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991.
The Crystal Structure of Na2NiAlF7 — a Contribution to the Problem of the True Space Group of Orthorhombic Weberites The X-ray single crystal structure determination of the orthorhombic weberite Na2NiAlF7 (a = 707.4(2), b = 1003.8(2), c = 731.5(1) pm; Z = 4) was performed in space group Imma, after all reflections hk0 with h(k) = 2n + 1 could be eliminated, as they proved simulated by Renninger effect and/or λ/2 reflections. The alternative space groups Imm2 resp. I212121 of former weberite structure determinations thus became obsolete. The refinement using 880 independent reflections ended at wR = 0.0232. The resulting average distances within the framework of octahedra are Ni? F = 197.3, Al? F = 180.4 pm. 相似文献
992.
YueMingLIU FengMeiZHANG HaiHongWU HaiJiaoZHANG JianGuoYANG XingTianSHU MingYuanHE 《中国化学快报》2004,15(10):1258-1260
A SAPO-11 silicoaluminophosphate molecular sieve with stable crystal structure was synthesized for the first time. After removing template by calcination, its crystal space group still retains Icm2 which the as-synthesized has. The catalyst deriving from the present SAPO-I 1 materials shows higher isomerization selectivity and higher paraffin hydroisomerization yield than those reported elsewhere. 相似文献
993.
A novel compound Ni(phen)(H2O)(V2O6) has been hydrothermally synthesized and structurally determined to be a two-dimensional compound, which contains {V2O6}n2n- chains interconnected by nickel(Ⅱ) complexes via oxygen atoms. The crystallographic data measured by single-crystal X-ray diffraction analysis are as follows: C12H10N2NiO7V2, Mr=454.81, monoclinic, space group P21/c, a=0.784 6(3), b=2.103 6(8), c=0.942 3(4) nm, β=112.872(5)°, V=1.433 0(10) nm3, Z=4, Dc=2.104 Mg·m-3, μ(Mo Kα)=2.615 mm-1, F(000)=904, T=298(2) K, 4 480 reflections collected, 2 470 independent (Rint=0.032 2), the final R=0.058 4 and wR2=0.145 7 for 2 303 observed reflections with I>2σ(I). CCDC: 192520. 相似文献
994.
医用聚氯乙烯膜的等离子体表面改性 总被引:4,自引:0,他引:4
用两种不同气氛的辉光放电等离子体工艺对医用软质聚氯乙烯(PVC)膜进行了表面改性研究。结果表明,聚合性气氛的等离子体改性效果明显优于非聚合性气氛。平整致密的聚合膜对PVC增塑剂——邻苯二甲酸二辛酯的迁移和扩散起了阻挡作用,也使膜表面亲水性和表面张力极性成份增大,液固相界面张力减小,生物相容性得以改善。 相似文献
995.
A Contribution on the Crystal Structure of CuYW2O8, CuHoW2O8, and CuYW2O8 Single crystals of (I) CuY2O8, (II), CuHoW2O8, and (III) CuYbW2O8 were prepared and investigated by X-ray technique. (I) crystallizes with triclinic symmetry, space group C? P1 (a = 5.939 Å, b = 6.042 Å, c = 5.025 Å; α = 112.30°, β = 111.77°; Z = 1). (II) and (III) belong to monoclinic symmetry, space group C? P2/n (II) (a = 10.045 Å, b = 5.808 Å, c = 5.021 Å; β = 94.38°; z = 2 (III) a = 9.948 Å, b = 5.824 Å, c = 5.008 Å; β = 93.36°; Z = 2). The crystal structures will be discussed with respect to other to copper rare earth tungstates. 相似文献
996.
Sadafumi NishiharaTomoyuki Akutagawa Tatsuo Hasegawa Shigeki FujiyamaToshikazu Nakamura Takayoshi Nakamura 《Journal of solid state chemistry》2002,168(2):661-667
Two polymorphs of monovalent [Ni(dmit)2]− (dmit2−=2-thioxo-1,3-dithiole-4,5-dithiolate) crystals A and B, (anilinium)(18-crown-6)[Ni(dmit)2], were prepared, and the structure and magnetic properties were investigated. In these crystals, the [Ni(dmit)2]− molecules form dimers, which arranged into chains between the supramolecular cation structure (anilinium)(18-crown-6). In crystal A, supramolecular cation formed a regular stack, inducing ladder structure of [Ni(dmit)2], whose magnetism had been well fitted by spin ladder equation with the spin gap of Δ=190 K. Crystal B is ca. 3% more densely packed compared to crystal A. Due to the dense packing, supramolecular cation stack is distorted, which prevented the intermolecular interaction between [Ni(dmit)2]− dimers in direction corresponds to the ladder-leg direction in crystal A. Reflecting the [Ni(dmit)2]− arrangement, crystal B showed a temperature dependence of magnetic susceptibility well reproduced by the singlet-triplet thermal activation model, whose antiferromagnetic exchange interaction (2J) was 140 K. 相似文献
997.
Introduction As an important type of fungicides, triazole compounds are highly efficient, low poisonous and inward absorbent.1-3 At present, the studies on triazole derivatives are mainly concentrated on compounds with triazole as the only active group. The report of triazole compounds that contain both triazole group and other active group in a single molecule has rarely been found. Dialkyl-substituted dithiocarbamate salts have also shown interesting biological effects.4 N,N-Dialkyldithio-… 相似文献
998.
分别合成了 [Co(3, 3-tri)(men)Cl][ZnCl4]、[Co(3, 3-tri)(cmen)Cl][ZnCl4] (3, 3-tri = N-(3-胺基丙基)-1, 3-丙二胺,men = N-甲基乙二胺,cmen = 1, 2-二胺基-丙烷) 2体系的部分配合物异构体,用单晶 X-射线衍射分析方法解析了2异构体的晶体结构。其中 [Co(3, 3-tri)(men)Cl][ZnCl4] 体系的一异构体Ⅰ的化学简式为 CoCl(C9H27N5)ZnCl4,晶体属正交晶系,空间群 Pca21,a = 16.788(2),b = 7.964(1),c = 14.416(2) 牛琕 =1927.3(4) ?,Dc = 1.747 g/cm3,Z = 4,F(000) = 1032,Mr = 506.91,R = 0.0352,wR =0.0935;[Co(3, 3-tri)(cmen)Cl]2+ 体系的一异构体Ⅱ的化学简式为 CoCl(C9H27N5)ZnCl4稨2O, 晶体属三斜晶系,空间群 P ,a = 9.511(3), b = 9.972(3),c = 11.694(3) 牛琣 = 68.367(5),b = 85.196(6),?= 86.580(5),V = 1026.9(5)?3,Dc = 1.698 g/cm3,Z = 2,F(000) = 536,Mr = 524.92,R = 0.0494,wR = 0.1180。两异构体中 Co3+ 为六配位,晶胞中对映体比例均为1:1。在配合物异构体Ⅰ和Ⅱ中,三元胺以经式排布,三元胺配体(3, 3-tri)仲胺上的氢相对于Cl分别处于顺位(syn-)和反位(anti-);二元胺配体氮(或邻位碳)取代的胺基氮原子(N*)与三元胺配体中的仲氮原子分别处于对位(trans(N*))和邻位(cis(N*))。 相似文献
999.
A re-usable and sensitive cryptand-22-coated quartz-crystal membrane piezoelectric sensor with a homemade computer interface for signal acquisition and data processing was prepared and applied as a gas-chromatographic (GC) detector for various organic molecules. The oscillating frequency of the quartz crystal decreased due to the adsorption of organic molecules on cryptand-22. Effects of functional group, molar mass, steric hindrance and polarity of organic molecules on frequency responses of the cryptand-coated piezoelectric crystal detector were investigated. The cryptand-coated piezoelectric crystal GC detector had demonstrated high sensitivity for various polar organic molecules and good reproducibility when re-used. The frequency responses of the cryptand-coated crystal for various molecules were in the following order: carboxylic acids (RCOOH)primary amines (R-NH2)>alcohols (ROH)>secondary amines (R2NH)>tertiary amines (R3N)>ketones. More polar molecules exhibited better frequency responses. The effect of temperature and amount of coating on the frequency responses of cryptand-coated crystal GC detector were also investigated. The cryptand-coated piezoelectric crystal GC detector compared well with the commercial thermal conductivity detector (TCD). 相似文献
1000.
Ali Jabalameli Andrzej Nowek Richard H. Sullivan Jerzy Leszczyński 《Structural chemistry》1997,8(4):245-256
Ab initio studies (LCAO-MO method) on conformers of three seleno derivatives of the biuret molecules diselenobiuret [I], selenobiuret [II], and selenothiobiuret [III] were carried out at the Hartree-Fock (HF) and MP2 levels. The molecular geometries of these species were fully optimized at the HF level and characterized by analysis of the harmonic vibrational frequencies using a split-valence triple-zeta basis set augmented by a set ofd polarization functions on heavy atoms andp polarization functions on hydrogen atoms [TZP(d, p)]. The total energies of the HF-optimized structures were calculated at the MP2 (frozen core) level using a larger TZP (2df, 2pd) basis set. The potential energy searches revealed a total of 11 minimum-energy conformers (assigned astrans-trans, trans-cis, cis-trans, andcis-cis) and seven transition-state species for the title molecules. The two predicted conformers for diselenobiuret (Ia=trans-trans andIc=cis-cis) are characterized byC
2 and the third byC
s symmetry. For selenothiobiuret two forms (IIIa=trans-trans andIIId=cis-cis) possessC
1 and two (IIIb=trans-cis andIIIc=cis-trans) possessC
s symmetries, respectively. For selenobiuret, four formsIIa=trans-trans (C1),IIb=trans-cis (C
s),IIc=cis-trans (C
1), andIId=cis-cis (C1), were obtained as a result of gradient optimization. Comparison of the relative energies for the considered species indicated that thecis-trans forms are the most stable conformations for all three systems at both the HF and MP2 levels of theory. 相似文献