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Reactions of Iron Trichloride with Trithyazyl Chloride. Crystal Structure of [S4N4Cl]+[FeCl4]? Iron trichloride reacts with (NSCl)3 yielding S4N4[FeCl4]2, S3N3Cl2[FeCl4] or S4N4Cl[FeCl4], depending on the reaction conditions. The i.r. spectra prove the presence of [FeCl4]? ions for all three compounds. The 57Fe-Mössbauer spectra show a slight quadrupole splitting at 80 K for S3N3Cl2[FeCl4] (ΔEQ = 0.42 mm · s?1) and S4N4Cl[FeCl4] (ΔEQ = 0.23 mm · s?1), which indicates a slight deformation of the FeCl4? tetrahedra. The crystal structure of S4N4Cl[FeCl4] was determined and refined with X-ray diffraction data (2549 independent reflexions, R = 0.026). S4N4Cl[FeCl4] crystallizes in the triclinic space group P1 with two formula units per unit cell. The lattice constants are a = 712, b = 911, c = 1006 pm, α = 76.5°, β = 83.8° and γ = 80.5°. The structure consists of the so far unknown [S4N4Cl]⊕ cations and slightly deformed FeCl4? ions. The [S4N4Cl]⊕ ion consists of a S4N4 ring built up of two nearly planar S3N2 fragments having a dihedral angle of 136°. The average SN bond length is 157 pm, the SCI bond length 214 pm. 相似文献
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Reactions of Uranium Pentabromide. Crystal Structures of PPh4[UBr6], PPh4[UBr6] · 2CCl4, (PPh4)2[UBr6] · 4CH3CN, and (PPh4)2[UO2Br4] · 2CH2Cl2 PPh4[UBr6] and PPh4[UBr6] · 2CCl4 were obtained from UBr5 · CH3CN and tetraphenylphosphonium bromide in dichloromethane, the latter being precipitated by CCl4. Their crystal structures were determined by X-ray diffraction. PPh4[UBr6]: 2101 observed reflexions, R = 0.090, space group C2/c, Z = 4, a = 2315.5, b = 695.0, c = 1805.2 pm, β = 96.38°. PPh4[UBr6] · 2CCl4: 2973 reflexions, R = 0.074, space group P21/c, Z = 4, a = 1111.5, b = 2114.2, c = 1718.7 pm, β = 95.42°. Hydrogen sulfide reduces uranium pentabromide to uranium tetrabromide. Upon evaporation, bromide is evolved from solutions of UBr5 with 1 or more then 3 mol equivalents of acetonitrile in dichlormethane yielding UBr4 · CH3CN and UBr4 · 3CH3CN, respectively. These react with PPh4Br in acetonitrile affording (PPh4)2[UBr6] · 4CH3CN, the crystal structure of which was determined: 2663 reflexions, R = 0.050, space group P21/c, Z = 2, a = 981.8, b = 2010.1, c = 1549.3 pm, β = 98.79°. By reduction of uranium pentabromide with tetraethylammonium hydrogen sulfide in dichloromethane (NEt4)2[U2Br10] was obtained; (PPh4)2[U2Br10] formed from UBr4 and PPh4Br in CH2Cl2. Both compounds are extremely sensitive towards moisture and oxygen. The crystal structure of the oxydation product of the latter compound, (PPh4)2[U02Br4]· 2 CH2Cl2, was determined: 2163 reflexions, R = 0.083, space group C2/c, Z = 4, a = 2006.3, b = 1320.6, c = 2042,5 pm, β = 98.78°. Mean values for the UBr bond lengths in the octahedral anions are 266.2 pm for UBr6-, 276.7 pm for UBr62? and 282.5 pm for UO2Br42? 相似文献
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Kodibagkar VD Browning CD Tang X Wu Y Bowman RC Conradi MS 《Solid state nuclear magnetic resonance》2003,24(4):254-262
Powders of three hexagonal metal-hydrides or -deuterides are found to align in 4.4–8.3 T magnetic fields used for NMR. The field-alignment is unexpected, since all three systems have very small susceptibilities, as demonstrated by sharp NMR lines. The extent of alignment runs from nearly complete to barely detectable in ZrBe2(H,D)x, LuD3, and YD3, respectively. The preferred alignment direction in ZrBe2(H,D)x is with the crystallites’ c-axis perpendicular to B, while the c-axis and B tend to be parallel in LuD3 and YD3. The susceptibilities χ|| and χ are determined from bulk magnetization measurements in aligned ZrBe2H1.4 powder. The alignment must be considered for proper analysis of NMR spectra in these and related materials. 相似文献
6.
<正>Two new eudesmane derivatives were isolated from the leaves and flowers of Verbesina virginica,along with the known 6-O-β-E -p-coumaroyl-4α-hydroxyeudesmane(1).Their structures were determined as 6-O-β-Z-p-coumaroyl-4α-hydroxyeudesmane(2) and 6-O-α-E-p-coumaroyl-1β-4α-dihydroxyeudesmane(3) by spectroscopic methods. 相似文献
7.
A method is proposed for the analysis of optical devices with lossy metal layer by including an analytical formulation into the finite difference expressions. Losses of TM0 mode in an electro-optic switch for wavelength 1523 nm, exhibiting a sharp maximum of 37 dB are computed by this method. The results show very good agreement with the data obtained by the Mode Matching Method and Finite Difference Beam Propagation Method. 相似文献
8.
Matthias Conradi Gijs Ramakers Thomas Junkers 《Macromolecular rapid communications》2016,37(2):174-180
Benzaldehyde‐functional cellulose paper sheets have been synthesized via tosylation of cellulose (Whatman No 5) followed by addition of p‐hydroxy benzaldehyde. Via UV‐induced Paterno–Büchi [2+2] cycloaddition reactions, these aldehyde functional surfaces are grafted with triallylcyanurate, trimethylolpropane allyl ether, and vinyl chloroacetate. In the following, allyl‐functional polymers (poly(butyl acrylate), pBA, Mn = 6990 g mol−1, Đ = 1.12 and poly(N‐isopropyl acrylamide), pNIPAAm, Mn = 9500 g mol−1, Đ = 1.16) synthesized via reversible addition fragmentation chain transfer polymerization are conjugated to the celloluse surface in a UV‐induced grafting‐to approach. With pBA, hydrophobic cellulose sheets are obtained (water contact angle 116°), while grafting of pNIPAAm allows for generation of “smart” surfaces, which are hydrophilic at room temperature, but that become hydrophobic when heated above the characteristic lower critical solution temperature (93° contact angle). The Paterno–Büchi reaction has been shown to be a versatile synthetic tool that also performs well in grafting‐to approaches whereby its overall performance seems to be close to that of radical thiol‐ene reactions.
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CM Thaker S Rayaprol Krushna Mavani DS Rana MS Sahasrabudhe SI Patil DG Kuberkar 《Pramana》2002,58(5-6):1035-1039
The effect of simultaneous substitution of a fluctuating cation and a divalent cation in LaMnO3 perovskite modifies the properties of the material to exhibit large valence colossal magnetoresistance (CMR) effect. A good
example of these properties is (La1−2x
Pr
x
Ca
x
)MnO3 (LPCMO) type CMR material. In this communication it is reported that, with the increase in x (for x=0.1, 0.15, 0.2), the T
c varies between 100 and 120 K with improvisation in metal-insulator transition. Interestingly, resistance increases with x from few hundred ohms to few kilo ohms with corresponding decrease in the unit cell volume. The results of the studies using
X-ray diffraction (XRD), electrical resistivity, magnetoresistance and ac susceptibility measurements on LPCMO samples for
understanding the structural, transport and magnetic properties are discussed in detail. 相似文献