Synthesis and characterization of organophosphoryl polyoxotungstates [RP(O)]2X n+W11O39 (8−n)− (X n+ = P5+, Si4+, Ge4+, Ga3+)

In the presence of n-Bu₄NBr acting as phase-transfer reagent, n-Bu₄N⁺ salts of organophosphoryl polyoxotungstate derivatives [RP(O)]₂X ⁿ⁺W₁₁O₃₉ ^(8–n)– [R = PhCH₂CH₂P(O), X = P, Si; R = C₆H₁₁P(O); X = Ge, Ga] have been prepared and characterized by elemental analysis, i.r., ³¹P- and ¹⁸³W-n.m.r. spectroscopy. According to the elemental analysis and spectroscopic data, the hybrid anions consist of an -[XW₁₁O₃₉] framework on which are grafted two equivalent organophosphoryl groups through P—O—W bridges; these new species still retain the Keggin structure. The six-line ¹⁸³W spectrum indicates that hybrid anions possess C _s symmetry in MeCN.     

Étude structurale comparée des chromates: M(I)M(III)(CrO4)2; M(I) = Li+, Na+, K+, Rb+, Cs+, NH4+, Ag+ et Tl+; M(III) = Al3+, Fe3+, Cr3+, Tl3+ et Bi3+

Among compounds of formula type M(I)M(III)(CrO₄)₂, the structures of trivalent bismuth compounds are always different from the others, because the surrounding of bismuth is never well-defined. Besides, nearly all these compounds have two-dimensional structures with the exception of Tl(I)Tl(III)(CrO₄)₂ which is three-dimensional. This structural type can exist only when the ionic radius of the monovalent cation has a value near that of O²⁻ ion (1.40 Å), as for Rb⁺, NH₄⁺ and Tl⁺.     

一缺位杂多阴离子XW11O(12-n)-39(X=P5+,Si4+,B3+,Ga3+)含硫有机膦衍生物的合成及结构表征

杂多化合物的衍生物由于具有潜在的多功能催化性能,长期以来一直受到人们的关注[1～3].将有机或有机金属基团引入杂多化合物中以修饰杂多阴离子的部分外部骨架结构,对研究杂多化合物的性质和应用及新型催化剂的开发具有重要意义[4,5].在杂多化合物表面引入适当的有机基团还可改善其溶解性能及其它物理性质,从而拓宽其应用范围.研究结果表明,这类化合物还具有很好的抗病毒和抗肿瘤活性[6,7].Klemperer等[8]合成的[(η5-C5H5)TiPW11O39]4-将多酸与金属有机化合物有机地融为一体,从而开辟了多酸金属有机化学的新领域.此后,相继合成了许多多酸型金属有机化合物[9],然而缺位杂多阴离子的有机膦衍生物的研究却鲜见报道[10].     

TiP2^+,TiP4^+,Ti2P4^+二元团簇的理论研究

利用含有电子相关效应校正的密度泛函理论DFT中的B3LYP方法,选择LANL2DZ双ξ基组,并考虑极化函数,对TiP2^+,TiP4^+,Ti2P4^+二元团簇各种可能存在的几何构型及电子结构进行了密度泛函理论研究,得到了TimPn^+二元团族的最稳定构型,其中TiP2^+的最稳定构型为C2v对称性的三角形,TiP4^+的最稳定构型亦具有C2v对称性,Ti2P4^+的最稳定构型为具有D2d对称性的共边双四面体,所得构型很好地说明了激光光解的实验结果。     

Structures, energetics, and aromaticities of the tetrasilacyclobutadiene dianion and related compounds: (Si4H4)(2-), (Si4H4)(2-)·2Li+, [Si4(SiH3)4](2-)·2Li+, [Si4(SiH3)4](2-)·2Na+, and [Si4(SiH3)4](2-)·2K+

In light of the important recent synthesis of a stable tetrasilacyclobutadiene dianion compound by Sekiguchi and co-workers and the absence of theoretical studies, ab initio methods have been used to investigate this dianion and a number of related species. These theoretical methods predict multiple minima for each compound, and most minima contain folded and bicyclic silicon rings. For (Si(4)H(4))(2-), (Si(4)H(4))(2-)·2Li(+), [Si(4)(SiH(3))(4)](2-)·2Li(+), [Si(4)(SiH(3))(4)](2-)·2Na(+), and [Si(4)(SiH(3))(4)](2-)·2K(+), respectively, the energetically lowest-lying structures are designated A-3 (C(2v) symmetry), B-8 (C(1) symmetry), C-1 (C(2) symmetry), D-1 (C(2) symmetry), and E-1 (C(2h) symmetry). None of these structures satisfies both the ring planarity and the cyclic bond equalization criteria of aromaticity. However, all of the representative NICS values of these lowest-lying structures are negative, indicating some aromatic character. Especially, structures C-1 and D-1 of C(2) symmetry effectively satisfy the criteria of aromaticity due to the slightly trapezoidal silicon rings, which are nearly planar with nearly equal bond lengths. SiH(3) substitution for hydrogen in (Si(4)H(4))(2-)·2Li(+) significantly reduces the degree of aromaticity, as reflected in the substantially smaller NICS absolute values for [Si(4)(SiH(3))(4)](2-)·2Li(+) than those of (Si(4)H(4))(2-) and (Si(4)H(4))(2-)·2Li(+). The aromaticity is further weakened in [Si(4)(SiH(3))(4)](2-)·2Na(+) and [Si(4)(SiH(3))(4)](2-)·2K(+) by replacing lithium with the sodium and potassium cations.     

Crystal structure of salts of the trans-[Rh(NH3)2(NO2)4]− anion with K+, Cs+, Ag+, and (CH3)4N+ cations

Complex rhodium(III) salts with the composition trans-M[Rh(NH₃)₂(NO₂)₄], where M = K⁺, Cs⁺, Ag⁺, and N(CH₃) ₄ ⁺ , are prepared and characterized. The molecular and crystal structures are determined by X-ray crystallography.     

Li~+,Na~+,K~+,Mg~(2+)/Cl~-,SO_4~(2-)-H_2O体系Pitzer热力学模型

介绍了描述25℃Li+,Na+,K+,Mg2+/Cl-,SO42--H2O体系的热力学Pitzer模型.给出了为获得Pitzer混合参数而测定的Li+/Cl-,SO42--H2O,Li+,K+/Cl--H2O,Li+,Na+/Cl--H2O等三元体系和Li+,Mg2+/Cl-,SO42--H2O四离子体系溶液的渗透系数.详细叙述如何利用热力学数据和溶解度数据,获得Li+,Mg2+/Cl-,SO42--H2O,Li+,K+/Cl-,SO42--H2O,Li+,Na+/Cl-,SO42--H2O体系全部混合参数及7种锂盐Gibbs标准生成自由能.进而通过数据对比,介绍了本模型在含Li+多组分溶液25℃热力学性质计算、含Li+多组分体系25℃溶解相平衡预测等方面的应用.     

H+H2体系的态(R)-态(TS)-态(P)理论研究

H+H₂体系的辛准经典轨迹(SQCT)计算表明: 碰撞轨迹分为A, B两种类型, A型是经过过渡态鞍点的, B型是不经过过渡态鞍点的. A型轨迹不全发生反应, B型轨迹却也可发生反应. A, B两种类型轨迹的配分及其反应性, 与反应物初始态(R)有关. 这种轨迹类型A, B影响着产物态(P)(即振转态)分布及其角度分布. 初步建立了化学反应态(R)-态(TS)-态(P)理论研究的雏形, 深化了对Eyring过渡态理论的理解.     

P2(2-) and P(3-) units in the [Rh8P9]δ- polyanion of La4Rh8P9

The phosphide La(4)Rh(8)P(9) was synthesized from the elements in a bismuth flux. The structure was refined from single crystal diffractometer data: space group Cmcm, a = 1303.1(2), b = 1893.2(2), c = 576.70(6) pm, wR2 = 0.0277, 1380 F(2) values, 65 variables. The rhodium and phosphorus atoms build up a three-dimensional [Rh(8)P(9)] polyanion which leaves larger cages for the three crystallographically independent lanthanum sites. The rhodium atoms have between four and six phosphorus neighbors at Rh-P distance ranging from 229 to 254 pm. Three of the four crystallographically independent phosphorus atoms are isolated (P(3-) units), while the P4 atoms form dimers with double bond character (208 pm P-P). The P(2)(2-) diphosphenide units bond side-on to a Rh3 and end-on to four Rh5 atoms. (31)P magic angle spinning (MAS) NMR spectroscopy is able to resolve three of the four crystallographically distinct phosphorus sites. The doubly bonded phosphorus site P4 is characterized by an axially symmetric shielding tensor of moderate anisotropy Δσ = σ(33) - σ(iso) = 257 ppm. Electronic band structure calculations prove the metallic character and reveal the significant difference between the isolated P(3-) and the phosphorus atoms of the P(2)(2-) units. Magnetic susceptibility measurement reveals Pauli paramagnetism.     

Synthesis and Characterization of Li(11)Nd(18)Fe(4)O(39-δ)

Li(11)Nd(18)Fe(4)O(39-δ) has been synthesized by the solid-state reaction of pellets, covered with powder of the same composition to avoid lithium loss, with a final reaction temperature of 950 °C. This phase has been reported previously to have various stoichiometries: Li(5)Nd(4)FeO(10), Li(8)Nd(18)Fe(5)O(39), and Li(1.746)Nd(4.494)FeO(9.493). The crystal structure of Li(11)Nd(18)Fe(4)O(39-δ) is closely related to that reported previously for two of the other three compositions but contains extra Li and differences in Li/Fe site occupancies. Fe is present in a mixture of 3+ and 4+ oxidation states, as confirmed by M?ssbauer spectroscopy. The oxygen content of 39 - δ is variable, depending on the processing conditions. Samples slow-cooled in air from 800 °C are semiconducting, attributed to the presence of Fe(4+) ions, whereas samples quenched from 950 °C in N(2) are insulating.     

Synthesis and mesomorphic properties of 4-(4-bromopropyloxy)-4’-(4-alkyloxybenzylidene)anilines

This article describes the preparation and liquid crystalline properties of a new homologous series of 4-（4-bromopropyloxy）-4’- （4-alkyloxybenzylidene）anilines in which the phenyl ring is armed by a bromopropyloxy chain.The thermal behavior and mesomorphic properties of the synthesized compounds were studied with particular attention given to the correlation between their phase transition temperatures and anisotropic change influenced by molecular structure.All the members displayed enantiotropic smectic phase except for the homologue with the longest alkyloxy chain(R = C₁₈H₃₇),exhibiting only monotropic characteristic. The presence of bromine atom from the propyloxy side chain is found to be capable of altering and influencing the mesomorphic properties.     

[Pt2(P2O5H2)4]4-和[Pt2(P2O4CH4)4]4-基态和激发态性质的理论研究

采用从头计算MP2和CIS方法分别优化等电子双核d8配合物[Pt2(P2O5H2)4]4-和[Pt2(P2O4CH4)4]4-的基态和激发态结构.结果表明基态Pt-Pt距离分别为0.2905和0.2987nm,与实验的0.2925和0.2980nm符合.NBO计算的Pt-Pt键级以及Pt原子间伸缩振动说明Pt-Pt相互作用具有吸引本质.CIS计算揭示电子激发到Pt-Pt的σ(pz)成键轨道使得相互作用增强.保持激发态几何,含时密度泛函理论(TD-DFT)计算的溶液发射分别为449和475nm,与实验值512和510nm接近.     

Ho3+,Yb3+双掺KGd(WO4)2激光晶体的光谱性能

钨酸钆钾是一种新型的激光基质材料.以Yb3 作为Ho3 的敏化剂,采用顶部籽晶提拉法生长出了单斜晶系的HoYbKGW晶体.测试了晶体的红外光谱和拉曼光谱,并对出现的峰值进行了振动归属.分析了晶体的吸收光谱,计算了相应的光谱参数.从荧光光谱可以看出,在1022 nm附近,Yb3 发射主峰的发射线宽达14 nm,对应的是Yb3 的2F5/2和2 F7/2的最低能态之间的跃迁;Ho3 在1985 nm处的荧光发射峰半高宽为45 nm左右,发射截面积为σemp=1.79×10-20cm2.测试了晶体的上转换荧光谱,得到了较强的上转换红光,并分析了相应的上转换机制.     

双掺Er3+,Yb3+离子KY(WO4)2晶体的光谱性质

研究分析了用助熔剂法生长的Er^3 /Yb^3 :KY(WO4)2晶体在室温下的吸收光谱和发射光谱，在吸收谱的350－1750nm区域，除了900－1050nm的谱带是Er^3 ,Yb^3 的共同谱带，其他的都属于Er^3 的谱带，用266nm激发时产生540－560，660－680，850－870，1450－1600nm四个发射带，用976nm激发时产生的主要是Er^3 的1450－1600nm发射带，这两 的能量转移机制不相同。     

4-(4-氨基苯氧基)-2-(烷基氨甲酰基)吡啶的合成

苯氧基胺酰基吡啶兼有芳基吡啶醚结构,因分子中吡啶环的亲脂性、酰胺基团的亲水性及醚键的存在而具有良好的生物活性,是制备抗癌新药索拉非尼[1]、吡啶醚类除草剂[2]等多种医药、农药的重要中间体,该类物质的合成已成为当今化学研究中最活跃和不断扩展的领域之一.     

从(4R)-羟基-(S)-脯氨酸合成4-取代脯氨酸

叙述了以(4R) 羟基 (S) 脯氨酸为原料进行的几种新型手性催化剂的简便合成方法. (4S) 苯氧基 (S) 脯氨酸 1a由N 乙氧羰基 (4R) 羟基 (S) 脯氨酸甲酯经Mitsunobu反应, C 4构型发生翻转, 水解后得到; (4R) 芳甲氧基 (S) 脯氨酸由N 叔丁氧羰基 (4R) 羟基 (S) 脯氨酸用ArCH2X醚化后脱去N 保护基得到, C 4构型不受影响.     

新型1-(4-氨基苯基)-4-(4-甲氧基苯基)哌嗪衍生物的合成

以二乙醇胺为原料,经溴化、环合、N-烷基化和还原4步反应制得关键中间体——4-[4-(4-甲氧基苯基)哌嗪-1-基]苯胺(4);4与酰氯经酰基化反应合成了11个新型的1-(4-氨基苯基)-4-(4-甲氧基苯基)哌嗪衍生物,其结构经1H NMR,FT-IR,ESI-MS和元素分析表征。     

Mesogenic 4-(ω-Hydroxyalkoxy)-4'-formylazobenzenes

Homologs from a series of 4-(-hydroxyalkoxy)-4'-formylbenzenes (C₂,C₃,C₄,C₆ ,C₈) were synthesized. All compounds obtained show properties of thermotropic nematic liquid crystals. The effect of the terminal hydroxy group of the end substituent on the mesomorphous properties of the compounds was analyzed.     

Complexation of 4′-nitrobenzo-15-crown-5 with Li+, Na+, K+, and NH 4 + cations in acetonitrile–methanol binary solutions

The complexation processes between Li⁺, Na⁺, K⁺ and NH ₄ ⁺ cations with macrocyclic ligand, 4′-nitrobenzo-15C5, were studied in acetonitrile–methanol (AN–MeOH) binary mixtures at different temperatures using conductometric method. The conductance data show that the stoichiometry of the complexes formed between the ligand and Li⁺, Na⁺, K⁺ and NH ₄ ⁺ cations is 1:1(M:L). Addition of 4′-nitrobenzo-15C5 to these cations solution, causes a continuous increase in the molar conductivities which indicates that the mobility of the complexed cations is more than the uncomplexed ones. The values of stability constants of the complexes were determined from conductometric data using GENPLOT computer program. The obtained results show that the selectivity order of the ligand for Li⁺, Na⁺, K⁺ and NH ₄ ⁺ cations changes with the nature and composition of the binary mixed solvent. The values of thermodynamic parameters (ΔH°_c, ΔS°_c) for formation of the complexes were obtained from temperature dependence of the stability constants using the van’t Hoff plot. The results show that the complexes are both enthalpy and entropy stabilized. A non-linear behavior was observed between the stability constants (log K _f ) of the complexes and the composition of the AN–MeOH binary solution.