A europium-151 Mössbauer spectral study of Eu(14)MnP(11), Eu(14)MnAs(11), and Eu(14)MnSb(11)

The europium-151 Mossbauer spectra of the Eu(14)MnP(11), Eu(14)MnAs(11), and Eu(14)MnSb(11) Zintl compounds, measured between 4.2 and 100 K, reveal europium(II) for all four crystallographically inequivalent europium sites in Eu(14)MnAs(11) and Eu(14)MnSb(11) and europium(II) and europium(III) for the three 32g and the 16f europium sites in Eu(14)MnP(11), respectively. Below the ordering temperatures of 52, 74, and 92 K, only very small hyperfine fields of 2-4 T are observed at the europium sites as a result of the polarization by the manganese magnetic moments. At 4.2 K, the europium(II) magnetic moments are ordered, and hyperfine fields of 24.4, 24.8, and 19.3 T are observed in Eu(14)MnP(11), Eu(14)MnAs(11), and Eu(14)MnSb(11), respectively, fields that are typical for magnetically ordered europium(II) ions. At 4.2 K the 16f europium(III) sites in Eu(14)MnP(11) experience a transferred hyperfine field of 33 T from the neighboring ordered europium(II) moments. Between its Curie temperature and 4.2 K, the europium-151 Mossbauer spectra of Eu(14)MnSb(11) reveal that the europium(II) moments order below ca. 13 K, i.e., below the second magnetic transition observed in magnetic measurements. Between their Curie temperatures and 4.2 K, the europium-151 Mossbauer spectra of Eu(14)MnP(11) and Eu(14)MnAs(11) are complex and have been analyzed with two models, models that give equivalently good fits. However, the second model in which the spectra are fit with a three-dimensional relaxation of the europium(II) and europium(III) hyperfine fields is preferred for its physical meaning and its reduced number of fitted parameters.     

Structure and stability of the Al14 halides Al14In - (n=1-11): can we regard the Al14 core as an alkaline earthlike superatom?

We have studied the structures and stabilities of Al(14)I(n) (-) (n=1-11) clusters at the density functional level of theory. The experimentally observed Al(14)I(n) (-) (n=3, 5, 7, 9, and 11) [Bergeron et al., Science 307, 231 (2005)] are found to be stable both kinetically and thermodynamically. Al(14)I(3) (-), not Al(14)I(-), is the first member of the Al(14)I(n) (-) series in the mass spectrometric experiment, which is ascribable to the low kinetic stability of the Al(14)I(-) cluster. The Al(14) core in Al(14)I(3) (-) is close to neutral Al(14), both electronically and structurally. Population analysis shows that charge transfer occurs from the Al cluster to the I atoms, where the populations for Al(14) vary from -0.70(Al(14)I(-)) to +0.96(Al(14)I(11) (-)). The Al(14)I(5) (-) and Al(14)I(7) (-) clusters have the structure of Al(14)I(3) (-) as a core framework, but, for n=9 and 11, we found many more stable isomers than the isomers having the Al(14)I(3) (-) core. In particular, the shape of Al(14) in the Al(14)I(11) (-) cluster is a hexagonal wheel-shaped form, which was observed in the x-ray experiment for the metalloid complex [Al(14){N(SiMe(3))(2)}(6)I(6)Li(OEt(2))(2)](-)[Li(OEt(2))(4)](+)toluene [Kohnlein et al., Angew. Chem., Int. Ed. 39, 799 (2000)]. We have demonstrated that a simple jellium model cannot describe the structure and stability of the iodine-doped aluminum clusters, although it is successful for describing those of aluminum clusters. The electronic and geometric changes of the Al(14) (-) cluster due to the presence of iodines are very similar to the case of a magic cluster Al(13) (-). It can be concluded from our electronic and structural analysis that one cannot regard the Al(14) core as an alkaline earthlike superatom in the Al(14) iodide clusters.     

SYNTHESIS OF 11 α-HYDROXY-AND 11β-CHLORO-ARTEMISININ

11α-Hydroxy-and 11β-chloro-artemisinin have been prepared from artemisinin     

Synthesis of 14-Bromo and 14-Hydroxy Baccatin III Derviatives

Numerous efforts towards synthesis of anticancer drug paclitaxel (Taxol(r), 1a) with improved activities led to the modification at 13-phenylisoserine side chain and different positions of its core structure-baccatin III 1c1. At the same time, the activities of searching new taxoids for starting materials of new semi-synthetic paclitaxel analogs from Taxus spp. plant have not ever been stopped. Among these taxoids, 14?-hydroxy-10-deacetylbaccatin III 22 and 13-acetyl-9-dihydrobaccatin III …     

Synthesis and some properties of Nd(B11H14)3 · 4Dg (Dg is diglyme)

The reaction of Nd(BH₄)₃ · 3THF with decaborane-14 in diglyme at 85–90°C yields Nd(B₁₁H₁₄)₃ · 4Dg. The duration of the reaction is 20 h. The molar ratio of Nd(BH₄)₃ · 3THF to B₁₀H₁₄ is is 1 :3.5. The product is precipitated with heptane from a diglyme solution. The yield is 70%. In an inert atmosphere, Nd(B₁₁H₁₄)₃ · 4Dg is stable to 150°C and decomposes with an exotherm at 160–190°C. The IR spectrum of Nd(B₁₁H₁₄)₃ · 4Dg in the region of B-H stretching vibrations contains an intense band at 2530 cm^?1. The ¹¹B {¹H} NMR spectra of the synthesized compound in diglyme solutions contain signals of the tetradecahydro-nido-undecaborate anion B₁₁H ₁₄ ^? (δ = -14.0, -15.6, and -16.5 ppm).     

联苯型[11], [14]和[17]环系氮杂支链套索冠醚的合成

以碳酸钾为缩合剂, 2,2'-二羟基联苯分别与二对甲苯磺酸酯Ⅱa~c, Ⅳb,Ⅵb反应合成尚未见文献报道的联苯型单氮杂冠醚(1~3), 二氮杂冠醚9和11。3,9和11分别用氢溴酸去对甲苯磺酰基得到亚胺型氮杂冠醚4, 10和12。4与溴代烃RBr(R=-(CH2)3CH3, -CH2CH=CH2, -(CH2)7CH3, -(CH2)2O(CH2)2OC4H9)反应分别合成[11]环系氮支套索冠醚(5~8), 12与正溴丁烷反应合成[17]环系氮支冠醚13。以上13种化合物皆为新型未见文献报道, 其结构皆经元素分析, IR, ^1H NMR,MS确证。     

14N16O的LMR光谱测量及其相关同位素分子14N17O和14N18O的光谱分析

采用内脏式ＣＯ激光磁共振（ＬＭＲ）技术测量了~(14)Ｎ~(16)Ｏ的Ｘ~Ｘ Ｚｅｅｍａｎ跃迁谱，并对其进行了标识、在Ｈｕｎｄ情形（ａ）双原子分子结构模型的基础上，采 用先进的同位素分子参数标度函数，对已发表的~(14)Ｎ~mＯ（ｍ＝ １６， １７， １８）光谱实验数据及 测量的 ＬＭＲ光谱数据进行了统一的分析计算，得到~14Ｎ~16Ｏ分子基态的精确结构参数， 其精度比前人的结果提高了 １－ ２个数量级，并由此推导出~(14)Ｎ~(17)Ｏ及~(14)Ｎ~(18)Ｏ等同位素分 子的结构参数．     

杂多酸盐K_4H(SiMo_(11)VO_(40))·14H_2O的合成及晶体结构

杂多酸是种类多,应用广的重要的无机化合物。其中有一类是12-系列化合物Z,(XM_(12-n)M_n′O_(40))·mH_2O,中心离子X可以是过渡元素或非过渡元素;M常是Mo、W;M′为V_(5 )、Mn_(2 )、CO_(2 )等;n=0,1,2…;Z为H~ 或一价阳离子;y=1,2,…。它们同其相应氧化型化合物比较具有引人注目的特性,但迄今尚未见到还原型化合物晶体结构文章,只是     

SAPO-11分子筛的合成

以二正丙胺(DPA)为模板剂、利用水热法合成SAPO-11分子筛，系统考察了硅源、硅含量、模板剂用量以及晶化条件（晶化温度、时间以及pH值）对SAPO-11分子筛合成的作用。研究结果表明：硅源是决定SAPO-11分子筛合成及结构的关键组分之一，其释放出活性硅物种的速率要与磷酸铝分子筛的前驱体生成的速度相一致；酸性硅溶胶是合成SAPO-11的合适硅源；在SiO2/Al2O3=0～0.7，DPA/P2O5=0.8～1.8，pH=5.8～7.8条件下，可合成纯SAPO-11分子筛。此外，SAPO-11分子筛的合成，还存在明显的诱导期以及晶型的转化过程。在合成条件下，晶化时间4?h时，SAPO-11开始晶化，至24 h，SAPO-11分子筛可晶化完全。继续延长晶化时间，SAPO-11分子筛与SAPO-31分子筛之间发生转晶现象。     

水-丁醇两相介质合成SAPO-11和MgAPO-11分子筛

在水-丁醇两相介质中合成了SAPO-11和MgAPO-11分子筛.水-丁醇两相介质有利于在SAPO-11中引入更多的Si,从而产生较多的酸性位,以所得SAPO-11为载体的Pt催化剂在正十二烷临氢异构化反应中表现出较高的催化活性.相反,水-丁醇两相介质不利于Mg进入分子筛骨架,导致MgAPO-11上的酸性位减少,Pt/MgAPO-11催化剂的催化活性降低.     

Photochromismof11－TungstophosphateinDMFsolution

Ｐｈｏｔｏｃｈｒｏｍｉｓｍｏｆ１１－ＴｕｎｇｓｔｏｐｈｏｓｐｈａｔｅｉｎＤＭＦｓｏｌｕｔｉｏｎ￣＊／／ＹＵＥＢｉｎ￣,ＣＨＥＮＫａｉ,ＬＩＵＨｕｉ－ｚｈａｎｇ,ＺＨＵＳｉ－ｓａｎａｎｄＸｉｅＧａｏ－ｙａｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ...     

P14原子簇的理论研究

以Ｐ_２、Ｐ_４（Ｔｄ）、Ｐ_８（Ｃ_（２ｖ））及Ｐ_（１０）（Ｃ_（２ｖ））为结构单元设计了Ｐ_２＋Ｐ_４（Ｔ_ｄ）＋Ｐ_８（Ｃ_（２ｖ））→Ｐ_（１４）（Ｃ_ｓ）（Ａ）、Ｐｓ（Ｃ_（２ｖ）＋３Ｐ_２→Ｐ_（１４）（Ｃ_（２ｖ））（Ｉ）（Ｂ）、Ｐ_（１０）（Ｃ_（２ｖ）＋２Ｐ_２→Ｐ１４（Ｃ_（２ｖ））（Ⅱ）（Ｃ），利用从头算Ｇａｕｓｓｉａｎ－９４程序，选择６－３１Ｇ基组，对４种结构单元及Ｐ_（１４）原子簇的３种几何构型Ｃｓ、Ｃ_（２ｖ）（Ⅰ）、Ｃ_（２ｖ）（Ⅱ）进行全优化。相对能量的计算结果表明，Ｐ_（１４）（Ｃ_ｓ）与Ｐ_（１４）（Ｃ_（２ｖ））（Ⅰ）构型稳定。进一步设计（７／２）Ｐ_４（Ｔ_ｄ）→Ｐ_（１４）（Ｄ）及７Ｐ_２→Ｐ_（１４）（Ｅ），其相对能量表明，Ｐ_（１４）（Ｃ_ｓ）构型是稳定的．磷与磷连结单键键长范围为０．２２０～０．２２８ｎｍ，双键键长范围为０．２００～０．２０２ｎｍ，与实验结果大体相当。