共查询到20条相似文献,搜索用时 46 毫秒
1.
Jrg Dalluhn Hans‐Heinrich Prhl Axel K. Fischer Peter G. Jones Armand Blaschette 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1109-1111
The prominent features in the molecular structure of the title compound (alternative name: 2‐diethylcarbamoyl‐1,1,3,3‐tetraoxo‐1,3,2‐benzodithiazole), C11H14N2O5S2, arise in the urea moiety S2N—C(O)—N′C2: the sum of the angles at N is 332.3 (1)°, the N—C(O)—N′C2 unit is planar, and distances N—C(O) = 1.494 (3) Å, N′—C(O) = 1.325 (2) Å and C—O = 1.215 (2) Å. The molecules are associated via five C—H?O hydrogen bonds to form layers parallel to the yz plane. This compound and its dimethyl homologue, which were synthesized by treating the silver salt of o‐benzenedisulfonimide with carbamoyl chlorides, are prone to rapid hydrolysis at the weak N—C(O) bond. For both molecules, the rotational barrier about the partial N′—C(O) double bond is ca 50 kJ mol?1 at 250 K (from dynamic 1H NMR experiments). 相似文献
2.
Ten years from Glenn T. Seaborg’s death we remember his achievements; his teaching about the importance of basic research
is as timely as ever. 相似文献
3.
The structure changes and the degree of reduction of U3O8 after mechanoactivation in agate and stainless steel vessels in different media are studied. Clearly expressed reduction
of U(IV, VI) oxide, accompanied by oxygen release as a result of mechanochemical activation is observed. The highest degree
of reduction is reached when mechanoactivation is performed in suspension with nonpolar organic solvents. The presence of
acetaldehyde as a reducing agent did not cause valuable increase of the reduction process. Quantitative evaluation of the
mechanochemically induced changes in the crystal structure of U3O8 is done. Decrease of the crystallite sizes of both the U3O8 and the reduced form, provoked by the mechanochemical treatment is observed for all the samples. No other uranium-contained
compounds, formed during the mechanoactivation in the different media and mixtures were found. 相似文献
4.
5.
6.
7.
8.
Automatized Parameterization of the Density‐functional Tight‐binding Method. II. Two‐center Integrals 下载免费PDF全文
Henryk A. Witek Chien‐Pin Chou Grzegorz Mazur Yoshifumi Nishimura Stephan Irle Bálint Aradi Thomas Frauenheim Keiji Morokuma 《中国化学会会志》2016,63(1):57-68
We present an efficient numerical integration scheme (TWOCENT) to be used in the context of automatized parameterization of the density‐functional tight‐binding (DFTB) method. The accuracy of the integration process is assessed and its range of applicability is discussed. The functionality of the developed code is tested by reproducing the electronic portion of the existing mio parameter sets and by reproducing a series of reference DFT band structures of elemental solids. 相似文献
9.
10.
A synthesis of the novel C10H16 hydrocarbon 1,7-trimethylenenorbornane ( 13 ), one of the 19 members of the adamantane family, is described. 相似文献
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Deepak Kumar Semwal Ruchi Badoni Semwal Gurjaspreet Singh 《Helvetica chimica acta》2013,96(3):520-524
The novel androstane‐type steroidal glycoside 1 was isolated from the roots of Asparagus curillus Buch .‐Ham . ex Roxb . Its structure was elucidated as (2α,3β,5α,17β)‐17‐(1‐methoxyethoxy)‐17‐methylandrostane‐2,3‐diol 3‐(β‐D ‐digitoxopyranoside) by means of chemical and advanced spectral analysis. 相似文献