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81.
Investigation of the LaI2/H2 System: Phase Relations and Stacking Disorder Heating of LaI2 under 1 bar hydrogen pressure to 650 °C leads to light gray LaI2H0.95(3), accompanied by a structural change from tetragonal to hexagonal. Sharp reflections in the XRD pattern can be indexed in P63/mmc with a = 4.2158(7)Å and c = 15.508(3)Å, however, diffuse reflections indicate the presence of stacking faults in the structure, which correspond to a polytypic intergrowth of MoS2 and NbS2 type structural fragments. Increasing the reaction temperature to 730 °C results in a better defined diffraction pattern with the peak positions close to those of the 2H‐NbS2 structure type. An X‐ray powder study of the samples LaI2Hn proved the miscibility gap between LaI2 and LaI2Hn (0 ≤ n ≤ 0.5) in agreement with previous results. With decreasing H‐content of the homogeneous phase the lattice parameters change in opposite direction, a increasing to 4.236(1)Å and c decreasing to 15.39(2)Å for the lower limit. 相似文献
82.
The novel ionic ozonide {[N(C4H9)4](O3)}4·4.75NH3 was synthesized by ion‐exchange reaction in liquid ammonia. The crystal structure was determined by single crystal diffraction at 100 K (monoclinic space group P21, a = 15.014(11) Å, b = 13.696(10) Å, c = 19.890(15) Å, β = 105.407(12)°, V = 3943(5) Å3, Z = 2). The structure consists of a packing of sandwich‐like dimeric ion pairs in which two ozonide anions are interspersed between two tetrabutylammonium cations. Ammonia molecules from the solvent are localized in cavities in the structure. They are involved in hydrogen bonding with the ozonide ions. The desolvated tetrabutylammonium ozonide forms stable solutions in dichloromethane which may open up novel possibilities of tapping into the synthetic potential of the ozonide ion. 相似文献
83.
Joachim Janssen Holger Rumpf Hartwig Modrow Ralf Rablbauer Georg Frommeyer Josef Hormes 《无机化学与普通化学杂志》2003,629(10):1701-1708
The surface oxidation of FeCr alloys with 18, 28, and 43 mass‐% Cr was investigated in situ using grazing‐incidence X‐ray absorption spectroscopy (GIXAS) at the chromium and iron K‐edges. Oxidation in air was monitored in situ in the temperature range from 290 K to 680 K. The standard GIXAS data analysis is extended for the treatment of a single layer model in order to estimate the chromium concentrations of the oxide layer and of the near‐interface substrate as well as the oxide layer thickness. XANES analysis shows transitions from b.c.c. Fe to corundum type Fe2O3 and from b.c.c. Cr to corundum type Cr2O3. The initial oxide layers are 1.1‐1.4 nm thick and contain 60‐90 mass‐% chromium, while the near‐interface substrate is depleted in Cr. During heating, iron oxide growth dominates up to 560‐600 K. Then the chromium oxide layer loses its passivation effect and Cr oxidation sets in. 相似文献
84.
甲烷二氧化碳重整制合成气反应过程中,催化剂表面积炭是制约催化反应顺利进行的关键因素。研究催化剂表面积炭物种及积炭速率,找出影响催化剂表面积炭的动力学因素,对建立合理的催化重整反应体系,完善催化剂表面积炭的动力学理论具有重要的理论和实际意义。目前有关催化剂表面积炭速率的研究报道较少[1,2]。Ni基六铝酸盐催化剂对甲烷二氧化碳重整制合成气具有很好的催化活性和稳定性[3,4]。本文利用X 射线光电子能谱(XPS)和热重分析(TGA)技术,在还原态Ni基六铝酸镧LaNiAl11O19催化剂表面研究了甲烷裂解积炭和甲烷二氧… 相似文献
85.
86.
McGowan G Parsons S Sadler PJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(15):4396-4404
cis-[PtCl2(NH3)(2-picoline)] (AMD473) is a sterically-hindered anticancer complex with a profile of chemical and biological activity that differs significantly from that of cisplatin. Adducts of AMD473 with neutral 9-ethylguanine (9-EtGH) and anionic (N1-deprotonated) 9-ethylguanine (9-EtG) as perchlorate and nitrate salts, and also a nitrate salt of the trans isomer (AMD443), were prepared and their structures determined by X-ray crystallography: cis-[Pt(NH3)(2-pic)(9-EtGH)2](ClO4)2 (1).2H(2)OMe(2)CO, cis-[Pt(NH3)(2-pic)(9-EtGH)2](NO3)2 (2).2H2O, cis-[Pt(NH3)(2-pic)(9-EtGH)(9-EtG)]NO3 (3),3.5 H2O, trans-[Pt(NH3)(2-pic)(9-EtGH)(9-EtG)]NO3 (4).8H2O. In all cases, platinum coordination is through N7 of neutral (1, 2) and anionic (3, 4) guanine. In each complex, the guanine bases are arranged in the head-to-tail conformation. In complex 1, there is an infinite array of six-molecule cycles, based on both hydrogen bonding and pi-pi stacking of the 2-picoline and guanine rings. Platinum(II) coordinated at N7 acidifies the N1 proton of neutral 9-ethylguanine (pKa = 9.57) to give pKa1 = 8.40 and pKa2 = 8.75 for complex 2, and pKa1 = 7.77 and pKa2 = 9.00 for complex 4. In complexes 3 and 4, three intermolecular hydrogen bonds are formed between neutral and deprotonated guanine ligands involving O6, N1 and N2 sites. Unusually, both of the platinated guanine bases of complexes 3 and 4 participate in this triple G triple bond G hydrogen bonding. This is the first report of X-ray crystal structures of nucleobase adducts of the promising anticancer drug AMD473. 相似文献
87.
The graphite‐like yttrium hydride halides, YIHn (0.8 ? n ? 1.0), have been prepared in quantitative yields by heating either YI3, YH2 (1:2) or stoichiometric YI3, YH2, Y mixtures in sealed Ta ampoules at 900°C. A lower limit of the homogeneity range, n ≈ 2/3, has been determined from dehydrogenation experiments. All YIHn phases adopt the ZrBr‐type heavy‐atom structure. The hydrogen variation is accompanied by a change in the c lattice constant from 31.162(3) to 31.033(1) Å for n = 0.61(3) to 1.02(3). The YIHn phases reversibly react with hydrogen at 400‐600°C to form the light green transparent compound YIH2. However, increasing the reaction temperature above 700°C causes decomposition to an unidentified phase being in equilibrium with YH2 and YI3. The arrangement of the heavy atoms in YIH2 (P m1; a = 3.8579(3) Å, c = 10.997(1) Å) corresponds to a four‐layer I‐Y‐Y‐I slab with the stacking sequence (AbaB) as was found by x‐ray powder diffraction data refinement with the Rietveld method. A miscibility gap exists between YIH and YIH2. Samples YIHn (n ? 1.0) show metallic conductivity at room temperature, which changes into semiconducting behavior with decreasing temperature as n approaches its lower value ≈ 2/3. 相似文献
88.
89.
The cubic inverse Perovskites (Eu3O)In and (Eu3O)Sn were prepared from the metals and Eu2O3 or SnO2, respectively. For (Eu3O)In the crystal structure analysis was performed on single crystal X‐ray diffraction data (space group , a = 512.79(3) pm, Z = 1, Rgt(F) = 0.022, wR(F2) = 0.044). The data indicated full occupancy on all sites and a fully ordered structure. According to magnetic susceptibility measurements and X‐ray absorption spectroscopic data at the Eu LIII edge both compounds contain europium in the 4f7 (Eu2+) electronic state. (Eu3O)In orders ferromagnetically at 185(5) K, (Eu3O)Sn shows antiferromagnetic order at 31.4(2) K. Both compounds behave as metallic conductors in electrical resistivity measurements. However, (Eu3O)In may be classified a metal, while (Eu3O)Sn is more likely a heavily doped degenerated semiconductor or semimetal according to the absolute values of the resistivity. 相似文献
90.
The reaction of the rifle cyclic complex (1) with sodium amalgam in THF resulted in the expected cleavage of the Fe-Fe bond to afford his-sodium salt ( Me2SiSiMe2 ) [η^5-C5H4Fe(CO)2]2 (4). The latter was not isolated and was used directly to react with MeI, PhCH2Cl, CH3C(O)Cl, PhC(O)Cl,Cy3SnCl (Cy= cyclohexyl) or Ph3SnCl to afford corresponding ring-opened derivatives (Me2SiSiMe2) [η^5-C5H4Fe(CO)2]2 [5, R=Me; 6, R=PhCH2; 7, R=CH3C(O); 8, R=PhC(O); 9, R = Cy3Sn or 10, R = Ph3Sn ]. The crystal and molecular structures of 10 were determined by X-ray diffraction analysis. The molecule took the desired ant/ conformation around the Si-Si bond. The length of the Si--Si bond is 0.2343(3)nm, which is essentially identical to that in the cyclic structure of 1[0.2346(4) tun]. This result unambiguously demonstrates that the Si--Si bond in the cyclic structure of 1 is not subject to obvious strain. 相似文献