乙烯酮自由基(HCCO·)与二氧化氮(NO2)反应势能面的理论研究

在CCSD(T)/6-311G(d,p)//MP2/6-311G(d,p)+ZPE水平上对反应HCCO+NO2进行了计算, 建立了反应势能面. 此反应由反应物通过三步反应到达产物. 首先, NO2的O原子进攻HCCO自由基中与H相邻的C原子, 形成异构体1[ONOC(H)CO]或2[H(CONOC)O]. 然后, 异构体1和2通过N-O键的断裂形成产物NO和OC(H)CO. 最后, 产物中的OC(H)CO可以通过C-C键的断裂进一步分解为HCO和CO. 由HCCO+NO2反应得到产物NO+HCO+CO.     

NOx/CO2/H2O在BaO(001)表面吸附的理论研究

采用密度泛函理论(DFT)研究了NOx/CO2/H2O在BaO(001)表面不同覆盖度下的吸附情况.计算表明NO以N端吸附在表面氧位,形成NO22-吸附物种;CO2以C端吸附在表面氧位,形成表面CO32-;而H2O在表面发生解离吸附,导致BaO表面的羟基化.NO2有两种主要的吸附模式:以N端吸附在表面氧位,或以O端吸附表面Ba位.各物种在表面的吸附顺序为:NO≈H2O相似文献   

SO_2对NO催化氧化过程的影响 Ⅴ.NiO/γAl_2O_3上SO_2的作用机理

采用程序升温脱附 (TPD)及漫反射原位红外光谱 (DRIFT)技术分析比较了SO2 存在前后 ,NO O2 反应气体在NiO/γ Al2 O3 催化剂上所形成吸附物种的变化情况 ,发现SO2 能促使硝酸盐物种在低温分解并释放出NO2 ,而且耐热稳定的硝酸盐物种也比单纯NO O2 吸附时多 .室温时催化剂表面上的SO2 以弱吸附物种为主 ,特征红外吸收峰位于 13 2 4cm-1附近 ,温度升高后表面硫酸盐物种数量增多 .关联SO2 气氛中NO2 的生成规律后得出 ,类似于铅室反应中间体的多分子吸附物种[NO2 (SO3 ) x]是产生NO2 的活性物种 ,由SO2 在载体或催化剂表面弱碱位吸附后吸引气相NO所产生 ,解离O-起到稳定活性物种和补充弱碱位的作用 .同时该物种也是毒性物质SO2 -4的前驱体 ,当NO氧化反应发生后催化剂的失活也开始了 .     

介质阻挡放电引发氮氧化物等离子体化学反应

在523 K介质阻挡放电条件下,研究了不同气体组分体系中NO的转化.实验表明,在无氧体系(NO/N2)中,转化的NO主要分解为N2和O2.在富氧(NO/O2/N2)条件下,由于NO和NO2的生成, NO的转化率最低.体系中加入C2H4(NO/C2H4/N2)时, NO转化率与NO/N2体系几乎一样,与NO相比,生成的O更易与C2H4作用,几乎没有NO2的生成.当C2H4和O2共存时(NO/O2/C2H4/N2),NO主要被氧化为NO2.当能量密度为125 J•L－1时, 与其它体系相比,NO/O2/C2H4/N2体系中NO转化率和NO2生成量最大,转化每个 NO分子能耗最小(61 eV).体系中C2H4主要被氧化为CO.四个体系中N2O的生成量都较少.讨论了介质阻挡放电条件下上述四个体系可能的反应机制.     

预吸附氧对NO在Pt(110)表面吸附和分解的影响

 利用程序升温反应谱、X射线光电子能谱和高分辨电子能量损失谱研究了NO在清洁和预吸附氧的Pt(110)表面的吸附和分解. 在清洁的Pt(110)表面,室温下低覆盖度时NO以桥式吸附为主,高覆盖度时NO以线式吸附为主. 加热过程中部分NO(主要是桥式吸附物种)分解,生成N2和N2O. 室温下O2在Pt(110)表面发生解离吸附. Pt(110)表面预吸附氧会抑制桥式吸附NO的生成,并导致其脱附温度降低40 K. 降低脱附温度有利于桥式吸附NO的分子脱附,从而抑制分解反应. 这些结果从表面化学的角度合理地解释了铂催化剂在富氧条件下对NO分解能力的降低.     

N2在含氧Mo(100)表面上的热稳定性

近年来,氮化钼作为催化新材料引起了人们的广泛兴趣.Bafrali等[1,2]在超高真空体系中制备了Mo(100)-c(2×2)N模型表面,并应用热脱附谱(TDS)研究其加氢脱氮等催化性质.他们指出,NH3分解生成的氮原子Nads与Mo(100)-c(2×2)N表面结合牢固,Nads化合形成的N2在1 200 K以上从表面脱附.最近,朱俊发等[3,4]也成功地制备了Mo(100)-c(2×2)N表面,并研究了CO和15NO分子在其上的吸附和反应.他们在研究氮在含氧Mo(100)面上的吸附时发现,吸附了氮的表面经1 100 K退火后形成了有序的c(2×2)N表面结构[5].这些工作各自描述了Mo(100)-c(2×2)N模型表面的制备条件,所需氮的暴露量相差很大.本文在前人工作的基础上,应用俄歇电子能谱(AES)、低能电子衍射(LEED)和热脱附谱等表面分析手段研究了含氧Mo(100)单晶的氮化过程.     

CO为还原剂同时还原SO2和NO的SnO2-TiO2固溶体催化剂Ⅲ.催化剂的活性位和反应机理

 采用显微红外光谱、漫反射红外光谱、瞬变应答反应以及催化剂活性测试等实验手段,对SnO2-TiO2催化剂上SO2+CO,NO+CO和SO2+NO+CO (SRSN)反应的机理及活性位进行了综合研究. 结果表明, SO2+CO和NO+CO反应按典型的Redox机理进行,催化剂的表面晶格氧[O]和氧阴离子空穴[□]([O]-[□])是Redox反应的活性位. 对于SO2+CO反应,其[O]-[□]位于SnO2-TiO2催化剂中邻近Sn离子和邻近Ti离子的位置,邻近Ti离子的[O]-[□]的活性比邻近Sn离子的[O]-[□]的活性高. NO+CO反应主要在邻近Sn离子的[O]-[□]中心上进行. 对于SRSN反应,其中的SO2+CO反应的机理及催化剂的活性位与单纯的SO2+CO反应相同,而其中的NO＋CO反应按两种机理进行: 一种和单纯的NO＋CO反应相同,即按一般的Redox机理进行,其活性位为邻近Sn离子的[O]-[□]中心; 另一种按SO2促Redox反应机理进行,其活性位为表面活性硫物种[SO]*.     

在Rh(111)面上NO+CO反应机理的密度泛函理论研究

应用基于密度泛函理论赝势平面波方法的CASTEP程序, 对Rh(111)上的NO+CO反应机理进行研究. 对于反应中的各个关键步骤: NO离解、CO2生成、通过N2O离解生成N2以及通过N+N反应生成N2都进行了详细讨论, 计算得到各反应步骤的过渡态以及活化能, 从而确立了各步骤的反应路径.     

新型五齿Schiff碱为敏感载体的铅(Ⅱ)离子电极的电位响应行为

以含N和O受体原子的新型五齿Schiff碱(HL)为敏感载体成功构建了高选择性铅(Ⅱ)离子电极.实验结果表明,电极在Pb(NO3)2溶液和部分非水介质中对铅(Ⅱ)离子具有选择性电位识别并呈现近Nernst线性响应.在浓度为1.0×10-1～1.5×10-5 mol/L的Pb(NO3)2溶液中,电极响应斜率为31.4 m...     

[Mn3O(O2CC6H5)6(C3H4N2)3]·C6H5CO2·0.5H2O的 合成、晶体结构及磁性质

Mn(O2CMe)2·4H2O、咪唑、苯甲酸和N(n-Bu)4MnO4在无水乙醇溶剂中反应,制备得到锰的三核μ3-O桥联配位化合物[Mn3O(O2CC6H5)6(C3H4N2)3]·C6H5CO2·0.5H2O.该配位化合物的X射线单晶衍射表明,其属于单斜晶系,空间群P21/C,晶胞参数：a=1.52832(19)nm,b=1.9722(2)nm,c=2.1023(3)nm,β=92.597(3)°,Z=4.变温磁化率(5～280K)研究表明,该配位化合物中3个锰离子在低温下存在弱的反铁磁性耦合,交换积分J=-2.34cm^-1。     

A new route to coordination complexes of nitroxyl (HN=O) via insertion reactions of nitrosonium triflate with transition-metal hydrides

Nitrosonium triflate reacts with cold methylene chloride solutions of mer,trans-ReH(CO)3(PPh3)2 (1) with 1,1-insertion of NO+ into the Re-H bond to give the orange nitroxyl complex [mer,trans-Re(NH=O)(CO)3(PPh3)2][SO3CF3] (3) in 86% isolated yield. Use of [NO][PF6] or [NO][BF4] gives analogous insertion products at low temperature, which decompose on warning to ambient temperature to the fluoride complex mer,trans-ReF(CO)3(PPh3)2 (4). A related 1,1-insertion is observed in the reaction of 1 with [PhN2][PF6] in acetone that affords the yellow-orange phenyldiazene salt [mer,trans-Re(NH=NPh)(CO)3(PPh3)2][PF6] (2), which has been characterized by X-ray crystallographic methods. The methyl derivative mer,trans-Re(CH3)(CO)3(PPh3)2 (5) also undergoes a 1,1-insertion reaction with [NO][SO3CF3] to give the nitrosomethane adduct [mer,trans-Re{N(CH3)=O}(CO)3(PPh3)2][SO3CF3] (6) as red crystals in 75% yield. The nitroxyl complex [cis,trans-OsBr(NH=O)(CO)2(PPh3)2][SO3CF3] (8) can be similarly prepared as orange crystals in 52% yield by reaction of cis,trans-OsHBr(CO)2(PPh3)2 (7) with [NO][SO3CF3] in cold methylene chloride solution.     

Influence of pH and counteranion on the structure of tropolonato-lead(II) complexes: structural and infrared characterization of formed lead compounds

Reactions of tropolone with lead(II) trifluoromethanesulfonate, perchlorate, and nitrate in water/methanol mixtures at pH below 1.0 lead to the formation of three different polymeric lead(II) complexes, [Pb(trop)(CF3SO3)(H2O)]n (1), [Pb3(trop)4(ClO4)2]n (2), and [Pb2(trop)2(NO3)2(CH3OH)]n (3), respectively. On the other hand, if the reactions are performed at pH above 2.0, the dimeric compound [Pb(trop)2]2 (4) is obtained independently of the lead(II) salt used, as long as lead(II) does not form any strong complexes with the counterion. The crystal structures of these compounds have been determined by single-crystal X-ray diffraction. The structure of solid tetrakis(tropolonato)lead(IV), Pb(trop)4 (5), has been studied by means of the EXAFS technique because it was not possible to obtain sufficiently large single crystals. In the polymeric structures, the counterions are coordinated to the lead(II) ions and act as bridges. The tropolonato ligand behaves as a chelating agent and a tri- or tetraconnective bridge. The total coordination number of the lead(II) ion is five in compound 4, seven in 1 and 3, and eight in 2, and the lead(IV) ion in 5 is eight-coordinated. The 6s2 lone electron pair on the lead(II) ion seems to be stereochemically active in all lead(II) complexes studied. All compounds have been characterized by IR spectroscopy as well.     

Lead hydro sodalite [Pb2(OH)(H2O)3]2[Al3Si3O12]2: synthesis and structure determination by combining X-ray rietveld refinement, 1H MAS NMR FTIR and XANES spectroscopy

Ion exchange of the sodium hydro sodalites [Na3(H2O)4]2-[Al3Si3O12]2 [Na4(H3O2)]2[Al3Si3O12]2 and [Na4(OH)]2[Al3Si3O12]2 with aqueous Pb(NO3)2 solutions yielded, whichever reactant sodalite phase was used, the same lead hydro sodalite, [Pb2(OH)-(H2O)3]2[Al3Si3O12]2. Thus, in the case of the non-basic reactant [Na3(H2O)4]2-[Al3Si3O12]2 an overexchange occurs with respect to the number of nonframework cationic charges. Rietveld structure refinement of the lead hydro sodalite based on powder X-ray diffraction data (cubic, a = 9.070 A, room temperature, space group P43n) revealed that the two lead cations within each polyhedral sodalite cage form an orientationally disordered dinuclear [Pb2(micro-OH)(micro-H2O)(H2O)2]3+ complex. Due to additional lead framework oxygen bonds the coordination environment of each metal cation (CN 3+3) is approximately spherical, and clearly the lead 6s electron lone pair is stereochemically inactive. This is also suggested by the absence of a small peak at 13.025 keV, attributed in other Pb2+-O compounds to an electronic 2p-6s transition, in the PbL3 edge XANES spectrum. 1H MAS NMR and FTIR spectra show that the hydrogen atoms of the aqua hydroxo complex (which could not be determined in the Rietveld analysis) are involved in hydrogen bonds of various strengths.     

Holo- and hemidirected lead(II) in the polymeric [Pb(4)(mu-3,4-TDTA)2(H2O)2]*4H2O complex. N,N,N',N'-tetraacetate ligands derived from o-phenylenediamines as sequestering agents for lead(II)

The coordinating ability of the ligands 3,4-toluenediamine-N,N,N',N'-tetraacetate (3,4-TDTA), o-phenylenediamine-N,N,N',N'-tetraacetate (o-PhDTA), and 4-chloro-1,2-phenylenediamine-N,N,N',N'-tetraacetate (4-Cl-o-PhDTA) (H4L acids) toward lead(II) is studied by potentiometry (25 degrees C, I = 0.5 mol x dm(-3) in NaClO4), UV-vis spectrophotometry, and 207Pb NMR spectrometry. The stability constants of the complex species formed were determined. X-ray diffraction structural analysis of the complex [Pb4(mu-3,4-TDTA)4(H2O)2]*4H2O (1) revealed that 1 has a 2-D structure. The layers are built up by the polymerization of centrosymmetric [Pb4L2(H2O)2] tetranuclear units. The neutral layers have the aromatic rings of the ligands pointing to the periphery, whereas the metallic ions are located in the central part of the layers. In compound 1, two types of six-coordinate lead(II) environments are produced. The Pb(1) is coordinated to two nitrogen atoms and four carboxylate oxygens from the ligand, whereas Pb(2) has an O6 trigonally distorted octahedral surrounding. The lead(II) ion is surrounded by five carboxylate oxygens and a water molecule. The carboxylate oxygens belong to four different ligands that are also joined to four other Pb(1) ions. The selective uptake of lead(II) was analyzed by means of chemical speciation diagrams as well as the so-called conditional or effective formation constants K(Pb)eff. The results indicate that, in competition with other ligands that are strong complexing agents for lead(II), our ligands are better sequestering agents in acidic media.     

Structure and multinuclear solid-state NMR of a highly birefringent lead-gold cyanide coordination polymer

The coordination polymer Pb(H2O)[Au(CN)2]2 (1) was synthesized by the reaction of KAu(CN)2 and Pb(NO3)2. The structure contains 1-D chains of lead(II)-OH2 linked via Au(CN)2(-) moieties, generating a 2-D slab; weak aurophilic interactions of 3.506(2) and 3.4885(5) A occur within and between slabs. The geometry about each lead(II) is bicapped trigonal prismatic, having six N-bound cyanides at the prism vertices and waters at two of the faces. Dehydration at 175 degrees C yields microcrystalline Pb[Au(CN)2]2 (2), which, along with 1, was examined by 13C, 15N, 1H, and 207Pb solid-state NMR methods. Two 15N resonances are assigned to the mu2-bridging and hydrogen-bonding cyanides in 1. Upon dehydration, the 207Pb NMR spectrum becomes axially symmetric and yields a reduced shielding span, indicating higher site symmetry, while the 13C and 15N spectra reveal a single cyanide. Although no single-crystal X-ray structure of 2 could be obtained, a structure is proposed on the basis of the NMR and X-ray powder data, consisting of a lead(II) center in a distorted square-prismatic environment, with cyanides present at each corner. The birefringence of single crystals of 1 is found to be 7.0 x 10(-2) at room temperature. This value is large compared to that of most optical materials and can be attributed to the anisotropy of the 2-D slabs of 1, with all CN bonds aligned in the same direction by the polarizable lead(II) center.     

Permetalloplumbanes: Preparation of [Pb{Co(CO)3(L)}4] and [Pb{Fe(CO)2(NO)(L)}4].: Complexes containing four transition metal to lead bonds (L = tertiary arsine,phosphine or phosphite).

The sole and unexpected products from the reactions of a variety of lead (II) and lead (IV) compounds with [Co₂(CO)₆(L)₂] complexes (L = tertiary arsine, phosphine, or phosphite) in refluxing benzene solution are the blue, air-stable percobaltoplumbanes [Pb{Co(CO)₃(L)}₄]. These have also been obtained from the reaction of Na[Co(CO)₃(L)] (L  PBu₃ⁿ) with lead (II) acetate which with Na[Fe(CO)₂(NO)(L)] forms the isoelectronic [Pb{Fe(CO)₂(NO)(L)}₄] [L  P(OPh)₃]. The IR spectra of the complexes in the v(CO) and v(NO) regions are consistent with tetrahedral PbCo₄ or PbFe₄ fragments, trigonal bipyramidal coordination about the cobalt or iron atoms and linear PbCoAs, PbCoP, or PbFeP systems. Unlike [Pb{Co(CO)₄}₄], our complexes do not dissociate to [Co(CO)₃(L)]^? or [Fe(CO)₂(NO)(L)]^? ions when dissolved in donor solvents.     

PEO-[M(CN)5NO](x-) (M = Fe, Mn, or Cr) interaction as a driving force in the partitioning of the pentacyanonitrosylmetallate anion in ATPS: strong effect of the central atom

The partitioning behavior of pentacyanonitrosilmetallate complexes[Fe(CN) 5NO] (2-), [Mn(CN) 5NO] (3-), and [Cr(CN) 5NO] (3-)has been studied in aqueous two-phase systems (ATPS) formed by adding poly(ethylene oxide) (PEO; 4000 g mol (-1)) to an aqueous salt solution (Li 2SO 4, Na 2SO 4, CuSO 4, or ZnSO 4). The complexes partition coefficients ( K complex) in each of these ATPS have been determined as a function of increasing tie-line length (TLL) and temperature. Unlike the partition behavior of most ions, [Fe(CN) 5NO] (2-) and [Mn(CN) 5NO] (3-) anions are concentrated in the polymer-rich phase with K values depending on the nature of the central atom as follows: K [ F e ( C N ) 5 N O ] 2 - > K [ M n ( C N ) 5 N O ] 3 - > K [ C r ( C N ) 5 N O ] 3 - . The effect of ATPS salts in the complex partitioning behavior has also been verified following the order Li 2SO 4 > Na 2SO 4 > ZnSO 4. Thermodynamic analysis revealed that the presence of anions in the polymer-rich phase is caused by an EO-[M(CN) 5NO] ( x- ) (M = Fe, Mn, or Cr) enthalpic interaction. However, when this enthalpic interaction is weak, as in the case of the [Cr(CN) 5NO] (3-) anion ( K [ C r ( C N ) 5 N O ] 3 - < 1), entropic driving forces dominate the transfer process, then causing the anions to concentrate in the salt-rich phase.     

A complex of ceftriaxone with Pb(II): synthesis,characterization, and antibacterial activity study

A Pb(II) complex with ceftriaxone (H₂Ceftria) antibiotic was synthesized by reaction of ceftriaxone disodium salt (hemi)heptahydrate with lead nitrate in water–ethanol medium. The complex was characterized on the basis of complexometric titration, spectrophotometric and thermogravimetric analyses, capillary electrophoresis, IR, Raman and UV–vis spectroscopies, and density functional theory calculations. Pb(II) is five-coordinate with distorted square pyramidal geometry. The coordination of Ceftria^2? to Pb(II) occurs through N and O of the triazine, lactam carbonyl, carboxylate, and amine groups. The antibacterial activity study showed that Klebsiella pneumoniae is resistant to [Pb(Ceftria)]·3H₂O. The antibacterial activity of [Pb(Ceftria)]·3H₂O against Staphylococcus aureus is reduced compared with ceftriaxone. In contrast, the antibacterial activity of [Pb(Ceftria)]·3H₂O against Escherichia coli is 28% higher than that of ceftriaxone antibiotic.     

钛铝载体的合成及负载CuO对NO催化性能研究

以TiCl4为原料合成了TiO2/[[alpha]]-Al2O3载体. 在色谱-微反流动法反应装置上考察了CuO/15%(w, 下同)TiO2/[alpha]-Al2O3系列催化剂对NO+CO 的反应性能. 结果表明上述催化剂对NO+CO 反应表现出较好的活性, 其中12%CuO/15%TiO2/[alpha]-Al2O3反应活性最佳. 空气和H2 预处理后, NO 完全转化的温度分别为300C[[deg]]和275C[deg].通过H2-TPR、XRD 和FT-IR 等技术表征, 发现适量TiO2能促进CuO 在钛铝载体上的分散. TPR 结果显示12%CuO/15%TiO2/[alpha]-Al2O3在整个TPR 过程中出现四个还原峰, 琢和酌还原峰分别是钛铝载体表面裸露的TiO2上高度分散的CuO 和晶相CuO 的还原；茁和啄还原峰为钛铝载体上高度分散的CuO 和晶相CuO 的还原. FT-IR实验表明NO和CO 在经H2气氛预处理的催化剂表面上吸附较强, 且生成了N2O 和NO2等物种；NO+CO混合气在经空气和H2预处理的催化剂表面吸附时, 出现了N2O吸收峰, 峰温分别为200C[deg]和150C[deg].     

Second-sphere interaction of anions with a weakly binding metal complex host: probing the effect of counteranions

The reaction of [Re(OTf)(CO)5] with N-methylimidazole (MeIm) afforded [Re(CO)3(MeIm)3]OTf (1). The reactions of 1 with KPF6, NaBPh4 and NaBAr'4 (Ar' = 3,5-bis(trifluoromethyl)phenyl) afforded [Re(CO)3(MeIm)3]PF6 (2) [Re(CO)3(MeIm)3]BPh4 (3) and [Re(CO)3(MeIm)3]BAr'4 (4) respectively. An analogous reaction using N-phenylimidazole (PhIm) yielded [Re(CO)3(PhIm)3]BAr'4 (7). These new compounds were characterized by IR and NMR, and the structures of 1 and 2 were determined by X-ray diffraction. Compounds [Re(CO)3(MeIm)3]2[PtCl6] (5), [Re(CO)3(MeIm)3][HSO4] (6), [Re(CO)3(PhIm)3][Br] (8) and [Re(CO)3(PhIm)3][NO3] (9) were crystallized from equimolar mixtures of either 4 or 7 and the tetrabutylammonium salt of the corresponding anion, and their structures were determined by X-ray diffraction. The solution behavior of 1-4, 7 toward several anions was studied spectroscopically, including the quantitative determination of binding constants by 1H NMR. The cationic tris(imidazole)complexes are stable against imidazole-by-anion substitution, and the main hydrogen bonding interactions involve the imidazole NC(H)N groups. The binding constants for compounds 1-4 with several external anions follow the order 1<2<3<4, indicating that the strength of the cationic complex-counteranion interaction follows the order OTf(-) > PF6(-) > BPh4(-) > BAr'4(-).