Isotopic exchange reactions between iron-sulphur-nitrosyl clusters and nitrite

The anion [Fe₄S₃(NO)₇]⁻ undergoes slow exchange with labelled nitrite [¹⁵NO₂]⁻ to yield a product [Fe₄S₃(¹⁴NO)(¹⁵NO)₆]⁻ in which complete isotopic exchange has occurred at the basal Fe(NO)₂ groups, but with no exchange at the apical Fe(NO) group. The neutral Fe₄S₄(NO)₄ reacts rapidly with [¹⁵NO₂⁻ to give fully exchanged [Fe₄S₃(¹⁵NO)₇]⁻, and it is proposed that the conversion proceeds by fragmentation, followed by complete isotopic exchange and rapid reassembly. The binuclear anion [Fe₂S₂(NO)₄]²⁻ also yields, with [¹⁵NO₂]²⁻ in CD₂Cl₂ solution, the fully exchanged [Fe₄S₃(¹⁵NO)₇]⁻, and a mechanism involving successive fragmentation, exchange and reassembly steps is proposed; however in aqueous solution, a clean exchange reaction occurs to give [Fe₂S₂(¹⁵NO)₄]²⁻. Neutral binuclear esters Fe₂(SR)₂(NO)₄ (R = Me, Et, or Ph) with [¹⁴NO₂]⁻ yield the mononuclear paramagnetic [Fe(¹⁴NO)₂(¹⁴NO₂)₂]⁻, and with [¹⁵NO₂]⁻ the analogous [Fe(¹⁵NO)₂(₁₅NO₂)₂]⁻.     

1,3-丙二胺邻苯二酚钼钨手性八面体配合物的仿生合成、晶体结构以及与ATP作用的液相NMR研究

合成了1,3-丙二胺邻苯二酚钼钨手性八面体配合物(NH₃CH₂CH₂CH₂NH₂)₂[Mo_0.4W_0.6O₂(C₆H₄O₂)₂],并对其进行了单晶结构解析,研究了其与ATP作用的液相NMR谱.该晶体属正交晶系,空间群为Pcan.晶胞参数a=0.7501(2)nm,b=2.3994(7)nm,c=1.2178(4)nm,Z=4.[Mo_0.4W_0.6O₂(C₆H₄O₂)₂]^2-的配位几何构型为手性八面体,晶体为外消旋体.配位阴离子中MoW中心金属离子除了与两个端基O配位形成cis-MO键外,同时还分别与两个邻苯二酚配位基团的的氧原子配位,形成4个M-Ob(M=Mo,W)键,构成两个五元环.利用¹HNMR,¹³CNMR,³¹PNMR以及¹H-¹⁵NHMBC对标题配合物及其与ATP在D₂O溶剂中的作用进行了研究,发现标题配合物的MoW中心金属离子在纯D₂O溶剂中被还原成+5价,但与ATP混合后转化为+6价,且与原配位基邻苯二酚发生解离.解离后的[MO₂]²⁺最大可能与腺嘌呤上的氨基N原子配位,而此配位可能是其抗癌抗肿瘤活性的主要作用机理之一.     

High-temperature High-pressure Hydrothermal Synthesis of Dy3＋-doped YNbO4 Single Crystal and Its Luminescence Properties

Single crystal Dy3＋ doped YNbO4phosphors were prepared via a high-temperature high-pressure hydrothermal procedure. Under excitation at 270 nm, the Dy3＋-doped YNbO4 phosphor shows bright white emission, which is composed of two strong bands at 492 and 576 nm corresponding to the characteristic 4F9/2→6H15/2 and aF9/2→6H13/2 transitions of Dy3＋, respectively. The dominant band was observed at 352 nm, which corresponds to the 6H15/2→6p7/2 transition of Dy3＋. Nearly white light was achieved at 2ex 270, 310 and 388 nm and the CIE（International Commission on Illumination） values were （0.3135, 0.3421）, （0.3088, 0.3380） and （0.3146, 0.3296）, respectively.     

4-甲基苯并-15-冠-5对某些镧系放射性核素的萃取

本文研究了4-甲基苯并-15-冠-5三氯甲烷溶液从苦味酸水溶液中对某些镧系放射性核素(¹⁴⁴Ce、¹⁴⁷Nd、^152+154Eu、¹⁷⁰Tm和¹⁶⁹Yb)的萃取。从斜率分析得出,被萃取状态为1:2:3(金属离子/冠醚/苦味酸根)络合物。在25℃,测定了三价镧系元素的苹取常数(K_ex),得到下列次序:Nd³⁺>Eu³⁺>Ce³⁺>Tm³⁺>Yb³⁺。结果表明,Nd³⁺的离子大小(r=0.995)比其它镧系元素可能更接近4-甲基苯并-15-冠-5环孔的大小。 为了将镧系元素与锕系元素作比较,还测定了4-甲基苯并-15-冠-5对Th⁴⁺、UO₂²⁺和Am³⁺的萃取率,所得到的萃取率次序为Th⁴⁺>Am³⁺UO₂²⁺。实验证明,4-甲基苯并-15-冠-5将可能是溶剂萃取法分离铀和钍的有用试剂。 溶剂和添加剂影响萃取实验表明,在有机相添加正丁醇或异戊醇,或者以高极性的溶剂(例如,硝基苯)替代三氯甲烷,都能显著地增加对镧系元素的萃取。     

The tungsten-tungsten triple bond---18. Bridging and terminal allyl ligands in complexes of the formula W2(R)2(NMe2)4, where R = C3H5 and C4H7

The reaction between RMgCl (two equivalents) and 1,2-W₂Cl₂(NMe₂)₄ in hydrocarbon solvents affords the compounds W₂R₂(NMe₂)₄, where R = allyl and 1− and 2-methyl-allyl. In the solid state the molecular structure of W₂(C₃H₅)₂(NMe₂)₄ has C₂ symmetry with bridging allyl ligands and terminal W---NMe₂ ligands. The W---W distance 2.480(1) Å and the C---C distances, 1.47(1) Å, imply an extensive mixing of the allyl π-MOs with the WW π-MOs, and this is supported by an MO calculation on the molecule W₂(C₃H₅)₂(NH₂)₄ employing the method of Fenske and Hall. The most notable interaction is the ability of the (WW)⁶⁺ centre to donate to the allyl π^*-MO (π₃). This interaction is largely responsible for the long W---W distance, as well as the long C---C distances, in the allyl ligand. The structure of the 2-methyl-allyl derivative W₂(C₄H₇)₂(NMe₂)₄ in the solid state reveals a gauche-W₂C₂N₄ core with W---W = 2.286(1) Å and W---C = 2.18(1) Å, typical of WW and W---C triple and single bonds, respectively. In solution (toluene-d₈) ¹H and ¹³C NMR spectra over a temperature range −80°C to +60°C indicate that both anti- and gauche- W₂C₂N₄ rotamers are present for the 2-methyl-allyl derivative. In addition, there is a facile fluxional process that equilibrates both ends of the 2-methyl-allyl ligand on the NMR time-scale. This process leads to a coalescence at 100°C and is believed to take place via an η³-bound intermediate. The 1-methyl-allyl derivative also binds in an η¹ fashion in solution and temperature-dependent rotations about the W---N, W---C and C=C bonds are frozen out at low temperatures. The spectra of the allyl compound W₂(C₃H₅)₂(NMe₂)₄ revealed the presence of two isomers in solution—one of which can be readily reconciled with the presence of the bridging isomer found in the solid state while the other is proposed to be W₂(η³-C₃H₅)₂(NMe₂)₄. The compound W₂R₂(NMe₂)₄ where R = 2,4-dimethyl- pentadiene was similarly prepared and displayed dynamic NMR behaviour explainable in terms of facile η¹ = η³ interconversions.     

高氯酸锂与4-叔丁基苯并-15-冠-5配合物的远红外位移

冠醚化合物对金属离子具有特定的络合作用 [1,2 ] .在冠醚萃取分离锂同位素过程中 ,4-叔丁基苯并 -1 5 -冠 -5 (4 -t-BB1 5 C5 )是锂同位素效应较大且最接近实用的多醚之一 .它容易合成[3] ,而且已有若干萃取研究[4～ 6 ] .本文合成了高氯酸锂与 4-叔丁基苯并 -1 5 -冠 -5配合物 ,测定了若干表征值和远红外位移 ,并根据已有的理论框架[7] 算得配合物的相对约化配分函数比 [(s/s′) f ]org和碘苯 -水溶液两相平衡过程中锂同位素分离系数 α.为在冠醚体系的锂同位素分离研究中应用红外光谱取代质谱 ,直接测定和计算(1 +εp)值提供了可能性 .…     

Electronic absorption spectrum of Ba(MnO4)2·3H2O/Ba(ClO4)2·3H2O

Polarized absorption spectra of Ba(MnO₄)₂·3H₂O/Ba(ClO₄)₂·3H₂O mixed single crystals are reported at 4.2°K. Previous ¹T₂ → ¹A₁ assignments for the 5200 Å and 3000 Å absorption bands of MnO₄⁻ are substantiated; further support is provided for the ¹T₁ → ¹A₁ assignment of the 3600 Å absorption band of MnO₄⁻. The site-splitting of the 5200 Å ¹T₂ state is E(¹E)−E(¹A) ≈ −150 cm⁻¹; that of the 3000 Å ¹T₂ state is E(¹E)−E(¹A) ≈ 300 cm⁻¹. A significant e vibronic intensity component is observed in the 5200 Å ¹T₂ state.     

The 1B1, 1B2, 1A1, 1A2, 3A′(2B2), and 2A1 states of the 1,1-difluoromethane ion studied using multiconfiguration second-order perturbation theory

The 1²B₁(X²B₁), 1²B₂, 1²A₁, 1²A₂, 2²B₂, and 2²A₁ states of the ion were studied using CASPT2 and CASSCF methods. Calculations suggest that one should consider the 3²A′ state instead of 2²B₂. The CASPT2 T₀ calculations predict the energy ordering of 1²B₁(X²B₁), 1²B₂, 1²A₁, 1²A₂, 3²A′, and 2²A₁, which is in line with the experimental results by Pradeep and Shirley. The CASPT2 T₀ values for the 1²B₂, 1²A₂, 3²A′, and 2²A₁ states are close to the experimental values. The F-loss and H-loss dissociation processes were studied at the CASPT2//CASSCF level. The energy levels of low-lying states of are compared.     

取代基效应对N-4-取代苯亚甲基苯胺与N-4-取代苯亚甲基环己胺NMR和UV光谱影响的差异性

合成了N-4-取代苯亚甲基苯胺(1)与N-4-取代苯亚甲基环己胺(2)两个系列化合物, 测定其¹³C和¹H 核磁共振(NMR)化学位移以及紫外(UV)吸收光谱. 定量对比了取代基效应对两个系列化合物CH=N键的¹³CNMR化学位移δ_C(C=N)和¹H NMR化学位移δ_H以及UV吸收光谱最大波长能量(v_max)的影响差异. 研究结果表明,对于分子骨架相似的化合物(1)和(2), 取代基效应的作用方式存在多样性: (i)化合物(1)的δ_C(C=N)、δ_H以及v_max受到基团的特殊交叉相互作用(Δσ²)的影响显著, 而Δσ²对化合物(2)相应性能的影响很小; (ii)无论化合物(1)还是化合物(2), 取代基场/诱导效应σ_F和共轭效应σ_R对δ_C(C=N)的影响为负相关, 而对δ_H的影响为正相关, 它们对δ_C(C=N)和δ_H的影响正好相反. 另一方面, 场/诱导效应σ_F对(1)和(2)的δ_C(C=N)影响重要, 而对它们的δ_H影响很小; (iii)化合物(1)和(2)的δ_C(C=N)、δ_H以及v_max的变化规律, 可分别建立通用方程表达, 其中与CH=N的N原子键连苯基的影响可由指示变量(I)表示, 该苯基对三种性能分别有固定的贡献.     

Stabile Bis(η-alkin)MCl2-komplexe; Darstellung und reaktivität

The synthesis and reactivity of {(η⁵-C₅H₄SiMe₃)₂Ti(CCSiMe₃)₂} MCl₂ (M = Fe: 3a; M = Co: 3b; M = Ni: 3c) is described. The complexes 3 are accessible by the reaction of (η⁵-C₅H₄SiMe₃) ₂Ti(CSiMe₃)₂ (1) with equimolar amounts of MCl₂ (2) (M = Fe, Co, Ni). 3a reacts with the organic chelat ligands 2,2′-dipyridyl (dipy) (4a) or 1,10-phenanthroline (phen) (4b) in THF at 25°C to afford in quantitative yields (η⁵-C₅H₄SiMe₃)₂Ti(CSiMe₃)₂ (1) and [Fe(dipy)₂]Cl₂ (5a) or [Fe(phen)₂]Cl₂ (5b). 1/n[Cu^IHal]_n (6) or 1/n[Ag^IHal]_n (7) (Hal = Cl, Br) react with {(η⁵ -C₅H₄SiMe₃)₂Ti(CCSiMe₃)₂}FeCl₂ (3a), by replacement of the FeCl₂ building block in 3a, to yield the compounds {(η⁵-C₅H₄SiMe₃)₂Ti(C CSiMe₃)₂}Cu^IHal (8) or {(η⁵-C₅H₄SiMe₃)₂Ti(CSiMe₃)₂}Ag^IHal (9) (Hal = Cl, Br), respectively. In 8 and 9 each of the two Me₃SiCC-units is η²-coordinated to monomeric Cu^I Hal or Ag^IHal moieties. Compounds 8 and 9 can also be synthesized by the reaction of (η⁵-C₅H₄SiMe₃)₂ Ti(CSiMe₃)₂ (1) with 1/n[Cu^IHal]_n (6) or 1/n [Ag^IHal]_n (7) in excellent yields. All new compounds have been characterized by analytical and spectroscopic data (IR, ¹H-NMR, MS). The magnetic moments of compounds 3 were measured.     

Azo-containing phosphine complexes of palladium(II) and platinum(II) and their effectiveness in the Heck reaction: crystal and molecular structure of [PdCl2{PPh2{1-(4-MeC6H4N2)-2-OC(O)Me---C10H5}]·2EtOH

Reaction of Na[MCl₄] (M=Pd or Pd) with the azo-containing phosphines Ph₂P{1-(4-RC₆H₄N₂)-2-OR′-C₁₀H₅} {R=Me (I), NMe₂ (II); R′=C(O)Me} affords the complexes [MCl₂L₂] (1–4) in good yield. Complexes 1–4 have all been fully characterised by elemental analysis, ¹H-, ¹³C{¹H}-, and ³¹P{¹H}-NMR spectroscopy and UV–visible spectroscopy. The use of 1 in the Heck reaction has been investigated and shown to effect up to 1000 turnovers.     

Characterization and decomposition mechanism of an unusual nickel, thiocyanate and 4-methylpyridine polymeric complex

The synthesis, characterization, and thermal decomposition of the [Ni(SCN)₂(H⁺SCN)₂(4-mepy)₂] compound with an octahedral structure in polymeric chain were reported, in which SCN groups form bridges among Ni(II) ions. The compound decomposes in water resulting in a pH<4 solution. The FT-IR spectrum presented doublet bands at 2117; 2128 cm⁻¹, 788; 773 cm⁻¹ assigned to ν(C---N) and ν(C---S) stretching modes, respectively, and δ(SCN) deformation modes at 468; 476 cm⁻¹. The Raman spectrum of the compound presented the ν(C---N) stretching as a strong doublet at 2122; 2128 cm⁻¹, ν(C---S) at 783; 770 cm⁻¹, and δ(SCN) at 468; 477 cm⁻¹. No significant changes were observed in the 4-mepy ligand bands compared with the vibrational frequencies of the pure compound or the compound in aqueous solution 0.2 mol l⁻¹. The crystal UV–vis reflectance spectrum presented two bands centered in 626 and 424 nm tentatively assigned to the d→d type transitions, ³A_2g→³T_1g and ³A_2g→³T_1g, for a symmetry close to O_h. The TG curve showed a mass loss between 120 and 200 °C assigned to the loss of the two 4-mepy molecules; from 200 to 265 °C, the loss of the two H⁺SCN groups; and from 265 to 450 °C, the loss of the two SCN groups that formed the bridges among the nickel atoms. Based on these mass loss data, a mechanism of thermal decomposition for the compound was proposed.     

Structure and conformation of 2,3,4-triphenyl-1-oxa-4-azabutadiene

2,3,4-triphenyl-1-oxa-4-azabutadine (C20H15NO) has been studied by X-ray analysis and AM1 molecular orbital methods. It crystallises in the triclinic space group P-1 with a=9.414(3), b=10.479(3), c=8.385(2) Å, =103.31(3)°, β=97.10(3)°, γ=74.09(1)°, V=772.5(4) ų, Z=2, D_c=1.227 gcm⁻³, and μ(MoK)=0.075 mm⁻¹ and F₀₀₀=300. The structure was solved by direct methods and refined to R=0.043 for 2672 reflections [I>2σ(I)]. The conformational analysis of the title compound were investigated by semi-empirical quantum mechanical AM1 calculations. The minimum conformation energies were calculated as a function of the three torsion angles θ₁(O(1)C(7)C(8)N(1)), θ₂(C(8)N(1)C(15)C(16)) and θ₃(C(14)C(9)C(8)N(1)). The results are compared with the X-ray results. C=O and C=N groups are twisted about each other by 95.5(2)°.     

High temperature reaction of SiCl4 and O2 in quartz tubes

The reaction between SiCl₄ and O₂ at 1 atm between 25 and 1200°C has been followed by mass spectrometry. Below 600°C no reaction with O₂ is noted. Above 600°C the reaction proceeds in two steps. Between 800 and 1000°C the ²⁸Si/³²O₂ peak height ratio is constant with no evolution of Cl₂. It is suggested that silicon oxychlorides are being formed in this temperature regime. Above 1000°C the reaction between SiCl₄ and O₂ intensifies with concomitant production of Cl₂. It is suggested that above 1000°C the reaction SiCl₄ + O₂ → SiO₂ + Cl₂ becomes important.

At low temperatures (<800°C) adsorbed H₂O and OH groups from the surface of the fused silica tube react with SiCl₄ to form HCl. The importance of this reaction decreases with increasing temperature. The increased production of HCl above 1000°C is ascribed to H₂O and H₂ diffusing from the tube.     

4-硝基咪唑A-带激发态结构动力学

通过共振拉曼光谱实验和量子化学计算的方法研究了4-硝基咪唑(4NI)A-带激发态衰变动力学.对4NI的振动光谱、紫外电子吸收光谱、荧光光谱和共振拉曼光谱进行了指认.在全活化空间自洽场法(CASSCF)/6-31G(d)计算水平下获得了单重激发态S1(nOπ*)和S2(ππ*)和势能面交叉点S1(nOπ*)/S2(ππ*)的优化几何结构和能量,分析了A-带共振拉曼光谱的强度模式特征,获得了短时结构动力学,并结合全活化空间自洽场法(CASSCF)理论计算结果确定了4NI在S2(ππ*)态衰变通道主要是S2,FC→S2,min(ππ*)→S0辐射弛豫.     

Synthesis and Characterization of Zinc Succinate, Zn(C4H4O4)

Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｓｕｃｃｉｎａｔｅｉｏｎ (Ｃ4Ｈ4Ｏ4) 2 -(—ＯＯＣＣＨ2 ＣＨ2 ＣＯＯ— )ｉｓａｖｅｒｓａｔｉｌｅｌｉｇａｎｄｓｉｎｃｅｅａｃｈｏｆｔｈｅｆｏｕｒｔｅｒｍｉｎａｌｃａｒｂｏｘｙｌｏｘｙｇｅｎｓｉｓａｂｌｅｔｏｐａｒｔｉｃｉｐａｔｅｉｎｃｏｏｒｄｉｎａｔｉｏｎｔｏｃｅｎｔｒａｌｍｅｔａｌａｔｏｍ(ｓ)ｉｎａｄｄｉｔｉｏｎｔｏｔｈｅｆｌｅｘｉｂｉｌｉｔｙｏｆｔｈｅＣ—Ｃｂｏｎｅ .Ｓｕｃｈｃｏｏｒｄｉｎａｔｉｎｇｖｅｒｓａｔｉｌｉｔｙｈａｓｂｅｅｎｒｅｆｌｅｃｔｅｄｉｎｓｅｖｅ…     

Hydrothermal synthesis, crystal structure and characterization of [Zn(H2O)4]2 [H2As6V15O42(H2O)]·2H2O

The compound [Zn(H₂O)₄]₂[H₂As₆V₁₅O₄₂(H₂O)]·2H₂O (1) has been synthesized and characterized by elemental analysis, IR, ESR, magnetic measurement, third-order nonlinear property study and single crystal X-ray diffraction analysis. The compound 1 crystallizes in trigonal space group R3, a=b=12.0601(17) Å, c=33.970(7) Å, γ=120°, V=4278.8(12) Å³, Z=3 and R1(wR2)=0.0512 (0.1171). The crystal structure is constructed from [H₂As₆V₁₅O₄₂(H₂O)]⁴⁻ anions and [Zn(H₂O)₄]²⁺ cations linked through hydrogen bonds into a network. The [H₂As₆V₁₅O₄₂(H₂O)]⁶⁻ cluster consists of 15 VO₅ square pyramids linked by three As₂O₅ handle-like units.     

卤代芳香族羧酸与含氮配体合成镧系配合物的结构、热化学和荧光性质（英文）

采用室温溶液挥发法合成了五种结构新颖的镧系配合物,其结构通式为[Ln(2,4-DFBA)₃(phen)]₂ (Ln=Sm 1, Eu2, Er 3, 2,4-DFBA为2,4二氟苯甲酸的简写,phen为1,10-菲啰啉的简写),[Ln(2-Cl-6-FBA)₂(terpy)(NO₃)(H₂O)]₂ (Ln=Tb4, Dy 5, 2-Cl-6-FBA为2-氯-6-氟苯甲酸的简写, terpy为2,2’:6’2’’-三联吡啶的简写)。五个配合物可以分为两个系列,使用不同的镧系离子作为中心离子。通过X射线单晶分析,5种配合物均属于单斜晶系,空间群为P21/n。配合物1,2和配合物3虽然具有相同的分子通式,但配位方式明显不同,形成了前者为9配位的松饼型,后者是8配位的双帽三棱柱几何构型。二维面状超分子结构的形成方式也明显不同,区别在于配合物1和2通过微弱的π-π堆积作用形成。配合物4和5是同构的,结构中引入了硝酸根离子较为有趣,通过C―H···F氢键和π-π堆积作...     

Theoretical study on reaction mechanism of the vinyl radical with nitrogen atom

The complex triplet potential energy surface of the C₂H₃N system is investigated at the UB3LYP and CCSD(T) (single-point) levels in order to explore the possible reaction mechanism of C₂H₃ radical with N(⁴S). Eleven minimum isomers and 18 transition states are located. Possible energetically allowed reaction pathways leading to various low-lying dissociation products are obtained. Starting from the energy-rich reactant C₂H₃+N(⁴S), the first step is the attack of the N atom on the C atom having one H atom attached in C₂H₃ radical and form the intermediate C₂H₃N(1). The associated intermediate 1 can lead to product P₁ CH₂CN+H and P₂ ³CH₂+³HCN by the cleavage of C–H bond and C–C bond, respectively. The most favorable pathway for the C₂H₃+N(⁴S) reaction is the channel leading to P₁, which is preferred to that of P₂ due to the comparative lower energy barrier. The formation of P₃ ³C₂H₂+³NH through hydrogen-abstraction mechanism is also feasible, especially at high temperature. The other pathways are less competitive comparatively.     

Intramolecular hydrogen bonds and hydrogen-bonded systems in di-Schiff bases of 4-methyl-isophthalaldehyde with 4-substituted anilines

Three di-Schiff bases of 2-hydroxy-5-methyl-isophthalaldehyde with 4-R-anilines (R=H, CH₃, OCH₃) and their 1:1 complexes with HClO₄ were studied by FT-IR, ¹H, and ¹³C NMR spectroscopy in acetonitrile and [²H₃]acetonitrile solutions, respectively. In di-Schiff bases intramolecular OH…N hydrogen bonds have been detected; however, they show no proton polarizability. Hydrogen-bonded systems with fast proton fluctuation and large proton polarizability have been found in the 1:1 complexes of di-Schiff bases with HClO₄.