龙眼三萜-A的晶体结构

用直接法测定了龙眼三萜-A的晶体结构。晶体属单斜晶系, 空晶群C2, 晶胞参数:a=1.3419(4), b=0.6422(2), c=2.9586(7)nm, β=91.91(2)°, Vc=2.548(1)nm^3;z=4, Dc=1.12g/cm^3, Dm=1.10g/cm^3, F(000)=960。结构在MICRO VAX 计算机上用TEXSAN程序包求解、晶体结构用全矩阵最小二乘法修正, 得到最后的偏离因子R=0.068。     

复合硬垢物相分析

本文报道采用灼烧有效处理一种工业的复合硬垢,用红外光谱和X射线粉末衍射方法,确定该样品由CaC_2O_4·H_2O、α-Fe_2O_3、Ca_(0.9)Mg_(0.1)CO_3固溶体、(Mg,Fe)_2Al_4Si_5O_(18)及炭质物构成。第一次发现堇青石(Mg,Fe)_2Al_4Si_5O_(18)存在于工业污垢中。对方解石Ca_yMg_(1-y)CO_3的Ca/Mg比例和分解温度进行了讨论。     

Synthesis and structure of linear hexanuclear manganese (Ⅱ)benzoate cluster

From a reaction system including benzoic acid and Mn(NO3)2 in alkali medium, two hexanuclear manganese benzoate cluster compounds have been synthesized. A compound [Et4N]2[Mn6(PhCOO)14] has been structurally characterized, which contains hexanuclear Mn11 moieties extending unlimitedly to form one-dimensional linear structure. Carboxyl oxygen atoms are bridged in variety of modes to the Mn atoms, forming an arrangement like a sinusoid for the Mn atoms. The structural parameters of these compounds were compared with the data obtained from EXAFS determination for the Mn cluster in the OEC of PS11, supporting that the coordination sphere of the Mn site in the OEC may contain carboxyl bridges. The possible combination modes between the carboxyl group and the Mn atoms have been suggested. The NMR signals exhibit widening and shift produced by the influence of the paramagnetic Mn" sites. The red-shift of the absorption in IR spectrum was observed to be attributed to the coordination of the carboxyl group to the Mn     

Synthesis and Crystal Structure of a Puckered Rhombus Grid-like Coordination Polymer with Bridging Ligand Containing Sulfanyl Linker

Introduction The design and construction of metal-organic frameworks (MOFs), obtained by metal-directed self-assembly from labile metal centers and multidentate bridging ligands, is a rapidly developing area of su-pramolecular chemistry.1-3 Besides the aesthetic struc-tural and fascinating functional motifs, they are of in-terest both for understanding the mechanisms of the assembly process and for the host-guest chemistry asso-ciated with their large central cavities.4-13 It has been documen…     

CRYSTAL STRUCTURE AND POWDER DIFFRACTION OF Na5Y（WO4）4

<正> Title compound Na5Y (WO4)4 (Mr = 1195. 24) crystallizes in the space group I41/a with the cell parameters a= 11. 447(7), c= 11. 336(1) A , Z = 4, V = 1485(2) A3, A = 5. 34 g/cm3. A(MoKα) = 0. 71069 A. F(000) = 2702, final R = 0. 045,Rw = 0. 054 for 936 observed reflections with I≥3σ(I). The title compound has a scheelite structure.In this paper, we also give the X-ray powder diffraction data of Na5Y(WO4)4 obtained by using a D/max-ra type diffractometer.     

Syntheses of a new type of chiral phosphines from glucose

Methyl 3-deoxy-3-(diphenylphosphino)-4,6-O-benzylidene-α-D-altropyranoside (1) and methyl 2-deoxy-2-(diphenylphosphino)-4,6-O-benzylidene-α-D-altropyranoside (2) were prepared from methyl 2,3-anhydro-4,6-O-benzylidene-O-D-mannopyranoside and methyl 2,3-anhydro-4,6-O-benzyl-idene-α-D-allopyranoside,respectively,via regioselective and stcreospecific ring-opening reactions in high yields.Compounds 1 and 2 were oxidized to give the corresponding phosphine oxides (3 and 4).     

CRYSTAL STRUCTURE OF A TRINUCLEAR COBALT COMPLEX Co_3(bdt)_3(PBu_3~n)_3 · ~2CH_2C1 (bdt = S_2C_6H_4~2- ) WITH MIXED o-BEN-ZENEDITHIOLATE AND TRIBUTYLPHOSPHINE LIGANDS

<正> Co3(S2C6H4)3{P(C4H9)3}3 ·2CH2Cl2, Mr = 1373. 45, mono-clinic, space group P21/c, a = 16. 110(5), b=36.313(10), c=13. 502(5) A , β= 105. 69(4)% V=7604. 4 A3, Z = 4, Dc = 1. 20 g. cm-3, μ=10. 03 cm-1, and F (000) = 2990. R(Rw) is 0. 086(0. 091) for 4559 observed unique reflections. The three cobalt atoms in the complex form an isosceles triangle with an average Co -Co bond distance of 2. 504(5) A. The average values of Co - S and Co - P bond distances are 2. 271(7) A , and 2. 198(8) A , respectively.     

关于ABS树脂热失重数据的计算

在解析TG曲线时,常用的方法有积分法和微分法,但反应级数需要通过预先假定和尝试确定.本文以ABS树脂热解反应为对象,采用三次样条插值函数求得热解反应速率,利用二元线性回归经一次计算,同时求得ABS树脂热解反应表观活化能E,视频因子A以及反应级数n,并把所得结果与积分法和微分法作了比较,确定了各自方法所适用的转化率区间.本文还考察了不同升温速率对热解动力学参数的影响.     

Synthesis and Crystal Structure of a Decanuclear Silver(Ⅰ)-thiolate Compound Ag_(10)S[S_2P(OEt)_2]_8

Introduction Polynuclear Ag(I)-thiolate compounds are of interests due to their unique molecular structures and metal-metal interactions. There were some such compounds reported in literatures, including Ag8(6-S)(dtp)6 [dtp=S2P(OEt)2] with [Ag8] cube,1 {Ag[S2P(OC3H7)2]}6 with a [Ag6] distorted octahedron,2 Ag11S(Et2dtc)9 [Et2dtc=S2CN(C2H5)2] with a [Ag11] cage of a 3-fold axis,3 and Ag14(6-S)(SPh)12(PPh3)8 4CH3OH13H2O with a [Ag14S12] cage composed of a staggered [Ag6] octahedr…     

Bonding of the chain structure for novel boranes B_(3k+)H_(5k+p+3)~-

The molecular orbitals obtained from conventional quantum chemistry calculations, are expressed in terms of symmetrized valence bond functions of fragment, and a direct picture of chemical bonding can be drawn easily. This method is utilized, together with extended Huckel calculations, to interpret the bonding properties of a centipede-like chain structure for novel laser-producing boranes B3k+pH5k+p+3- which is constructed from the repeated unit B3H5 linked to each other by three B-H-B bonds.