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11.
R. Murugesan P. Sami T. Jeyabalan A. Shunmugasundaram 《Journal of Chemical Sciences》1995,107(1):1-10
Bonding and redox properties of mono- and dititanium substituted 12-heteropolytungsto-phosphates and their complexes with
bivalent Mn, Co, Ni and Cu are studied by UV-Vis, ESR and cyclicvoltammetric techniques. The heteropoly blue analogue [TiIIITiIVW10PO40]8− is unstable and its presence in solution is proved by optical and ESR spectroscopy. ESR results reveal that the odd electron
is trapped on the titanium atom at 77 K. The optical electronegativity of Ti(III) in this heteropoly blue is estimated to
be 2.4 from the intervalence charge transfer (IVCT) bands. X-ray powder diffraction results show that the complexes K5MII[Ti2W10PO40].xH2O(MII = Cu or Mn) are isomorphous with K7[Ti2W10PO40].6H2O. Electronic spectroscopy indicates very high symmetry around the bivalent metal ion M in the K5MII[Ti2W10PO40].xH2O complexes. This high symmetry is confirmed in K5Cu[Ti2W10PO40] by the observation of dynamic Jahn-Teller (JT) distortion at 300 K and static JT distortion at 77 K. 相似文献
12.
二(邻香草醛缩丙醇胺)异硫氰酸根合锰(Ⅲ)的合成与晶体结构 总被引:2,自引:0,他引:2
本文报道了一个新配合物—二(邻香草醛缩丙醇胺根)异硫氰酸根合锰(Ⅲ)的合成及其晶体结构。配合物属于单斜晶系,空间群为P21/c,晶胞参数为:a=8.565(1), b=21.814(2), c=12.787(2)?, β=92.80(1)°。锰为六配位,在两个邻香草醛缩丙醇胺Schiff碱配体中,一个为三齿配体,另一个为双齿配体。NCS-离子以N在轴向上与锰发生配位,由于Jahn-Teller效应,其键长为2.193?。另外晶胞中存在着罕见的H……S-C≡N氢键。 相似文献
13.
14.
Studies of the vibrational spectra of matrix-isolated M+NO
3
–
ion pairs have been extended to glassy aprotic solvents. The deuterated form of the solvents DMSO, THF, and ACN have windows through the 7- nitrate ionv
3(e) mode infrared region, so it was possible to clearly observe the splitting of the degeneracy of this mode,v
3, produced by the contacting, but solvated, alkali metal cation. Primary attention has been directed to the extent to which this splitting is reduced relative to the argon matrix values. This reduction, which reflects electron-density transfer from the solvating molecules to the ion pairs, is comparable to that observed for H2O and NH3 matrices as the splitting is reduced to 20–35% of the argon-matrix values. The extent of reduction ofv
3 for the different solvents has been related to Gutmann's donicity number scale with the correlation holding well for solvent molecules of comparable size, DMSO, THF and DMF, but breaking down for the smaller linear ACN, apparently because of more molecules in the cation solvation sphere. The matrix data have also been used, through comparison with spectra for saturated liquid solutions of Li+NO
3
–
, to show that the contact ion pair is the dominant species in liquid THF and ACN, whereas the ions are largely solvent separated in DMSO. 相似文献
15.
硝酸根离子介质中偏钛酸钡的水热合成 总被引:1,自引:0,他引:1
以硝酸和钛酸四丁酯为原料,在240℃的碱液中成功地制备了四方相BaTiO3运用XRD、DSC和IR等技术碱度、硝酸根离子、钛源活性、填充度等因素对BaTiO3形成、粒度和物相的作用,KOH最适宜浓度为1.0mol/L,碱液中BaTiO3是BaO-TiO2体系中最稳定的物相,硝酸根离子参与了BaTiO3晶体的成核和生长,钛源的高活性和高填充度有利于四方BaTiO3的形成。 相似文献
16.
The hollandite Ba1Cs0.28Fe0.82Al1.46Ti5.72O16, which has been proposed for the cesium-specific conditioning, can be synthesized either by an alcoxyde or a dry route. In both cases, a two-step protocol is applied, i.e., a calcination at 1000 °C followed by a sintering at 1200 °C. After sintering, both synthetic processes lead to a tetragonal form. According to the X-ray diffraction (XRD) patterns collected at the barium and the cesium K absorption edges, the different positions of these two elements have been evidenced with a more centered position in the oxygen cubic site of the tunnel for Ba than for Cs. On the contrary, after calcination, the two synthetic routes yield different products. The alcoxyde route gives rise to a mixture of the aforementioned Cs- and Ba-containing tetragonal I4/m hollandite, a Cs-only-containing monoclinic I2/m hollandite and an unidentified phase with a weak coherence length containing only Ba. The dry route yields a single tetragonal hollandite material containing Ba and Cs slightly different in composition from the targeted compound. 相似文献
17.
聚合物微晶尺寸和晶格畸变是对聚合物材料性能有着重要影响的结构参数。本文介绍了应用X射线衍射方法测定聚合物微晶尺寸和结构畸变的几种方法:近似函数、次晶模型法、方差法、矩法。 相似文献
18.
1 INTRODUCTION In recent years, ABO3-type perovskite-like manganites, RE1xDxMnO3 (RE = rare earth ions, D = Ca2+, Sr2+, Ba2+ etc.), have inspired remarkable attention due to the colossal magnetoresistance (CMR) effects for fundamental and practical consideration [1, 2]. Since A- and B-site substitution can give rise to a large number of derivant compounds, fruitful structural, magnetic and transport properties would be expected in this family. As we have known, the ideal ABO3-typ… 相似文献
19.
Ramo Marceli Fernandes Gelson Manzoni de Oliveira Ernesto Schulz Lang Ezequiel M. Vzquez‐Lpez 《无机化学与普通化学杂志》2004,630(15):2687-2691
The reaction of tellurium(IV) tetrahalides with hydrochloric and hydrobromic acid leads to the formation of (H3O)2[TeX6], which reacts subsequently with (2‐Br‐C5NH5)+X‐ to afford (2‐Br‐C5NH5)2[TeCl6] ( 1 ) and (2‐Br‐C5NH5)2[TeBr6] ( 2 ). The structure of the complex salts were analysed by X‐ray diffractometry affording the centrosymmetric space groups P21/n (monoclinic, 1 ) and P1¯ (triclinic, 2 ). Interionic hydrogen bondings hold their lattices in bidimensional supramolecular arrays not yet described in the literature. The lone electron pair of the AX6E‐system of the hexahalotellurates [TeX6]2‐ (X = Cl, Br) seems to be fully delocalized since only small octahedral deviations were observed for the anionic species. The structures of the title compounds were refined with the Te atoms occupying sites with full point symmetry, approximately m3¯m. In both cases the Te atoms enclose centers of inversion and the octahedrally dynamic structures are enforced and stabilized along the supramolecular lattices by the crystal field of the 2‐Br‐pyridinium cations. 相似文献
20.
To investigate the solvation structure of the Cu(II) ion in liquid ammonia, ab initio quantum-mechanical/molecular-mechanical (QM/MM) molecular dynamics (MD) simulations were carried out at Hartree Fock (HF) and hybrid density functional theory (B3 LYP) levels. A sixfold-coordinated species was found to be predominant in the HF case whereas five- and sixfold-coordinated complexes were obtained in a ratio 2:1 from the B3 LYP simulation. In contrast to hydrated Cu(II), which exhibits a typical Jahn-Teller distortion, the geometrical arrangement of ligand molecules in the case of ammonia can be described as a [2 + 4] ([2 + 3]) configuration with 4 (3) elongated copper-nitrogen bonds. First shell solvent exchange reactions at picosecond rate took place in both HF and B3 LYP simulations, again in contrast to the more stable sixfold-coordinated hydrate. NH3 ligands apparently lead to strongly accelerated dynamics of the Cu(II) solvate due to the "inverse" [2 + 4] structure with its larger number of elongated copper-ligand bonds. Several dynamical properties, such as mean ligand residence times or ion-ligand stretching frequencies, prove the high lability of the solvated complex. 相似文献