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31.
Rita Kakkar Mallika Pathak Preeti Chadha 《International journal of quantum chemistry》2005,102(2):189-199
The rearrangement of vinylidene to acetylene has been studied in detail by the density functional method, using Becke's three‐parameter exchange functional and the gradient‐corrected functional of Lee, Yang, and Parr. The rearrangement of the anion, as well as that of fluoro‐substituted systems, has also been investigated, in order to determine the effect of fluorine substitution on the activation barrier to the 1,2‐hydrogen shift, as well as the relative migratory aptitudes of hydrogen and fluorine. Natural bond orbital analysis is invoked to gain insight into the mechanisms of the rearrangements. Basis size effects are also discussed, particularly in relation to anionic systems. The need to include diffuse functions in geometry optimizations of anionic systems is reinforced by the present calculations. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
32.
Stability constants of the ternary complexes [CuAL] whereA = 5-Nitro-1,10-phenanthroline, bis(2-pyridyl) ketone (DPK) orbis(2-pyridyl)amine (DPA) andL is the dianion of catechol, tiron, protocatechic acid, pyrogallol, 1,8-dihydroxynaphthalene, catecholaldehyde, 2,3-dihydroxynaphthalene,
dopamine or adrenaline have been determined by potentiometric titration in dioxane water (1:1 v/v) medium using a SCOGS computer
programme. The observed trend of stability is explained on the basis of the nature of substitution over the ligands, chelate
ring size and also the composition of mixed solvent in case of DPK. Structural changes in DPK have also been discussed as
a function of pH, composition of medium and coordinating mode of the secondary ligand in the ternary complexes. 相似文献
33.
Marta Filizola Maria Carteni-Farina Juan J. Perez 《Journal of computer-aided molecular design》1999,13(4):397-407
3D models of the opioid receptors , and were constructed using BUNDLE, an in-house program to build de novo models of G-protein coupled receptors at the atomic level. Once the three opioid receptors were constructed and before any energy refinement, models were assessed for their compatibility with the results available from point-site mutations carried out on these receptors. In a subsequent step, three selective antagonists to each of three receptors (naltrindole, naltrexone and nor-binaltorphamine) were docked onto each of the three receptors and subsequently energy minimized. The nine resulting complexes were checked for their ability to explain known results of structure-activity studies. Once the models were validated, analysis of the distances between different residues of the receptors and the ligands were computed. This analysis permitted us to identify key residues tentatively involved in direct interaction with the ligand. 相似文献
34.
铜基催化剂的结构、物性及其对混合碳四选择加氢反应的催化性能 总被引:2,自引:0,他引:2
用XRD,XPS,SEM和H2-TPR等手段研究了铜基负载型催化剂的结\r\n构和物性及其对混合碳四加氢脱炔的催化性能.结果表明,在负载铜催\r\n化剂中加入一定量的Co可提高催化剂的加氢脱炔活性,而Co含量较少时\r\n加入少量的Ce也能提高催化剂的活性和选择性.Cu和Co之间存在着相互\r\n协同作用,使得活性组分在催化剂表面偏析,CuO在催化剂表面呈非晶\r\n相分散状态,催化剂颗粒粒径变小,催化剂更容易被还原,从而改善了\r\n催化剂的催化性能. 相似文献
35.
Suyun Jie Tianzhu Zhang Jiutong Chen Dongbing Liu Wei Chen 《Journal of organometallic chemistry》2005,690(7):1739-1749
A series of bridged bis(pyridinylimino) ligands were efficiently synthesized through the condensation reaction of 4,4′-methylene-bis(2,6-disubstituted aniline) with 2-pyridinecarboxaldehyde or 2-benzoylpyridine. They reacted with (DME)NiBr2 to form dinuclear Ni(II) complexes. All resultant compounds were characterized by elemental analysis, IR spectra as well as the single-crystal X-ray diffraction to confirm the structures of ligands and complexes. Activated with methylaluminoxane (MAO), these nickel complexes showed considerably good activities for ethylene oligomerization and polymerization. Their catalytic activities and the properties of PEs obtained were depended on the arched environment of ligand and reaction conditions. 相似文献
36.
XU Xing-Youa MA Wei-Xinga GAO Jiana LIU Qing-Liangb a 《结构化学》2002,21(5):473-476
1 INTRODUCTION Macrocyclic ligands and their metal complexes have received much attention due to their applications in ion transport, ion separation and as models in biomimic researches[1~7]. The synthetic methods of macrocyclic ligands and their metal complexes are mainly divided into three kinds[8]. The first one is synthesizing free ligand, then forming the metal complexes; the second is template synthesis; and the third is synthesizing the end-off or side-off precursor ligand, then c… 相似文献
37.
0IntroductionThefirstmolecule鄄basedmagnetswerereportedin1986[1].Duringthelasttwodecades,moreandmoreattentionhasbeenpaidtothesynthesisofmolecule鄄basedmagnets,especiallytoPrussianBlueanalogu鄄es[2].TheoldPrussianBlueanalogueshavebeenbroughtuptodateduetoth… 相似文献
38.
39.
A novel chiral Salen ligand with a glucose moiety was synthesized from the condensation of 1,2:5,6-di-O-isopropylidene-3-O-methylene-[5-(3-tert-butyl-2-hydroxy benzaldehyde)]-α-D-glucofuranose with (1R,2R)-1,2-diaminocyclohexane. Several chiral complexes of Mn3+, Fe3+, Co2+ and Cu2+ were prepared from this ligand. Both the ligand and the complexes were characterized by elemental analysis, NMR, IR, MS, and UV-Vis. 相似文献
40.
若干中性配体对Mo—Fe—S簇合物自兜的影响 总被引:3,自引:1,他引:3
通过电子吸收光谱的变化研究了一些含N和含P中性配体对MoS_4~(2-)-nFeCl_2-DMF体系形成立方烷型Mo-Fe-S簇合物的可能影响。 相似文献