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101.
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103.
Miroslav Bo
a Duan Valigura Ingrid Svoboda Hartmut Fuess Wolfgang Linert 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):838-839
The title compound, C19H14N5+·ClO4?·H2O, contains planar C19H14N5+ cations, perchlorate anions and water molecules. The two closest parallel cations (plane‐to‐plane distance of 3.41 Å), together with two neighbouring perchlorate anions and two water molecules, form an electrically neutral quasi‐dimeric unit. Two acidic H atoms of the cation, both H atoms of the water molecule, the N atoms of the imidazole rings and three of the four O atoms of the perchlorate anion are involved in the hydrogen‐bonding network within the dimeric unit. The remaining third acidic H atom of the imidazole rings and the water molecules complete a two‐dimensional network of hydrogen bonds, thus forming puckered layers of dimers. The angle between the planes of two neighbouring dimeric units in the same layer is 33.25 (3)°. 相似文献
104.
Shifts of current free electrochemical potentials have been measured during and after mechanical deformation of silver electrodes in 5 · 10–4 molar electrolyte solutions of water, dimethylsulfoxide, propylene carbonate, ethylene sulfite and acetonitrile. The potential changes and their relaxations were investigated depending on the pretreatment of the electrolytes. The plastic deformation of the electrodes produced potential shifts towards positive values in the range of millivolts. The potential shifts were interpreted in terms of the slipping of (111) planes from the bulk electrode to the interface. It is assumed that changes in microcrystalline surface structures may account for the high exchange current densities observed. 相似文献
105.
A new cobalt(II) complex of 1-vinylimidazole (vinim) has been synthesized as the perchlorate salt and structurally characterized. The molecular structure of the complex exhibits six coordination in which the geomety is a distorted octahedron. The vinylimidazole ring is coordinated through the imidazole nitrogen, as expected from earlier spectroscopic studies of related adducts. The space group is P21/n, with a = 8.512(2), b = 13.857(2), c = 16.146(2) Å, = 96.30(1)°, V = 989.31 Å3, and Z = 2. 相似文献
106.
Reduction of Cd2+ at the dropping mercury electrode in solutions of 1, 3, 5-trihydroxybenzene was carried out in nonbuffer solutions of 0.1 M NaClO4. The polarogram consists of two waves, the first wave can be taken in quantitative determination of Cd2+ in solutions containing 3.5 mM 1, 3, 5-trihydroxybenzene in 0.1 M NaClO4. Mn2+ produces single well-defined diffusion controlled irreversible wave whose half-wave potential shifts to a more negative value with increasing 1, 3, 5-trihydroxybenzene. Me(II) forms two weak complexes, MX1 and MX2 at 25°. The behaviour of this metal ions is summarized. 相似文献
107.
Summary A series of transition metal complexes [M(bzimpy)2](ClO4)2 (M=Mn2+, Fe2+, Co2+, Ni2+, Zn2+;bzimpy=2,6-bis(benzimidazol-2-yl)pyridine) was synthesized and characterized by elemental analysis, UV-Vis and far-IR spectroscopy. The electronic spectra of [Ni(bzimpy)2](ClO4)2 in solution and solid state reveal a ligand field splitting parameter 0 in the range of 11470 cm–1 to 11840 cm–1. The simultaneous existence of two species with distinct spin state is found for [Fe(bzimpy)2](ClO4)2 by means of variable temperature far-IR measurements. Assignments of the observed far-IR bands are given on the basis of the investigations of the variation of the metal ion in [M(bzimpy)2](ClO4)2.This paper is dedicated to Professor Ulrich Wannagat on the occasion of his 70th birthday with warmest personal wishes. 相似文献
108.
Andrei B. Koudriavtsev Wolfgang Linert 《Monatshefte für Chemie / Chemical Monthly》2006,137(4):433-447
Summary. The approach of molecular potentials describing the shape of transition curves of spin crossover in the solid state developed
earlier has been extended to many-body interactions characterized by the Axilrod-Teller potential. An improved procedure for the minimization of energy developed for this case is presented. Calculations for systems
involving Lennard-Jones, electric dipole–dipole, and dispersive Axilrod-Teller triple interactions yield non-zero asymmetries of splittings in expanded/compressed systems alone. The excess energy is unaffected
by the Axilrod-Teller potential. Triple interactions of the Axilrod-Teller type thus increase the sensitivity of a transition curve towards compression.
Another approach presented employs the deviations of molecules from positions of mechanical equilibrium set up by the known
binary potential. In the approximation of small perturbations these deviations are proportional to the gradients of many-center
potentials. This allows one to parametrically define non-ideality parameters as functions of gradients of triple potentials
of unknown types. Employing regularization bounds an adequate parameterization of experimental transition curve of spin crossover
has been achieved in terms of parameters of Lennard-Jones potential and relative deviations of molecules from the position of mechanical equilibrium. 相似文献
109.
W. Linert M. Enamullah V. Gutmann R. F. Jameson 《Monatshefte für Chemie / Chemical Monthly》1994,125(6-7):661-670
Summary Transition metal complexes of the composition [Fe(4-X-bzimpy)2](ClO4)2 [bzimpy = 2,6-bis-(benzimidazol-2-yl)pyridine and X=H, OH, Cl] show thermally accessible spin-crossover behaviour in solution that depends on both the ligand and the solvent.1H-NMR spectroscopy and UV-visible spectroscopy measurements suggest that ligand substituent effects, solvent donor-acceptor properties and hydrogen-bonding may be employed to fine-tune the ligand field strength and hence to affect the spin-crossover behaviour. The ligand substitution changes in solution are reflected by the magnetic data (X=H:exp=2.50 B; X=OH:exp=4.20 B and X=Cl:exp=4.30 B at 294 K in MeOH), and by the shift of metal-to-ligandcharge-transfer band (X=H, =557 nm; X=OH, =520 nm; X=Cl, =500 nm). [Fe(bzimpy)2](ClO4)2 exhibits a pronounced spin-crossover equilibrium (1A1 5T2) in solution (K
sc=0.26 at 293 K; exp=1.30 3.40 B for 213 328 K in MeOH). A small variation of magnetic moments of [Fe(4-OH-bzimpy)2](ClO4)2 (exp=3.77 4.73 B at 220 332 K) might indicate either the existence of (temperature dependent) hydrogen bonding between the ligand and solvent molecules or a temperature dependent variation in the population of the5Eg sublevel. The presence of strong donor solvents (DN 30) shifts the spin-state of the complexes.In course of absence from the Chemistry Department, Jahangirnagar University, Dhaka, Bangladesh 相似文献
110.