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61.
A polyphosphide of the type (NaP)X 1 was obtained from red phosphorus and sodium in presence of small amounts of naphthalene in 1,2-dimethoxyethane as solvent. 1 reacts with alkyl halides in dependence on the kind of alkyl group with formation of different alkylcyclophosphanes. As definite compounds Me5P5 2 , Et5P5 3 (with not definite constitution), i-Pr4P4 4 and t-Bu4P4 5 could be isolated. 1 was identified by X-ray diffraction, 2 – 5 by means of their 1H, 13C, 31P n.m.r. and mass spectra. The molecular structure of 4 was identified by electron diffraction. 相似文献
62.
63.
在很高的温度和适宜的生长条件下,分别采用熔盐籽晶法和高温引上法生长了高质量的YAP、NAB、KTP、LN、BBO、SBN等多元氧化物单晶,它们具有优良的物理化学性能,严格的化学比,固定的组成与结构以及较好的化学均匀性和电子束轰击下的稳定性。广泛地用于激光和非线性光学领域。我们选用这些晶体为原材料研制电子探针定量分析的标准样品。经过测量和标定,这些单晶标样符合中华人民共和国国家标准GB 4930-85(电子探针显微分析标准样品通用技术条件)的规定。含有稀土元素的标样如NAB和YAP能发出绿色荧光,是电子显微术中理想的阴极发光材料。 相似文献
64.
Yoshihiko Nishimori Katsuhiko Kanaizuka Dr. Masaki Murata Dr. Hiroshi Nishihara Prof. 《化学:亚洲杂志》2007,2(3):367-376
Films of linear and branched oligomer wires of Fe(tpy)2 (tpy=2,2′:6′,2′′‐terpyridine) were constructed on a gold‐electrode surface by the interfacial stepwise coordination method, in which a surface‐anchoring ligand, (tpy? C6H4N?NC6H4? S)2 ( 1 ), two bridging ligands, 1,4‐(tpy)2C6H4 ( 3 ) and 1,3,5‐(C?C? tpy)3C6H3 ( 4 ), and metal ions were used. The quantitative complexation of the ligands and FeII ions was monitored by electrochemical measurements in up to eight complexation cycles for linear oligomers of 3 and in up to four cycles for branched oligomers of 4 . STM observation of branched oligomers at low surface coverage showed an even distribution of nanodots of uniform size and shape, which suggests the quantitative formation of dendritic structures. The electron‐transport mechanism and kinetics for the redox reaction of the films of linear and branched oligomer wires were analyzed by potential‐step chronoamperometry (PSCA). The unique current‐versus‐time behavior observed under all conditions indicates that electron conduction occurs not by diffusional motion but by successive electron hopping between neighboring redox sites within a molecular wire. Redox conduction in a single molecular wire in a redox‐polymer film has not been reported previously. The analysis provided the rate constant for electron transfer between the electrode and the nearest redox‐complex moiety, k1 (s?1), as well as that for intrawire electron transfer between neighboring redox‐complex moieties, k2 (cm2 mol?1 s?1). The strong effect of the electrolyte concentration on both k1 and k2 indicates that the counterion motion limits the electron‐hopping rate at lower electrolyte concentrations. Analysis of the dependence of k1 and k2 on the potential gave intrinsic kinetic parameters without overpotential effects: k10=110 s?1, k20=2.6×1012 cm2 mol?1 s?1 for [n Fe 3 ], and k10=100 s?1, k20=4.1×1011 cm2 mol?1 s?1 for [n Fe 4 ] (n=number of complexation cycles). 相似文献
65.
The subject of the investigations are precipitation zones, which grew as a result of chemical diffusion in AgPd30/CuSn6 bimetals. These precipitation zones have been characterized by metallography, electron probe microanalysis and x-ray diffraction. The growth of precipitation zones in the plating layer and in the substrate layer in dependence on time have been determined. The use of x-ray diffraction alone for the identification of the precipitates could not supply satisfying results in every case. This problem was solved by the application of electron probe microanalysis using a correction method, which allows the estimation of the chemical composition of small particles.Dedicated to Professor Dr. rer. nat. Dr. h. c. Hubertus Nickel on the occasion of his 65th birthday 相似文献
66.
Lingjia Xu Liangliang Zhu Shi Wu Xiaopeng Chen Qiwen Teng 《Central European Journal of Chemistry》2006,4(4):732-742
Supermolecular complexes formed by oligophenyleneethynylene derivatives and isophthalic acid were studied using AM1 method
to obtain binding energy. Electronic spectra and IR spectra of the complexes were calculated by INDO/CIS and AM1 methods based
on AM1 geometries. Results indicated that the dimer could be formed by the monomers via hydrogen bonding because of the negative
binding energy. Binding energy of the complexes was affected by electronegativity and steric effects of the substituents.
The first UV absorptions and IR frequencies of N-H bonds of the complexes were both red-shifted compared with those of the
monomers. The complexes could bind small molecules via hydrogen bonds, resulting in the change in UV absorptions and an increase
in IR frequencies of N-H bonds. 相似文献
67.
Five different structures of CH5
+ and one structure of CH5
– are calculated using a gaussian basis both in the SCF approximation and with the inclusion of electron correlation in the independent electron pair approximation (IEPA). While on SCF level the C
sstructure of CH5
+ has to lowest energy, the energy difference between the C
sand C
2vstructures becomes negligible if correlation is included. In contrast to this the approach of a proton to CH4 at large and intermediate distances is most favorable towards a corner of the CH4 tetrahedron which means a structure. The decomposition of CH5
+ into CH3
+ and H2 requires 20kcal/mol on SCF level and 40 kcal/mol if correlation is included. 相似文献
68.
A new mechanism is suggested for the anionic polymerization of isoprene. The key moment of this mechanism is thermal electron excitation of the complex of a living polymer with a monomer to the low lying S1 (T1) state involving a charge (electron) and (Li+) cation transfer from the terminal unit to the monomer molecule. It is stated that the probability of chemical bonding depends on the spin density on the radical centers of reactant molecules and on the geometry of the reaction complex. The semiempirical AM1 and ab initio 6-31G* quantum-chemical calculations revealed strong interaction for the ground electronic state of the complex (5-10 kcal/mole) and low energies of the excited triplet levels (<10 kcal/mole). 相似文献
69.
Poly(methyl methacrylate) (PMMA)/silica/titania ternary nanocomposites with covalent bonding interaction between polymer and inorganic phases have been prepared using a novel non-hydrolytic sol-gel method. Transmission electron microscope (TEM) image of silica/titania binary inorganic component indicates a core-shell-like structure. Scanning electron microscope (SEM) images suggest that the well dispersed silica/titania particles in the hybrid are on the nanometer-scale. The transparencies of nanocomposites are maintained in visible region while the absorption band in ultraviolet (UV) region is red shifted with increasing inorganic content. The thermogravimetric analysis (TGA) results show that the thermal stability of PMMA copolymer increases dramatically with the addition of silica/titania moieties both in nitrogen and in air. 相似文献
70.
The reaction of M2(O2CBu(t))4 (M = Mo, W) with a dicarboxylic acid in toluene yields compounds of general formula [M2]-O2C-X-CO2-[M2] ([M2] = M2(O2CBu(t))3; X = conjugated spacer). The M2 units are electronically coupled via interactions between the M2 delta and dicarboxylate pi* orbitals, and the magnitude of this coupling is revealed by electronic structure calculations and spectroscopic data. These compounds show intense metal to ligand charge transfer (MLCT) absorptions in the visible region of the electronic spectrum that are temperature and solvent dependent. Evidence of electronic coupling is seen in their cyclic voltammograms, which show two successive one-electron oxidations. The extent of electronic coupling in the mixed valence radical cations [M2]-O2C-X-CO2-[M2]+, generated by oxidation with one equivalent of AgPF6 or FeCp2PF6, is evaluated by EPR and UV-vis-NIR spectroscopic data, and delocalized behavior is observed in compounds with W2 units separated by up to 13.6 angstroms. The simplicity of the frontier M2 orbital interactions with the bridge pi orbitals provides a convenient system with which to study electron transfer in mixed valence systems, as compared to the extensively studied, but more complicated, dinuclear t(2g)6/t(2g)5 mixed valence compounds. Oligomeric and polymeric compounds incorporating M2 units have also been synthesized, having general formula [M2(O2CR)2(O2C-Thio-CO2)]n (Thio = n-hexyl substituted ter- and quinque-thiophenes). They can be deposited as thin films by spin coating, and show photoluminescence and electroluminescence. These metallo-polythiophenes show potential for application in electronic materials. ( 相似文献