三氟化硼乙醚溶液中聚(二苯并呋喃)的电化学合成

在三氟化硼乙醚-硫酸混合电解质溶液中,二苯并呋喃直接阳极氧化聚合可以获得高质量聚(二苯并呋喃)膜.二苯并呋喃在纯三氟化硼乙醚中的起始氧化电位为1.30 VvsSCE,远低于单体在0.1 mol.L-1Bu4NBF4乙腈溶液中的起始氧化电位(2.14 V).硫酸的加入进一步降低了二苯并呋喃的氧化电位.在三氟化硼乙醚-硫酸混合电解质溶液中,二苯并呋喃的起始氧化电位可降低至1.0 V;同时在该体系中获得的聚(二苯并呋喃)膜具有良好的电化学性质和荧光性质.     

Synthesis,Crystal Structure,and High Temperature Behavior of Zr3N4

A red-brown zirconium nitride was prepared by ammonolysis of ZrCl₄. Chemical analysis leads to a composition of Zr₃N₄. It is not possible to distinguish between the space groups Pnam and Pna2₁ in the case of Zr₃N₄ using powder methods. The lattice constants are: a = 972.94(5) pm, b = 1081.75(6) pm, c = 328.10(1) pm (Z = 4). X-ray powder diffraction data were used for structure refinement. The high temperature behavior was investigated with in situ XRD methods. Zr₃N₄ decomposes into ZrN and nitrogen gas at temperatures above 800°C.     

Synthesis of Nanocrystalline Zr3N4 and Hf3N4 Powders from Metal Dialkylamides

A simple process to synthesize Zr₃N₄ and nitrogen‐rich Hf₃N₄ powders via ammonolysis of metal dialkylamides, i.e. Zr(NEt₂)₄ and Hf(NEt₂)₄, at temperatures below 700 °C is presented. The obtained nitrides have a rhombohedrally distorted NaCl‐type structure, which has previously been reported only for nitrogen‐rich films of these nitrides. Regardless of the atmosphere (N₂ and He), the Zr₃N₄ starts to decompose above about ～ 650 °C and achieves the highest decomposition rate at about 900 °C, finally yielding the mononitride ZrN. Both Zr₃N₄ and Hf₃N₄ powders are nanocrystalline with the crystal size of about 2 nm.     

Deep Oxidation of Methane on a Pt/Si3N4 Catalyst

We have studied platinum catalysts supported on silicon nitride Si₃N₄ in the process of deep oxidation of methane. We have used transmission electron microscopy and X-ray photoelectron spectroscopy to study the surface properties of the Pt/Si₃N₄ samples before and after the catalytic reaction. We have established that the metallic platinum particles in freshly prepared systems are characterized by average sizes of 1.7-5.3 nm, while after the catalytic reaction we observe formation of Pt crystallites up to 30-70 nm in size. We hypothesize that the observed deactivation of platinum catalysts in deep oxidation of methane is connected with crystallization of the metallic particles and their entrainment with the reaction products during catalysis.     

Thermal behavior of nitrided TiO2/In2O3 by TG–DSC–MS combined with PulseTA

TiO₂/InN (In/(Ti + In) = 6.5:100 mol) was prepared by nitridation of TiO₂/In₂O₃ by NH₃ at 580 °C for 8 h. Only the anatase TiO₂ phase was detected in the XRD measurements. The highly dispersed InN clusters on the surface of anatase TiO₂ nanocrystals were beyond the detection limit of XRD. In order to confirm the existence of InN in the products of nitridation, thermogravimetry–differential scanning calorimetry–mass spectrometry (TG–DSC–MS) coupling techniques were used for a simultaneous characterizing study of the changes of mass, enthalpy and determination of the evolved gases during the thermal decomposition of the InN and the nitrided TiO₂/In₂O₃ samples. Moreover, pulse thermal analysis (PulseTA) was combined with TG–DSC–MS for the quantitative calibration of the evolved nitrogen formed during the thermal decomposition of the InN and the nitrided TiO₂/In₂O₃. The applied technique enabled identification and quantification of the InN in the products of the nitridation of TiO₂/In₂O_3.     

Magnetochemistry of boron hydride structures. Empirical aspects

The reviews and monographs on magnetochemistry of boron compounds are discussed. The structural peculiarities of borane derivatives relevant to magnetochemical calculations of diamagnetic contributions are are considered. Experimental measurements of diamagnetic susceptibility for deltahedral B₁₀H ₁₀ ^2– and B₁₂H ₁₂ ^2– cluster closo-anions were used to derive the diamagnetic atomic increments of the B atoms (_B) with coordination numbers 5 and 6. The atomic increments _B thus obtained were used to calculate molecular diamagnetic susceptibility _M of borane derivatives. Diamagnetic susceptibility _M was measured and calculated for the series of borane derivatives B_nH _n ^2– and B₁₀H₁₂L₂ (L is a Lewis base)and cobalt(III) derivatives of ortho-carborane(12) [(B₉C₂H₁₁)₂Co_n(B₈C₂H₁₀) _n–1] ^n–. Diamagnetic increments were obtained for |B₁₀H₁₂| fragments and (B₉C₂H₁₁)^2– and (B₈C₂H₁₀)^4– ligands. The increments can be employed for calculating _M for novel compounds. The calculated values of _M coincide with the experimental values within 2%–6%.Original Russian Text Copyright © 2004 by V. V. Volkov and V. N. IkorskiiTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 729–740, July–August 2004.This revised version was published online in April 2005 with a corrected cover date.     

Three-coordinate organoboron compounds BAr2R (Ar = mesityl, R = 7-azaindolyl- or 2,2'-dipyridylamino-functionalized aryl or thienyl) for electroluminescent devices and supramolecular assembly

Eight novel three-coordinate boron compounds with the general formula BAr(2)L, in which Ar is mesityl and L is a 7-azaindolyl- or a 2,2'-dipyridylamino-functionalized aryl or thienyl ligand, have been synthesized by Suzuki coupling, Ullmann condensation methods, or simple substitution reactions (L = p-(2,2'-dipyridylamino)phenyl, 1; p-(2,2'-dipyridylamino)biphenyl, 2; p-(7-azaindolyl)phenyl, 3; p-(7-azaindolyl)biphenyl, 4; 3,5-bis(2,2'-dipyridylamino)phenyl, 5; 3,5-bis(7-azaindolyl)phenyl, 6; p-[3,5-bis(2,2'-dipyridylamino)phenyl]phenyl, 7; 5-[p-(2,2'-dipyridylamino)phenyl]-2-thienyl, 8). The structures of 1, 3, and 5-7 have been determined by X-ray diffraction analyses. These new boron compounds are bright blue emitters. Electroluminescent devices using compound 2 or 8 as the emitter and the electron-transport layer have been successfully fabricated. Molecular orbital calculations (Gaussian 98) have established that the blue emission of compounds 1-8 originates from charge transfer between the pi orbital of the ligand L and the p(pi) orbital of the boron center. The ability of these boron compounds to bind to metal centers to form supramolecular assemblies was demonstrated by treatment of compound 2 with Zn(O(2)CCF(3))(2), which generated a 1:1 chelate complex [2.Zn(O(2)CCF(3))(2)] (10), and also by treatment of compound 4 with AgNO(3), yielding a 2:1 coordination compound [(4)(2).Ag(NO(3))] (11). In the solid state, compounds 10 and 11 form interesting head-to-head and tail-to-tail extended structures that host solvent molecules such as benzene.     

Nitridsulfidchloride der Lanthanide: II. Der Formeltyp M6N3S4Cl (M = La?Nd)

Nitride Sulfide Chlorides of the Lanthanides. II. The Composition M₆N₃S₄Cl (M = La? Nd) The oxidation of the “light” lanthanides (M = La? Nd) with sulfur and NaN₃ in the presence of the chlorides MCl₃ yields chlorine-poor nitride sulfide chlorides with the composition M₆N₃S₄Cl when appropriate molar ratios of the reactants are used. Additional NaCl as a flux secures complete and fast reactions (7 d) at 850°C in evacuated silica vessels as well as single-crystalline products (red-brown needles). The crystal structure was determined from X-ray single crystal data for the limiting representatives La₆N₃S₄Cl (orthorhombic, Pnma (no. 62), Z = 4, a = 1159.7(4), b = 410.95(7), c = 2756.8(9)pm, R = 0.030, R_w = 0.027) and Nd₆N₃S₄Cl (a = 1137.1(3), b = 399.34(6), c = 2687.6(9)pm, R = 0.034, R_w = 0.033). Guinier powder data revealed the cerium and praseodymium analogues to be isotypic. The crystal structure exhibits two different chains of connected [NM₄] tetrahedra which are commensurate in translation. Six crystallographically different M³⁺ are present, two of them (M1 and M2) build up the chain [(N1)(M1) · (M2)]³⁺ together with (N1)^3? by cis-edge connection of tetrahedra. The four remainders (M3? M6) arrange as pairs [N₂M₆] of edge-shared [NM₄] tetrahedra with (N2)^3? and (N3)^3? which are further connected via four vertices to form the [(M5)(N-2){(M3)_(1+1)/(1+1)(M4)_(1+1)/(1+1))}^e(N3)(M6)]⁶⁺ double chain. Bundled along [010] like a closest packing of rods, both types of chains are held together by five crystallographically different but by X-ray diffraction indistinguishable anions S^2? (S1? S4) and Cl^? adjusting the charge balance in a molar ratio of 4:1.     

Investigation of the boron nitride/polybenzoxazine interphase

The influence of a hexagonal boron nitride powder surface on the polymerization of a benzoxazine monomer is examined by differential scanning calorimetry (DSC). By varying the thickness of the benzoxazine coatings on boron nitride particles, a distinct influence of the surface substrate on the polymerization reaction could be observed. At a coating thickness calculated to be on the order of a monolayer, the heat of reaction is reduced, while the exothermic peak temperature and peak width at half height are increased relative to that of the neat resin values. The reduced heat of reaction and increased exothermic peak temperature indicate that the boron nitride surface is inhibiting the benzoxazine polymerization reaction. In the intermediate coating thickness region, the heat of reaction increases and the exothermic peak temperature and peak width at half height decrease with increasing coating thickness. With even thicker coatings, the heat of reaction and exothermic peak temperature and peak width at half height reach values corresponding to that of the neat resin and no longer change with thickness. In addition, the influence of surface treated boron nitride particles on the thermal polymerization behavior, as well as the effect of the surface treatment on the viscosity, dynamic mechanical properties, and flexural properties of the filled composites are also investigated. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2360–2372, 1999     

Darstellung,Kristallstruktur und IR-spektroskopische Untersuchung von Phosphor(V)-nitrid-imid,HPN2

Preparation, Crystal Structure, and IR-spectroscopic Investigation of Phosphorus Nitride Imide, HPN₂ Pure and fine crystalline phosphorus nitride imide (HPN₂) is obtained by heterogeneous ammonolysis of P₃N₅ with gaseous NH₃ (T = 580°C, p = 30 bar, 6 d). X-ray powder diffraction data has been used to refine the crystal structure of HPN₂ by the Rietveld full-profile technique (I4 2d; a = 461.82(2) pm, c = 702.04(3) pm; Z = 4; 41 reflections observed, 17° < 2Θ < 125°, CuKα₁, germanium monochromator; R(wp) = 0.072, R(I,hkl) = 0.048). In the solid HPN₂ contains a three-dimensional framework of corner-sharing PN₄-tetrahedra (P N: 159.9(4) pm; P N P: 130.1(4)°. The hydrogen atoms are covalently bonded to half of the nitrogen atoms. The IR spectrum exhibits six vibrational modes v(N H): 3224; v_as(PNP): 1330, 1223; v_as(PNHP): 971, 901: δ(PNP): 531 cm⁻¹).