NIEDERKOORDINIERTE PHOSPHORVERBINDUNGEN, 701 1-METALLA-2,5-DIPHOSPHA PENTA-1,3-DIENE DURCH 1,4-ADDITION VON METALLCARBONYLCYCLOPENTADIENYLHYDRIDEN AN 1,4-DIPHOSPHABUTA-1,3-DIEN

Abstract

Reactions of carbonyl cyclopentadienyl hydrides from molybdenum and tungsten with 1,4-diphosphabuta-1,3-diene yield metalla-diphospha-pentadiene with a metal-phosphorus-double bond.

Metalla-diphosphapentadiene mit einer Metall-Phosphor-Doppelbindung werden durch Umsetzung von Carbonylcyclopentadienylhydriden des Molybdäns und Wolframs mit einem 1,4-Diphospha-buta-1,3-dien erhalten.     

The Determination of the Titre of Ascorbic Acid Standard Solutions

Abstract

A new method for the determination of the titre of ascorbic acid standard solutions employing potassium dichromate as a primary standard has been developed. In a pyrophosphate medium, the pyrophosphate complex of divalent manganese is oxidized by dichromate to the pyrophosphate complex of tervalent manganese; the latter oxidizes o-tolidine reversibly with formation of the corresponding quinonediimine, which is visually titrated by the ascorbic acid standard solution.     

Synthesis and Structure of Bis(2-Amino-5-Cyanopyridinium) Diaquadichlorocopper(II) Dichloride

The reaction of CuCl₂ with 2-amino-5-cyanopyridine and HCl in 1-propanol gave bis(2-amino-5-cyanopyridinium) diaquadichlorocopper(II) dichloride (1). Crystal data for 1 are: monoclinic, space group: P2₁/c, a = 8.461(3) Å, b=14.665(5) Å, c=7.883(3) Å, g =96.105(4)°, V=972.6(6) Å 3 , Z=2, D_calc =1.645 Mg/m³, w =1.691 mm^?1, F(OOO)=486, MoK _f( u =0.71073 Å), R1=0.0431 for [∣I∣ S 2 σ (I)] and R1=0.0680 for all 1944 unique reflections and 130 parameters. The structure exists as square planar Cu(H₂O)₂Cl₂ units with long semi-coordinate bonds to the cyano nitrogens of the 2-amino-5-cyanopyridinium ions. Hydrogen bonding from the water molecules and N―H hydrogens to the chloride irons stablises the lattice.     

Synthesis and Spectroscopic Characterization of Silver(I) Complexes of Selenones

Silver(I) complexes of selenones, [LAgNO₃] and [AgL₂]NO₃ (where L is imidazolidine-2-selenone or diazinane-2-selenone and their derivatives) have been prepared and characterized by elemental analysis, IR and NMR (¹H, ¹³C and ¹⁰⁷Ag) spectroscopy. An upfield shift in the C=Se resonance of selenones in ¹³C NMR and a downfield shift in N-H resonance in ¹H NMR are consistent with selenium coordination to silver(I). In ¹⁰⁷Ag NMR, the AgNO₃signal is deshielded by 450-650 ppm on coordination to selenones. Greater upfield shifts in ¹³C NMR were observed for [LAgNO₃] compared to [AgL₂]NO₃complexes, whereas the opposite trend was observed for ¹H and¹⁰⁷Ag NMR chemical shifts.     

Interaction of Cationic Manganese Porphyrins with DNA. A Binding Model

The DNA cleavage properties of two cationic manganese porphyrins possessing different peripheral substituents were compared. The identical nature of the strand scission patterns of the porphyrins on a 139 base pair restriction fragment of pBR-322 DNA, along with other evidence, suggests that the porphyrin is end-on bound via the minor groove in a melted or partially melted region of DNA. This unusual binding mode underscores the potential of outisde binding cationic metalloporphyrins as probes for low melting regions of DNA     

Si含量对高锰硅化合物相组成及热电性能的影响研究

采用高频感应熔融、退火结合放电等离子烧结方法制备高锰硅(HMS)化合物MnSi1.70+x(x=0,0.05,0.1,0.15),系统研究了Si含量变化对材料相组成、微结构和热电性能的影响规律.结果表明,当x0.1时,样品由HMS和贫Si的MnSi金属相两相组成,随着Si含量x的增加,MnSi相相对含量减小;当x=0.1时,所得样品为单相HMS化合物;当x0.1时,样品由HMS和过量Si两相组成.随着x的增加,由于样品中高电导的金属相MnSi含量逐渐减少,样品的电导率逐渐下降,而Seebeck系数随之增加.室温下样品载流子浓度和有效质量随x增大逐渐减小,而迁移率逐渐增加.MnSi和Si杂相与HMS相比均为高热导相,因此当x=0.1时,由于样品为单相HMS,从而表现出最低热导率和最高ZT值.MnSi1.80样品在800K时热导率最小值达到2.25W·m-1K-1,并在850K处获得最大ZT值(0.45).     

Effect of manganese addition on physical properties of Co0.6Zn0.4MnxFe2-xO4 system

X-ray analysis and magnetic properties have been studied for the system Co_0.6Zn_0.4Mn_xFe_2-xO₄. The bulk density, X-ray density and porosity were also studied. It was found that the lattice constant decreased with increasing manganese concentration x. The X-ray density, the bulk density and porosity do depend on the manganese content. The magnetic susceptibility and the activation energies were found to be increased with increasing percentage of the manganese ions while the dc conductivity decreased.     

Изотопные мишени для ядерных исследований

A non-contact measuring method on electrostatic potential by using α-ray ionization is proposed. In this method potential of a charged material is estimated from ionic current flowing through an ion collector attached with a small ²⁴¹Am source. As hade electrode surrounding the collector has a function of adjusting sensitivity and potential up to 50 kV was measured with precision of 1 kV.     

Labelling and Fractionating of Black Mamba Venom using 131I and Gel-Filtration Technique

Separation of Black Mamba (Dendroaspis polylepis) venom into three fractions was achieved by the use of Sephadex G-100 filtration method. The first and highest peak of the three separated bands proved to be the lethally toxic. Labelling the venom with nascent¹³¹ I prior to fractionating facilitated the detection and the evaluation of three well resoluted fractions. Comparative separation of non-labelled venom was also carried out side by side with the labelled one to study the advantage of radioactivity on extinction measurements.     

Separation of Carrier Free Manganese-54 and Iron-59 Using Reversed Phase Partition Chromatography

Carrier free radioactive ⁵⁴Mn and ⁵⁹Fe enjoy favoured position in industrial, agricultural and medical applications [1]. The main methods used for their isolation from suitable irradiated targets are mainly based on solvent extraction [2] or ion exchange [3].