一种基于Lindqvist型多酸阴离子的三维多金属铌酸盐的晶体结构(英文)

利用扩散法合成了K_3 NaH_1Nb_6O_(19)·11H_2O(1),借助IR、UV和X射线单晶衍射分析对这种化合物进行了结构和性质研究.其晶胞参数为:a=1.812 8(6)nm,b=1.790 8(6)nm,c=1.8130(7)nm,V=5.886(4)nm~3,Z=8,R_1[I>2σ(I)]=0.071 0,ωR_2[I>2σ(I)]=0.1857.化合物1由一个Lindqvist型[H_4Nb_6O_(19)]~1聚阴离子,三个K~4离子,一个Na~+离子和十一个H_2O组成.     

Reactivity studies of oxo-Mo(IV) complexes containing potential hydrogen-bond acceptor/donor phenolate ligands

Reactivity studies of oxo-Mo(IV) complexes, Tp(iPr)MoO{2-OC(6)H(4)C(O)R-κ(2)O,O'} (R = Me, Et, OMe, OEt, OPh, NHPh), containing chelated hydrogen-bond donor/acceptor phenolate ligands are reported. Hydrolysis/oxidation of Tp(iPr)MoO(2-OC(6)H(4)CO(2)Ph-κ(2)O,O') in the presence of methanol yields tetranuclear [Tp(iPr)MoO(μ-O)(2)MoO](2)(μ-OMe)(2) (1), while condensation of Tp(iPr)MoO{2-OC(6)H(4)C(O)Me-κ(2)O,O'} and methylamine gives the chelated iminophenolate complex, Tp(iPr)MoO{2-OC(6)H(4)C(Me)NMe-κ(2)O,N} (2), rather than the aqua complex, Tp(iPr)MoO{2-OC(6)H(4)C(Me)NMe-κO}(OH(2)). The oxo-Mo(IV) complexes are readily oxidized by dioxygen or hydrogen peroxide to the corresponding cis-dioxo-Mo(VI) complexes, Tp(iPr)MoO(2){2-OC(6)H(4)C(O)R}; in addition, suitable one-electron oxidants, e.g., [FeCp(2)]BF(4) and [N(C(6)H(4)Br)(3)][SbCl(6)], oxidize the complexes to their EPR-active (g(iso) ≈ 1.942) molybdenyl counterparts (3, 4). Molybdenyl complexes such as Tp(iPr)MoOCl{2-OC(6)H(4)C(O)R} (5) and Tp(iPr)MoOCl(2) also form when the complexes react with chlorinated solvents. The ester derivatives (R = OMe, OEt, OPh) react with propylene sulfide to form cis-oxosulfido-Mo(VI) complexes, Tp(iPr)MoOS{2-OC(6)H(4)C(O)R}, that crystallize as dimeric μ-disulfido-Mo(V) species, [Tp(iPr)MoO{2-OC(6)H(4)C(O)R}](2)(μ-S(2)) (6-8). The crystal structures of [Tp(iPr)MoO(μ-O)(2)MoO](2)(μ-OMe)(2), Tp(iPr)MoO{2-OC(6)H(4)C(Me)NMe}, Tp(iPr)MoOCl{2-OC(6)H(4)C(O)NHPh}·{2-HOC(6)H(4)C(O)NHPh}, and [Tp(iPr)MoO{2-OC(6)H(4)C(O)R}](2)(μ-S(2)) (R = OMe, OEt) are reported.     

Selective hydroformylation of various olefins using diphosphinite ligands

Novel diphosphinite ligands are synthesized by the reaction of various derivatives of 1,3‐diols with chlorodiphenylphosphine. The synthesized ligands exhibited considerable impact on hydroformylation of various olefins with excellent regioselectivity toward branched aldehyde. The effect of solvent, temperature, pressure and catalyst loading on the hydroformylation reaction is also described. The synthesized diphosphinite ligands with rhodium precursor works under milder reaction conditions as compared to traditional phosphine and phosphite‐based ligands. Copyright © 2013 John Wiley & Sons, Ltd.     

The effect of an intermetallic hydrogen acceptor on catalytic aromatization of propane

The effect of the intermetallic compound Zr₂Fe as a hydrogen acceptor in the aromatization of propane in the presence of a zeolite catalyst has been investigated. High-silica, pentasil-type zeolite ZVM was modified by Zn, Ga, or Pt. The intermetallic compound was found to remove hydrogen formed during aromatization, resulting in a 2-to 5-fold increase in the yields of aromatics and in a marked increase in selectivity for aromatization. The magnitude of this effect is shown to be dependent on the catalyst composition.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 61–63, January, 1993.     

Effects of various donor: acceptor blend ratios on photophysical properties in non-fullerene organic bulk heterojunctions

In this work, the donor:acceptor ratio effected photophysical properties of non-fullerene organic solar cells are comparatively investigated. Effective transportation of the photo-generated charge carriers can be obtained with the PDBD-T:ITIC ratio variation. There is no significant energy loss variation exists in the process of changing the D:A ratio.     

Magnetic interaction between iron/III/ ions in its complexes of some sugar type ligands

Mössbauer and temperature dependent EPR spectra of three iron/III/ complexes, formed with sugar type ligands /galactose, sorbitol and 1,2-propylene glycol/ were investigated. Measurements showed antiferromagnetic interaction between the iron/III/ central atoms in the specimens. On the basis of the EPR data the temperature dependence of partial susceptibilities of isolated and interacting iron/III/ centres could be determined.     

Simple Michael acceptor type coumarin derived turn-on fluorescence probes to detect cyanide in pure water

The present article describes design and synthesis of coumarin derived chemical reaction based chemodosimeter to recognize cyanide in aqueous medium. The Michael acceptor type coumarin derived probes 3 and 4 upon interaction with cyanide undergo Michael type nucleophilic addition reaction to form adducts in which fluorescence intensity was significantly enhanced, ‘turn-on’ by the change in intramolecular charge transfer (ICT) mechanism. The nonfluorescent color of solutions changed to a naked-eye sensitive fluorescent blue (switched-on). Job’s plot analysis revealed a 1:1 stoichiometry for the interaction between the probe and cyanide anion with a high detection limit.     

Tetrathiafulvalene hydrazone an efficient precursor of various chelating electroactive ligands

Novel bidentate electroactive ligands containing one or two tetrathiafulvalene (TTF) cores as redox active unit have been synthesized thanks to the condensation of various carbonyl derivatives with TTF hydrazone. The electron donating ability of these redox active ligands determined by cyclic voltammetry is described together with the investigations of their molecular structures by X-ray diffraction studies. The chelating ability of these ligands has been exemplified through the coordination to molybdenum carbonyl fragment or the complexation to difluoroboron moiety.     

Bis(cyclopentadienyl) compounds of zirconium with various ligands

Russian Chemical Bulletin -     

Metal-free N-h insertions of donor/acceptor carbenes

Synthetically useful transformations arise from the thermal decomposition of aryldiazoacetates in the presence of primary and secondary amines without the use of a metal catalyst. Thermally generated, free donor/acceptor carbenes directly undergo N-H insertion with amines through selective aza-ylide formation to afford a variety of α-amino esters in 53-96% yields.     

Synthesis and characterization of original calix-salen type ligands

Polycondensation reactions between various modified disalicylaldehyde derivatives and two chiral diamines afforded in each case macrocyclic structures, named calix-salen. Mixtures of oligomers (dimers to pentamers) were qualitatively analyzed by Maldi-Tof and ¹H NMR DOSY experiments allowed their easy quantitative investigation. Tuning the reaction conditions and namely the concentration of both monomeric partners led interestingly to the selective preparation of the dimer or the tetramer as main products, in diluted or concentrated media, respectively.     

The effect of hydrogen bond acceptor properties of ionic liquids on their cellulose solubility

It is nowadays well-known that ionic liquids can dissolve cellulose. However, little systematic data has been published that shed light onto the influence of the ionic liquid structure on the dissolution of cellulose. We have conducted 1H NMR spectroscopy of ethanol in a large number of ionic liquids, and found an excellent correlation of the data obtained with the hydrogen acceptor properties (β-values). With this tool in hand, it is possible to distinguish between cellulose-dissolving and non-dissolving ionic liquids. A modulating effect of both, the anion of the non-dissolving ionic liquid and its cation was found in solubility studies with binary ionic liquid mixtures. The study was extended to other non-dissolving liquids, namely water and dimethylsulfoxide, and the effect of the cation was also investigated.     

The effect of organic nitrogenous compound content and different pretreatments on agricultural lignocellulosic biomass characterization methods

Considering the diverse compounds contained in lignocellulosic biomasses, especially in agricultural biomass, and the complexity of the different chemical and physical structural connections between these compounds, appropriate analytical methods must be used to characterize these biomasses. In this study, two extraction processes and two analytical methods were used to characterize the main compounds in corn stover residue before and after different pretreatments. The results of this study suggest that pretreatment and organic nitrogenous compound content greatly affect the most common extraction processes and analytical methods used for biomass characterization. For raw corn stover biomass residue, the extraction process using neutral detergent fiber solvent removed more extractives and more organic nitrogenous compounds (18.5 and 2.4%, respectively) than the combination of extractions using water and ethanol (13.4% of extractives and 1.8% of organic nitrogenous compounds). This study also showed that the different pretreatments improve the efficiency of both extraction processes and that these processes seem to be more effective with the neutral detergent solvent extraction than the combination of extractions with water and ethanol. Organic nitrogenous compounds represent a significant proportion of agricultural biomasses; therefore, insufficient organic nitrogenous compound extraction can cause interference with different characterization methods. It was observed that, for the same analytical method and with the raw biomass, the value of insoluble lignin after the extractions with water and ethanol was higher than that obtained after the extraction with the neutral detergent solvent 16.1 and 13.2%, respectively. This can be explained by the fact that there are more organic nitrogenous compounds in the samples after the extraction with water and ethanol than in the samples after the extraction with the neutral detergent solvent. This result was also observed for the pretreated samples. These results, therefore, show that the extraction step is very important because it can remove more organic nitrogenous compounds before the main compounds are characterized (lignin, carbohydrates).     

The effect of peripheral bipyridine ligands on the photocatalytic hydrogen production activity of Ru/Pd catalysts

A pyrazine bridged ruthenium/palladium bimetallic photocatalyst with peripheral 4,4'-dicarboxyethyl-2,2'-bipyridine ligands, EtOOC-RuPd, is reported, together with its 2,2'-bipyridine analogue. Upon irradiation with visible light, EtOOC-RuPd catalyses the production of hydrogen gas whereas the complex RuPd does not.     

Synthesis of new polydentate tweezers ligands of amido-amine type

A series of new tweezers amido-amine ligands containing pyrrole, bipyrrole, and dipyrrolylmethane fragments were synthesized by reaction of 2-thioxothiazolidin-3-yl derivatives of α-pyrrolecarboxylic acids {5-[1-(5-carboxy-3-methyl-4-phenyl-1H-pyrrol-2-yl)-1-methylethyl]-4-methyl-3-phenyl-1H-pyrrole-2-carboxylic acid, 5-[(5-carboxy-3-methyl-4-phenyl-1H-pyrrol-2-yl)phenylmethyl]-4-methyl-3-phenyl-1H-pyrrole-2-carboxylic acid, 5-(5-carboxy-3-methyl-4-phenyl-1H-pyrrol-2-yl)-4-methyl-3-phenyl-1H-pyrrole-2-carboxylic acid, and 3,4-dimethyl-pyrrole-2,5-dicarboxylic acid} with o-phenylenediamine. All compounds obtained were characterized by elemental analysis, NMR and mass spectra.