydrated sodium cations to form a dimer with a porous structure with the pore dimension of 0.766 nm×0.7785 nm.     

高碳铬铁在氢氧化钠水溶液中电化学氧化过程

铬铁电化学氧化法是一种新的制备铬酸钠的方法,然而高碳铬铁在NaOH水溶液中的电化学氧化过程尚不明确。 采用循环伏安法(CV)、稳态极化法(LSV)等电化学测试方法对金属铬、高碳铬铁在NaOH水溶液中的电化学氧化过程进行研究,通过扫描电子显微镜(SEM)、能量散射谱(EDS)和X射线光电子能谱(XPS)对高碳铬铁电解后固相产物表征,判断固相产物的组成。 结果表明,高碳铬铁不同于金属铬的电氧化过程,它在NaOH溶液中通过Cr(0)→Cr(Ⅵ)的电氧化方式生成铬酸钠,中间产物Cr(OH)₃和Fe(0)发生电化学反应生成稳定的FeCr₂O₄。 随着NaOH浓度的增加,电势较低时,受高碳铬铁中Fe(0)的影响,高碳铬铁容易在NaOH水溶液中发生钝化;当电势足够正时,钝化膜溶解,生成铬酸钠、氢氧化铁和亚铬酸亚铁,同时,阳极表面有氧气析出。 高碳铬铁电化学氧化制备铬酸钠的适宜条件:碱浓度≥2 mol/L,阳极电势≥1.6 V(vs.SCE)。