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41.
In order to study the effects of R group on Fe–Hg interactions and 31P chemical shifts, the structures of mononuclear complexes Fe(CO)3(PPh2R)2 (R=pym:1, fur: 2, py: 3,thi: 4; pym=pyrimidine, fur=furyl, py=pyridine, thi=thiazole) and binuclear complexes [Fe(CO)3(PPh2R)2(HgCl2)] (R=pym: 5, fur: 6, py: 7, thi: 8) were studied using the density functional theory (DFT) PBE0 method. The 31P chemical shifts were calculated by PBE0-GIAO method. Nature bond orbital (NBO) analyses were also performed to explain the nature of the Fe–Hg interactions. The conclusions can be drawn as follows: (1) The complexes with nitrogen donor atoms are more stable than those with O or S atoms. The more N atoms there are, the higher is the stabilility of the complex. (2) The Fe–Hg interactions play a dominant role in the stabilities of the complexes. In 5 or 6, thereisa σ-bond between Fe and Hg atoms. However, in 7 and 8, the Fe–Hg interactions act as σP–Fe→nHg and σC–Fe→nHg delocalization. (3) Through Fe→Hg interactions, there is charge transfer from R groups towards the P, Fe, and Hg atoms, which increases the electron density on P nucleus in binuclear complexes. As a result, compared with their mononuclear complexes, the 31P chemical shifts in binuclear complexes show some reduction. 相似文献
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AbstractA simple, efficient, and metal-free methodology for the preparation of 2-mercaptobenzothiazole and derivatives in excellent yields via microwave-assisted pathway is reported. Our condition provides a convenient protocol for the synthesis of a diverse collection of 2-mercaptobenzothiazoles and 6-(4-substituted-1H-1,2,3-triazol-1-yl)-2-mercaptobenzothiazoles with a very simple purification process. This report provides an alternative protocol for fast access to the wide range of compounds for sequence synthesis and biological studies. 相似文献
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Jun Zhou Jie Yang Li Qi Xuan Shen Dunru Zhu Yan Xu You Song 《Transition Metal Chemistry》2007,32(6):711-715
A novel dinuclear nickel(II) complex, [Ni2(MOBPT)2Cl2(H2O)2]Cl2 · 7H2O (MOBPT = 4-(p-methoxyphenyl) −3,5-bis(pyridine-2-yl)-1,2,4-triazole), has been synthesized and characterized by elemental analysis, IR and single crystal X-ray
diffraction methods. The crystal structure determination shows that the dinuclear Ni2N8 unit is almost planer in which each NiII ion is coordinated by four nitrogen atoms from MOBPT equatorially and a water molecule and a chloride ion axially in a distorted
octahedral geometry. Magnetic measurements reveal a relatively weak antiferromagnetic exchange in the complex. 相似文献
47.
Peng Yang Xuan Wang Bo Li Yixuan Yang Jinfeng Yue Yanrui Suo Huarong Tong Gang He Xiaojie Lu Gong Chen 《Chemical science》2021,12(16):5804
A highly efficient and versatile method for construction of peptide macrocycles via palladium-catalyzed intramolecular S-arylation of alkyl and aryl thiols with aryl iodides under mild conditions is developed. The method exhibits a broad substrate scope for thiols, aryl iodides and amino acid units. Peptide macrocycles of a wide range of size and composition can be readily assembled in high yield from various easily accessible building blocks. This method has been successfully employed to prepare an 8-million-membered tetrameric cyclic peptide DNA-encoded library (DEL). Preliminary screening of the DEL library against protein p300 identified compounds with single digit micromolar inhibition activity.A highly efficient and versatile method for construction of peptide macrocycles via palladium-catalyzed intramolecular S-arylation of alkyl and aryl thiols with aryl iodides under mild conditions is developed. 相似文献
48.
C. Decker H. Le Xuan T. Nguyen Thi Viet 《Journal of polymer science. Part A, Polymer chemistry》1995,33(16):2759-2772
Low molecular weight epoxidized natural rubber has been crosslinked within seconds by UV irradiation in the presence of a triarylsulfonium salt. The photoinitiated cationic ring-opening polymerization was studied quantitatively by infrared spectroscopy and shown to proceed with surprisingly long kinetic chains in such solid medium. The high conversion (60%) needed for complete insolubilization, together with the presence of tetrahydrofuran structures, argue in favor of an intramolecular polymerization process involving neighboring epoxy groups. The photoinitiator concentration has a strong influence on the rate and extent of the reaction, as well as on the depth of cure profile. Because of an efficient dark process, close to 100% conversion was reached upon storage of the irradiated elastomer at ambient, with a concomitant increase of the gel fraction and the polymer hardness. The grafting of pendent acrylate groups onto the polymer chain leads to a three-fold decrease of the initial rate of polymerization of the epoxide. The photocuring of natural rubber bearing both epoxy and acrylate groups generates a dual polymer network which combines the properties of the two moieties. © 1995 John Wiley & Sons, Inc. 相似文献
49.
Ying-nan Xuan Yan Gao Yong Huang Xi-gao Jian Laboratory of Cellulose Lignocellulosics Chemistry Guangzhou Institute of Chemistry Chinese Academy of Sciences Guangzhou China Institute of Chemistry Chinese Academy of Sciences Beijing China Department of Polymer Science College of Chemical Engineering Dalian University of Technology Dalian China 《高分子科学》2002,(3):225-229
A kind of novel heat-resistant, high performance engineering thermoplastic phthalazinone poly(aryl ether sulfoneketone) (PPESK) containing a carboxyl group in its side chain was prepared by the nucleophilic displacement reaction of 4-(4-hydroxylphenyl)-1(2H)-phthalazinone with di(4-chlorophenyl) sulfone, 4,4'-difluoro-benzophenone and phenolphthalin insulfolane in the presence of K_2CO_3 to produce high molecular weight polymers which can be dissolved in some polarsolvents such as chloroform and nitrobenzene at room temperature and can be easily can into flexible, yellowish andtransparent films. PPESK is an amorphous polymer having a decomposition temperature above 400℃, which indicates that ithas high thermal stability. At the same time, the thermal properties of PPESKs with dicyandiamide (DICY) as curing agentindicated that the heat-resistance properties of the PPESKs are improved after curing. The apparent activation energy (ΔE) ofthe cross-linking reaction and the reaction order (n) of PPESK/DICY were found to be 52.2 kJ/mol and ca. 1.0, respectively.Therefore, the cross-linking reaction is approximately a first order reaction. 相似文献
50.
用原子吸收光谱法测定延边地区317名65~108岁老人头发中锌、铜、铁、锰、镁含量,观察不同民族、性别、年龄老人这些元素的差异。结果表明:1.朝鲜旗发锌低于汉族,满族发铜低于汉族、朝鲜族,汉族发镁高于朝鲜族、满族,发铁、发锰在汉、朝、满民族之间无区别。2.汉族、朝鲜族男发锌高于女性,汉族女性发铜高于男性,发铁、发锰、发镁在性别之间无区别。3、90岁组朝鲜族发锰、发镁低于65岁、76岁组,朝鲜族发锌、发铜、发铁在65~108岁之间无统计学意义。 相似文献