Synthesen von Heterocyclen, 57. Mitt.: Über Reaktionen mit Kohlensuboxyd

Zusammenfassung Weitere 4-Hydroxy-[1,3-thiazinone-(6)]¹ werden aus Thioamiden und Kohlensuboxyd synthetisiert und u. a. das Verhalten des C₃O₂ gegenüber Acetondicarbonsäureanhydrid bzw. Harnstoff untersucht.     

Structural investigation of the EuBa2Cu3O7-δ high TC superconductor by 151Eu, 119Sn, 57Fe and 57Co Mössbauer spectroscopy

By introducing ¹⁵¹Eu, ¹¹⁹Sn, ⁵⁷Fe and ⁵⁷Co into the orthorhombic perovskite lattice of YBa₂Cu₃O_7-δ high T_C superconductors, the localization and distribution of these probe nuclides were investigated by Mössbauer spectroscopy in order to get further information on the structure of high T_C superconductors. The Mössbauer spectra of superconductor samples were considered as superpositions of subspectra belonging to Mössbauer nuclides occupying different sites with various surroundings in the lattice. The ¹⁵¹Eu spectra were evaluated as singlets corresponding to Eu^III situated at the normal rare earth site. The ¹¹⁹Sn spectra were decomposed into a singlet and a doublet, which were associated with Sn^IV at the Cu(2) and the Cu(1) sites, respectively. The ⁵⁷Fe and ⁵⁷Co spectra could be fitted with three doublets representing Fe^III and Fe^IV at the Cu(1) site as well as Fe^III at the Cu(2) site. Comparing the relative area fractions of Mössbauer lines corresponding to different Cu sites it was suggested that iron and cobalt prefer the Cu(1) site, while tin prefers the Cu(2) site in these superconductors.     

杂富勒烯的电子结构与性质关系的研究：Ⅱ.C57X3,C56X4（X=B,N,P）的位 …

用ＣＮＤＯ／２方法在５８６微机上计算了Ｃ５７Ｘ３，Ｃ５６Ｘ４的２３４个位置异构体的电子结构。在Ｃ５７Ｘ３位置异构体中，Ｃ５７Ｘ３分别是最稳定的。对于Ｃ５６Ｘ４位置异构体，Ｃ５６Ｂ４，Ｃ５６Ｎ４和Ｃ５６Ｐ４分别是最稳定的，但稳定性都比Ｃ６０差。其氧化或还原性都比Ｃ６０好，将它们和Ｃ６０比较，与Ｘ相距一个或两个健的Ｃ原子电荷密度增加或减少较多，其亲电或亲核反应性增加；     

GC-MS/FID测定环境空气中57种臭氧前体物

建立了GC-MS/FID测定环境空气中57种臭氧前体物的分析方法.优化三级冷阱捕集温度、三级冷阱解析温度、初始柱温、毛细管色谱柱等实验条件.优化条件为:采用硅烷化的苏玛罐采集环境空气,目标组分经三级冷阱在-180℃低温浓缩富集,80℃解析,初始柱温为15℃,结合中心切割技术,将乙烷、乙烯、乙炔、丙烷、丙烯切割至TG-B...     

57Fe- and119Sn-Mössbauer effect of oxide glasses

Coordination number of network-former (NWF) and formation of nonbridging oxygen (NBO) at the site neighboring to NWF can be estimated from Mössbauer measurements, since small amounts of Fe³⁺ and Sn⁴⁺ substitute NWF in several oxide glasses. Gamma-ray or thermal neutron irradiation of oxide glasses causes electron or charge transfer from oxygen to the Mössbauer ions, and the probability depends on the fraction of NBO. On the contrary, -ray irradiation of phosphate glasses results in oxidation of Fe²⁺ to Fe³⁺ since iron plays a role of network modifier (NWM) at interstitial sites. Debye temperature _D obtained from low-temperature Mössbauer measurements reflects the site occupation of Mössbauer ions in glasses. A linear relationship between glass transition temperature (T _g ) and quadrupole splitting () of Fe³⁺,T _g — rule, is also effective for determining the site occupation of Mössbauer ions.     

Mössbauer investigation of 57Fe-doped TlSr2CoO5

The thallium cobaltite TlSr₂CoO₅ undergoes a metal—insulator transition near room temperature. Mössbauer investigation of a ⁵⁷Fe-doped sample shows that iron actually enters into the lattice and that a long range antiferromagnetic order sets in below 150 K explaining the origin of a peak previously observed in the temperature dependence of the magnetic susceptibility. An unexpected complex behaviour is found for the high temperature phase for which previous electron diffraction and X-ray diffraction studies revealed a single site for Co atoms. The results are interpreted in terms of a dynamical formation of two types of structural domains characterized by a fluctuation of Co-O bond lengths inducing a fluctuation of Co spin state.     

57Fe Mössbauer, XRD and DTA Study of the Crystallization Behavior of Calcium Aluminate Glass Containing Iron(III)

Certifications of trace elements in existing CRMs, especially biological CRMs, are far from satisfactory. Neutron activation analysis (NAA) for its inherent advantages combined with newly established parametric standardization, may contribute to improve this situation. The continuing progress of the hybrid extended k ₀-relative NAA technique developed in our laboratory is discussed. Examples are given to show the reliability of the method in certification of multielements. RNAA is still one of the best methods, or even the method of choice, in analysis at sub-g/g concentration levels. The suitability of the technique for this purpose has been studied through the determination of rare earth elements at ng/g concentration level in two Chinese biological CRMs using both RNAA and ICPMS. Sampling behaviors of multielements in CRMs have been studied by INAA in an effort to develop CRMs suitable for analysis with small sample sizes.     

向光素LOV1-C57S固态Photo-CIDNP效应的磁场依赖性

利用13C魔角旋转NMR波谱对向光素LOV1-C57S进行固态Photo-CIDNP效应的磁场依赖性研究.在4.7 T(相当于200 MHz1H频率)磁场中,黑暗条件下只检测到较宽的蛋白质信号;但在光照条件下,观测到强烈的固态Photo-CIDNP效应.与在2.3 T(相当于100 MHz1H频率)磁场中得到的全部为发射谱(负)信号的固态Photo-CIDNP图谱(首次在非光合反应系统中观测到的Photo-CIDNP效应)不同,在4.7 T磁场中测得的光诱导13C NMR谱呈现吸收/发射混合峰型,这种峰型与文献报道的LOV2的液态Photo-CIDNP波谱的峰型相似.对比两种磁场中所得谱图发现,向光素LOV1-C57S的固态Photo-CIDNP效应具有强烈的磁场依赖性,而且不同的核对磁场的依赖程度差别很大,这种巨大的差别反映出在被测试的自由基对中的超精细相互作用影响因素发生了很大的改变.     

57Fe-Mössbauer study of electrically conductive alkaline iron vanadate glasses

A relationship between local structure, thermal stability and electrical conductivity (σ) of xR₂O·10Fe₂O₃·(90 ? x)V₂O₅ glasses (abbreviated as xRFV glasses, where R = Li, Na, K; x = 20 and 40 in mol %) was investigated by ⁵⁷Fe-Mössbauer spectroscopy, X-ray diffractometry, differential thermal analysis (DTA) and DC two- and four-probe method. From DTA study, thermal stability of 20RFV glasses is lower than that of 40RFV glasses by evaluating Hruby parameter (K _gl). Constant activation energy for crystallization (E _a) of 2.5 eV obtained from both 20RFV and 40RFV glasses indicate that the crystallization proceeds with the cleavage of Fe–O bond having the energy of 2.6 eV. Isochronally annealed 20RFV glass at 400–450 °C resulted in the increase in electrical conductivity (σ) from the order of 10^?3 to 10^?1 S cm^?1, whereas slight decrease in σ was observed for 20RFV glass annealed above 460 °C. A paramagnetic doublet with an identical isomer shift (δ) of 0.39 mm s^?1 was observed in the ⁵⁷Fe-Mössbauer spectra of 20RFV glass after isothermal annealing conducted at 400–450 °C for 100 min, which caused a decrease of quadruple splitting (Δ) from 0.67 to 0.52 mm s^?1 for 20LiFV glass and from 0.66 to 0.53 mm s^?1 for 20NaFV glass. On the other hand, three paramagnetic doublets with δ and Δ of 0.40 and 0.25, 0.38 and 0.60, and 0.31 and 1.11 mm s^?1 respectively were observed for 20RFV glass annealed at 460–550 °C, reflecting precipitation of semiconducting FeVO₄ phase having σ of 6.0 × 10^?7 S cm^?1. It can be concluded that isochronal annealing of 20RFV glass below 450 °C resulted in increase in σ due to the structural relaxation, while annealing above 500 °C resulted in the decrease of σ due to the precipitation of FeVO₄ phase.     

Vibrational and 57Fe-Mössbauer spectra of FeTbGe2O7

The infrared, Raman and 57Fe-M?ssbauer spectra of FeTbGe2O7 were recorded and analyzed on the basis of its crystallographic data. For comparative purposes, similar measurements were also performed with FeYGe2O7 and with other isostructural compounds containing different lanthanide cations.     

57Co Mössbauer Emission Study of LiNbO3, Fe:LiNbO3 and Mg:LiNbO3 in Various Thermochemical Reduction States

⁵⁷Co Mössbauer emission spectra of undoped and Fe or Mg melt-doped LiNbO₃ single crystals show substantial amounts of the nucleogenic Fe³⁺ charge state (*Fe³⁺) which was generated as an after-effect of the electron-capture of ⁵⁷Co²⁺. The proportion of *Fe³⁺ is markedly dependent on the Mg content and on the stoichiometry of the sample. Electron trapping is described within the model of competing acceptors. The capabilities of the model are investigated in defect structure analysis and charge trapping studies of LiNbO₃.     

57Fe Mössbauer spectroscopy on multiwalled carbon nanotubes with metal filling

M?ssbauer measurements at different temperatures are reported for MWCNTs with metallic encapsulations ("nanowires"). The spectra can reasonably be refined with two subpatterns: one providing clear evidence of an iron carbide Fe(3)C (cementite) phase as the main nanowire component and the other yielding a relaxation doublet most probably belonging to the same phase. Whereas the former one displays a well resolved magnetic hyperfine spectrum with Brillouin type temperature dependence, the latter one gains importance with rising temperature or onset of an inhomogeneous external magnetic field. The comparably large incoherent scattering is attributed to the graphene layers of the tube walls. The experimental results are discussed on the background of an interpretation model trying to explain unusual magnetometric results published elsewhere.     

57Fe Mössbauer spectroscopic and magnetic study of a spin-crossover polymer complex, Fe(3-chloropyridine)2Ni(CN)4

The coordination polymer Fe(3-chloropyridine)₂Ni(CN)₄ (2) has been prepared by a method similar to that for Fe(pyridine)₂Ni(CN)₄ (1). The complex (2) has been characterized by⁵⁷Fe Mössbauer spectroscopy and a SQUID technique.⁵⁷Fe Mössbauer and magnetic susceptibility data show that complex (2) exhibits spin-crossover behavior. The spin transition of (2) occurs between 120 and 80 K with very small hysteresis or without hysteresis. The temperature range of the spin transition in (2) is lower than that in (1). A residual high spin iron(II) fraction is observed at low temperatures in (2), being different from (1). SQUID data also show that samples treated differently yield different spin transition curves.     

OXO CENTERED HETEROTRINUCLEAR TRANSITION METAL CAR- BOXYLATE COMPLEXES 5,~(57)Fe MOSSBAUER SPECTRA AND ELEC-TRON TRANSFER PROPERTIES OF COMPLEXES Fe_2MO(RCOO)_6L_3(M= Mn,Co,Ni)

<正> The 57Fe Mossbauer spectra of mixed-valence heterotrinuclear carboxylate complexes, [Fe2MO(OOCCH3)6Py3]. Py (M = Mn,Co,Ni,Py = Pyridine) and Fe2MO-(OOCCC13 )6THF3 (M = Mn, Co, Ni, THF = Tetrahydrofuran ) indicated that these Fe2M complexes are all valence-trapped on the 57Fe Mossbauer time scale (10-8s) both at 77 K and at room temperature. Expanding the PKS model to asymmetric tricenteral systems showed that intramolecular electron transfer in Fe2M complexes is difficult due to asymmetry of the Fe2MO(RCOO)6L3molecule and high potential-energy barrier.     

SYNTHESIS AND CRYSTAL STRUCTURE OF 5, 10, 15, 20, 22, 24-HEXAHYDRO-5, 5, 10, 10, 15, 15, 20, 20-OCTAMETHYL-PORPHINE

<正> The title com pound (HHOMP) has been synthesized with the pho-toinduced condensation of acetone and pyrrole in the presence of iodoaromatic hydrocarbons, and its molecular and crystal structures have been determined by X-ray analysis. C28H36N4, Mr = 428. 63, triclinic; space group P1; a =10. 165(3), b = 10. 185(2), c=13. 012(3)(?); α=85. 41(2), β=67. 84(2), γ= 89. 75(2)°; V = 1243 (?)3; Z = 2; D = 1. 145g. cm-3; μ= 0. 635cm-1; F (000) = 464. Although the HHOMP molecule twists, it is found that the four nitrogen atoms are still in a plane.     

顶空气相色谱-质谱法同时测定蜂蜜中57种挥发性有机溶剂残留

建立了顶空气相色谱-质谱(HS-GC/MS)同时测定蜂蜜中57种挥发性有机溶剂(包括烷烃类、芳香烃类、醇类、酮类、酯类、醚类)残留量的分析方法。蜂蜜样品在密封的顶空瓶中用水溶解后,在顶空仪中于80 ℃下平衡30 min,使气-液两相达到动态平衡。采用DB-624毛细管色谱柱(60 m×0.25 mm×1.40 μm)对57种有机溶剂进行分离,GC/MS测定,外标法定量。该方法对于烷烃类、芳香烃类和醚类挥发性有机溶剂在0.005～0.2 μg、酯类0.05～2.0 μg、酮类0.5～20 μg、醇类2.5～100 μg范围内线性关系良好,相关系数均大于0.996。对于烷烃类、芳香烃类和醚类挥发性有机溶剂在1.0～20 μg/kg、酯类10～200 μg/kg、酮类100～2000 μg/kg、醇类500～10000 μg/kg添加范围内的平均添加回收率为61.0%～113.1%,相对标准偏差为1.9%～9.8%。对于烷烃类、芳香烃类和醚类挥发性有机溶剂的检出限为1.0 μg/kg、酯类10 μg/kg、酮类100 μg/kg、醇类500 μg/kg。该方法操作简单、快速,灵敏度和准确度高,适用于蜂蜜样品中多种挥发性有机溶剂残留量的同时检测。     

ZSM-5、ZSM-57分子筛和丝光沸石间的转晶规律

考察了硅铝比、碱度、有机胺模板剂、晶化时间及温度等合成条件对ZSM-5、ZSM-57 分子筛和丝光沸石之间相互转晶的影响. 发现较高的碱度、较长的晶化时间有利于合成丝光沸石；较低的碱度、较高的诱导晶化温度、较长的晶化时间有利于合成低硅铝比的ZSM-57 分子筛；合成低硅铝比的ZSM-5分子筛则需要在能合成丝光沸石和ZSM-57 分子筛的碱度区间内精确调节碱度, 缩短晶化时间、降低诱导晶化温度、加入适当晶种, 有利于合成低硅铝比的ZSM-5 分子筛. 合成条件稍微改变, 会导致各种沸石之间发生转晶, 晶化产物出现两种或两种以上的晶型.     

在小硅化物SiX^m4（X=H,He,Li,Be,O,F,Ne,Na,Mg,S,Cl,Ar;m=0,…

用从头算方法，在ＨＦ／ＳＴＯ－３Ｇ、ＨＦ／３－２１Ｇ和ＨＦ／６－３１Ｇ水平上研究了小硅化物ＳｉＸ＾ｍ４的成键倾向性。计算结果表明，所研究的分子势能曲线均有稳定的极小值（ＳｉＬｉ４除外）。与已知的稳定分子ＳｉＨ１、ＳｉＦ４和ＳｉＣｌ４比较，含惰性元素的未知分子ＳｉＨｅ＾４＋４、ＳｉＮｅ＾４＋４和ＳｉＡｒ＾４＋４比含碱金属和碱土金属的未知分子ＳｉＬＩ４、ＳｉＮａ４、ＳｉＢｅ＾４＋４和ＳｉＭｇ＾４＋４有