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1.
王崇臣  王鹏 《化学研究》2008,19(4):9-13
用NiCl2·6H2O,2,2'-联吡啶(bpy),NH4VO3,WO3在443K下通过水热反应法得到了两种多钒酸镍配合物Ni(bpy)(H2O)(V2O6)(1)和[Ni(bpy)2]2(V6O17)(2).单晶X射线衍射结果表明化合物(1)属于正交晶系,空间群为Pcα2(1),晶胞参数为0=0.91704(18)nm,b=1.0519(2)nm,c=1.4336(3)nm,V=1.3830(5)nm^3,Z=4;化合物(2)属于单斜晶系,空间群为P2(1)/c,晶胞参数为α=1.5467(3)nm,b=1.4740(3)nm,c=1.0457(2)nm,β=91.99(3)°,V=2.3826(8)nm^3,Z=4.化合物(1)由2,2’-联吡啶修饰的二维[Ni(V2O6)(H2O)]∞电中性层构成,而化合物(2)则由2,2'-联吡啶修饰的、呈正弦波浪状的[Ni:(V6O17)]∞二维电中性层构成.  相似文献   

2.
运用第一性原理计算了锂嵌入对α-V2O5中O2p和V3d轨道电了结构的影响.计算结果表明,不同的锂嵌入位置对O2p和V3d轨道的电了结构有着不同的影响.但锂的嵌入会减弱了V2O5中V=O1键,同时导致V3d导带的劈裂变窄或消失和HO2p价带变宽.最后计算出从每个Li2s轨道到V3d轨道的电子传递数为0.52.  相似文献   

3.
单核Mn(III)-Shiff碱配合物的晶体结构与性质   总被引:1,自引:0,他引:1  
报导了两个Schiff碱配体的单核Mn(Ⅲ)配合物([Mn(Ⅲ)(L1)(H2O)]4CIO。·ZH。O(1)和[Mn(ffi)(LZ)厂Ic。·ZH。O(2》的合成、晶体结构及性反X一衍射晶体结构分析证实:配合物1的晶体属于正交晶系,Pna21空间群.其晶胞参数为α=10.932(7)A,b=22.393(5)A,c=8.960(3)A,V=2193(1)A3,Z=4.2的晶体属于正交晶系,P212121空间群,α=17.345(3)A,b=17.905(2)A,c=7.789(1)A,V=2418.9(6)A3,Z=4.电化学研究结果显示:配合2是稳定的电化学产物,而1在电场作用下容易歧化.由此说明配位环境是影响化合物稳定性的重要因素.  相似文献   

4.
氨再生条件对V2O5/AC同时脱硫脱硝活性的影响   总被引:5,自引:5,他引:5  
对烟气同时脱硫脱硝过程中吸附SO2后的活性炭载V2O5(V2O5/AC)催化 吸附剂在含NH3气氛下的再生条件进行了考察,发现3%~5%NH3/Ar气氛、300℃、60min再生可有效恢复V2O5/AC的脱硫活性,并明显提高其脱硝活性。基于对SO2和NO的脱除率、再生后V2O5/AC的硫质量分数以及FT IR谱图分析发现,NH3的存在对V2O5/AC所吸附硫的脱附行为没有明显影响,但可显著改变V2O5/AC的表面化学性质,有利于烟气脱硫;NH3还可在V2O5/AC表面储存,显著促进脱硝。  相似文献   

5.
正丁烷氧化制顺酐流化床催化剂的性能   总被引:1,自引:0,他引:1  
许文  薛常海 《催化学报》2002,23(3):199-202
 考察了前驱体制备过程中水合肼/五氧化二钒摩尔比(以下简记\r\n为n(N2H4)/n(V2O5))对催化剂性能的影响.由较高的n(N2H4)\r\n/n(V2O5)比制得的催化剂,其(VO)2P2O7相含量较多,正丁烷转化\r\n率较高.随着n(N2H4)/n(V2O5)比的减小,δ-VOPO4相的含量逐\r\n渐增多,正丁烷转化率随之升高;而顺酐选择性开始时升高,达到最大\r\n值后逐渐降低.在n(N2H4)/n(V2O5)=0.34时制备的催化剂最佳\r\n,在丁烷浓度为4.0%、空速为500h-1及反应温度为420℃的反应条件\r\n下,顺酐收率可达49.74%.本文中细粒床催化剂有较大的操作弹性.  相似文献   

6.
Three new inorganic-organic composite polyoxotungstates [Cu(2,2'-bpy)2]5[α-PW11.5Cu0.5O40]·2H2O 1, [Co(2,2'-bpy)2(N3)2]4H3[α-PW12O40]·3H2O 2 and [Cu(2,2'-bpy)2(4,4'-bpy)]2[α-GeW12O40]-4H2O 3 (2,2'-bpy = 2,2'-bipyridine, 4,4'-bpy = 4,4'-bipyridine) have been hydrothermally synthesized and structurally characterized. 1 crystallizes in the orthorhombic space group Pna21 with a = 27.847(3), b = 21.597(2), c = 20.1179(19)A, V= 12099(2)A^3, Z= 4, GOF= 1.038, R = 0.0427 and wR = 0.1035; 2 belongs to the triclinic space group P1^- with a = 12.31150(10), b = 16.1954(4), c = 19.36290(10)A, α = 99.366(11), β =105.168(8), γ = 111.836(8)°, V = 3309.98(9)A3, Z = l, GOF = 1.024, R = 0.0739 and wR = 0.2216; and 3 crystallizes in the monoclinic space group P21/n with a = 12.858(4), b = 20.943(6), c = 15.598(5)A, β = 102.338(5)°, V= 4103(2)A3, Z = 2, GOF = 1.026, R = 0.0557 and wR = 0.1316. The common structural features of 1-3 are that their molecular structures all consist of a saturated a-Keggin polyoxoanion and several discrete metal-organic moieties. Intriguingly, 2 and 3 are composed of metal-organic coordination moieties with two mixed ligands.  相似文献   

7.
采用SCC-DV-Xα方法对α-Keggin结构硅钼二电子还原态杂多蓝阴离子[SiMo2(V)Mo10(VI)O40]6-和它的混合型钒取代物[SiV2(V)Mo10(VI)O40]6-进行了量子化学计算,获得了轨道能级、费米能级、各原子价电子布居、自由价态密度分析和分子轨道成分等信息.理论分析表明该杂多阴离子中所有原子Si、Mo、V、Oa、Ob、Oc和Od都参与反应,Oc和Od的成键能力较强,化学活性较大,有力地支持了实验结果.中心硅氧四面体结构发生畸变很小,但构成三金属簇的八面体结构都发生了较明显的畸变,其整体仍然保持α-Keggin结构.钒的取代增强了Mo2VO13三金属族中Od的活性.预测这两种杂多阴离子都有被继续还原和取代的趋势,[SiMo2(V)Mo10(VI)O40]6-的趋势更强.  相似文献   

8.
李杰  郭静玉 《化学研究》2014,(6):573-578
采用水热法合成了一维锯齿链状的有机-无机杂化杂多钨酸盐[Cu(en)2(H2O)]{[Cu(en)2(H2O)][Cu(en)2](α-SiW12O40)}(OH)2·H2O(记作1;en=1,2-乙二胺);利用元素分析、红外光谱和X射线单晶衍射对其结构进行了表征.结果表明,化合物1属于三斜晶系,P-1空间群;其晶格参数为:a=1.297 6(6)nm,b=1.473 5(7)nm,c=1.909 9(9)nm,α=86.736(8)°,β=88.833(8)°,γ=74.840(8)°,V=3.519(3)nm3,Z=2.就分子结构而言,化合物1由一个常见的Keggin型多阴离子[α-SiW12O40]4-、两个不同的铜配位阳离子[Cu(en)2(H2O)]2+和[Cu(en)2]2+、一个游离的铜配位阳离子[Cu(en)2(H2O)]2+、两个氢氧根离子和一个结晶水组成;相邻的[α-SiW12O40]4-多阴离子通过两个配位阳离子[Cu(en)2)]2+相连,形成一维锯齿链状结构.  相似文献   

9.
采用燃烧法制备出Li^+,Zn^2+掺杂的Gd2O3:Eu^3+纳米荧光粉,研究了掺杂离子对Gd2O3:Eu^3+的结晶性能、晶粒形貌和光致发光特性的影响.以X射线衍射(XRD)、透射电子显微镜(TEM)、发射光谱和衰减时间谱等手段表征材料性能.结果表明,Li^+,Zn^2+掺杂可显著提高Gd2O3:Eu^3+纳米粉在611 nm处的发光强度,最大可达到未掺杂时的2.5倍.发光增强的主要原因可归结为3个方面: (1)使晶粒由单斜相向更利于发光的立方相转变; (2)氧空位的敏化剂作用; (3)掺杂离子的助熔剂效应,使晶粒的结晶性能提高、粒径增大,从而降低表面态引起的发光猝灭.  相似文献   

10.
以CO(NO3)2,2,2'-联吡啶(2,2'-bipy)及NaVO3为原料,采用水热法于200℃合成了一种新的有机.无机杂化材料——Co(2,2'-bipy)(H2O)V2O6(1),其结构经IR,热重分析及X-射线单晶衍射表征。结果表明,1属于单钭晶系,空间群为P21/c,晶胞参数为:a=7.8556(3)A,b=21.0562(5)A,c=9.5521(6)A,a=90.000^o,β=110.236(5)^o,y=90.000^o,V=1423.65(8)A^3,Z=2,Dc=2.126g·cm^-3,μ(MoKα)=2.548mm^-1,R1=0.0586,wR2:0.0935。1为一种二维层状结构,由[VO4]四面体通过共顶点构成的一维钒氧链,链与链之间以[Co(2,2'-bipy)(H2O)]^2+基团连接而成。  相似文献   

11.
用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.  相似文献   

12.
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.  相似文献   

13.
The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.  相似文献   

14.
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.  相似文献   

15.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.  相似文献   

16.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

17.
Zhanhui Yang  Shiyi Yang  Jiaxi Xu 《Tetrahedron》2017,73(23):3240-3248
Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.  相似文献   

18.
19.
《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.  相似文献   

20.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.  相似文献   

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