(η~5-C_5H_5)Ln(η~8-C_8H_8)(THF)_n(Ln=Pr,Nd,Gd)的合成及(η~5-C_5H_5)Pr(η~8-C_8H_8)(THF)_2的晶体结构

自1969年首次报道稀土环辛四烯基化合物Eu(C_8H_8)和Yb(C_8H_8)的合成以来,相继合成K[Ln(C_8H_8)_2],[Ln(C_8H_8)Cl·2THF]_2和[Ln(C_8H_8)·2THF]等,还报

SYNTHESIS AND CRYSTAL-STRUCTURE OF A NEW LANTHANIDE CYCLOOCTATETRAENE COMPLEX (ETA-8-C8H8)ER(MU-ETA-8-C8H8)K(MU-ETA-8-C8H8)ER(MU-ETA-8-C8H8)K(THF)4

The tetranuclear nearly-linear complex (eta-8-C8H8)Er(mu-eta-8-C8H8)K(mu-eta-8-C8H8)Er(mu-eta-8-C8H8)K(THF)4 (THF = tetrahydrofuran) is first synthesised by the reaction of benzylcyclopentadienyl erbium dichloride (PhCH2C5H4)ErCl2.3THF with cyclooctatetraenyl potassium K2C8H8 in 1:1 molar ratio in THF; a single crystal X-ray study has shown that the complex has the tetralayer-sandwich structure and that the adjacent Er3+ and K+ ions are bridged by eta-8-cyclooctatetraenyl group.

THE SYNTHESES OF THE COMPLEXES (ETA-5-C5H5)LN(ETA-8-C8H8).NTHF AND (ETA-5-C9H7)LN(ETA-8-C8H8).2THF AND THE CRYSTAL-STRUCTURE DETERMINATION OF (ETA-5-C5H5)PR(ETA-8-C8H8).2THF AND (ETA-5-C9H7)PR(ETA-8-C8H8).2THF

LnCL3 reacts with NaC5H5 and K2C8H8 to yield the complexes (eta-5-C5H5)Ln(eta-8-C8H8).nTHF (Ln = Pr, Nd, n = 2; Ln = Gd, n = 1) and LnCl3 reacts with KC9H7 and K2C8H8 to yield the complexes (eta-5-C9H7)Ln(eta-8-C8H8).2THF (Ln = Pr, Nd; eta-5-C9H7 = indenyl); crystallography reveals (eta-5-C5H5)Pr(eta-8-C8H8).2THF and (eta-5-C9H7)Pr(eta-8-C8H8).2THF not to possess the parallel ring sandwich structure.

A~NB~(8-N)型晶体中的化学键和硬度

我们在晶体化学键的研究中得出这样的结论,晶体硬度正象其他宏观量一样,是其微观特性的宏观反映,我们通过对一些晶体的研究比较,给出了AB型晶体化学键参数和硬度之间的定量关系一经验公式,并对六十多种晶体的硬度进行了计算,结果和实验测定值符合很

Sr_3Cu_5O_(8+x)和CaSrCu_5O_(5+x)的结构和电学性质

继Y-Ba-Cu-O之后,具有更高T_5的Bi-Sr-Ca-Cu-O(简称BSCCO)体系的发现引起了人们对高温超导研究的兴趣。研究表明,在BSCCO中存在110K和80K2个超导相。由于在制备BSCCO过程中存在复杂的Ca、Sr和Cu复合氧化物,要得到稳定的110K相相当困

5,7-Dihydroxy-5,6,7,8-tetrahydro-1H-azocin-2-one from a marine-derived Streptomyces sp.

In the course of a screening program, we have isolated the new natural product, 5,7-dihydroxy-5,6,7,8-tetrahydroazocin-2(IH)-one (1), from the staurosporine producing marine-derived Streptomyces sp. strain QD518. Here we report the isolation and structure elucidation of 1 and the artifacts 3 and 4 resulting from I by acid catalyzed intra- and inter-molecular reactions.

Development of the East Asian summer monsoon: Evidence from the sediment record in the South China Sea since 8.5 Ma

128 samples from Ocean Drilling Program (ODP) Site 1143 in the southern South China Sea were analyzed for grain size, clay minerals, biogenic opal content and quartz in order to reconstruct changes in East Asian monsoon climate since 8.5 Ma. An abrupt change of terrigenous mass accumulation rate (MAR), clay mineral assemblage, median grain size and biogenic opal MAR about 5.2 Ma suggests that between 8.5-5.2 Ma the source of terrigenous sediment was mainly in the region of surface uplift and basaltic volcanism in southern Vietnam. A simple model of East Asian summer monsoon evolution was based on the clay/feldspar ratio, kaolinite/chlorite ratio and biogenic opal MAR. The summer monsoon has two periods of maximum strength at 8.5-7.6 Ma and 7.1-6.2 Ma. Subsequently, there was a relatively stable period at 6.2-3.5 Ma, continued intensification about 3.5-2.5 Ma, and gradually weakening after 2.5 Ma. Since I Ma the monsoon has intensified, with remarkable high-frequency and amplitude variability. Simultaneous increase in sedimentation rates at ODP Sites 1143, 1146 and 1148, as well as in MAR of terrigenous materials, quartz, feldspar and clay minerals at ODP Site 1143 at 3.5-2.5 Ma, may be the erosional response to both global climatic deterioration and the strengthening of the East Asian summer monsoon after about 3-4 Ma. (c) 2006 Elsevier B.V. All rights reserved.

Radioactivity Concentrations in Soils in the Qingdao Area, China

The specific activity concentrations of radionuclides U-238, Th-212, and K-40 of 2300 sampling points in the Qingdao area were measured by an FD-3022 gamma-ray spectrometer. The radioactivity concentrations of U-238, Th-232, and K-40 ranged from 3.3 to 185.3, from 6.9 to 157.2, and from 15.8 to 7834.4 Bq kg(-1), respectively. The air-absorbed dose at I meter above ground, effective annual dose, external hazard index, and radium equivalent activity were also calculated to systematically evaluate the radiological hazards of the natural radioactivity in Qingdao. The air-absorbed dose, effective annual dose, external hazard index, and radium equivalent activity in the study area were 98.6 nGy h(-1), 0.12 mSv, 0.56, 197 Bq kg(-1), respectively. Compared with the worldwide value, the air-absorbed dose is slightly high, but the other factors are all lower than the recommended value. The natural external exposure will not pose significant radiological threat to the population. In conclusion, the Qingdao area is safe with regard to the radiological level and suitable for living.

Crystal structure of (5R,10R)-2,7-dibromo-3,8-dihydroxy-5,10-dimethoxy-5,10-dihydrochromeno[5,4,3-cde]chromene sesquihydrate, C16H12Br2O6 center dot 1.5H(2)O

C16H15Br2O7.5, orthorhombic, P2(1)2(1)2 (no. 18), a = 18.483(2) angstrom, b = 9.413(1) angstrom, c = 10.072(1) angstrom, V = 1752.3 angstrom(3), Z = 4, R-gt(F) = 0.083, wR(ref)(F-2) = 0.202, T= 293 K.

Unprecedented 5,5-connected (4(7)center dot 6(3)) (4(8)center dot 6(2)) structural topology: A lead biphosphonate with double layered structure

A new lead(II) phosphonate, Pb[(PO3)(2)C(OH)CH3]center dot H2O (1) was hydrothermally synthesized and characterized by IR, elemental analysis, UV, TGA, SEM, and single crystal X-ray diffraction analysis. X-ray crystallographic study showed that complex 1 has a two-dimensional double layered hybrid structure containing interconnected 4- and 12-membered rings and shows an unusual (5,5)-connected (4(7) . 6(3)) (4(8) .6(2)) topology. (C) 2008 Elsevier B.V. All rights reserved.

优质春小麦新品种高原314的性状表现及推广前景

高原314春小麦新品种在青海省乐都县川水地区突出表现为产量高、品质优、落黄好,可以作为现有水地春小麦替代品种大面积推广应用.