The ligand-exchange equilibria in cyclopentadienyl and metal carbonyl complexes of lanthanum have been qualitatively studied by139La NMR spectroscopy: 2X1X2X3La X1X22 La + X1X3, La, where X1=X2=Cp, X3=I; X1=X2 = 1, 3-(Me3Si)2C5H3, X3=Cl; X1=Ru(CO)2Cp; X2=Cp, X3=I. Similar equilibria are typical of the coordination chemistry of light lanthanides.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 578–581, March, 1993. 相似文献
The stability constans,
1, of each monochloride complex of Eu(III) have been determined in the methanol and water mixed system with 1.0 mol·dm–3 ionic strength using a solvent extraction technique. The values of
1 increase with an increase in the mole fraction of methanol (XS) in the mixed solvent system when 0XS0.40. The, distance of Eu3+–Cl– in the mixed solvent system was calculated using the Born-type equation and the Gibbs' free energy derived from
1. Calculation of the Eu3+–Cl– distance and the preferential solvation, of Eu3+ by water proposed the variation of the outersphere complex of EuCl2+ as follows: (1) [Eu(H2O)9]3+Cl–, [Eu(H2O)8]3+Cl– and [Eu(H2O)7(CH3OH)3+Cl– inXS0.014, (2) [Eu(H2O)8]3–Cl– and [Eu(H2O)7(CH3OH)]3+Cl– in 0.014<XS<0.25 and (3) [Eu(H2O)7(CH3OH)]3–Cl– and [Eu(H2O)6(CH3OH)[23+Cl– in 0.25<XS0.40. 相似文献
The structure and the pentacoordination effect in quasimonocyclic models of IVa group atranes were investigated by ab initio[MP2 (full) /6-311+G **] and the density functional [B3LYP/6-311+G **] quantum chemical calculations. The calculations revealed considerable stabilization of the quasimonocyclic conformations relative to their free-of-strain trans-s-transconformations, which is caused by the formation of secondary (R)XN (X=C, Si, Ge) bonds of the hypervalent type. The strength of the intramolecular (R)XN coordination increases in the order X=C, Si, Ge. The nature of attractive (R)XN coordination is determined by donor-acceptor interaction of the nitrogen lone electron pair and antibonding orbital which primary localize at the X-R bond. Energy of X ··· N (X=Si, Ge) contact is about 3-7 kcal mol-1. 相似文献
Solid polymer electrolyte films were prepared by adding Al2O3 particles to poly(vinylpyrrolidone)-MgCl2 ? 6H2O salt using solution cast technique. Various analytical techniques have been applied to characterize the prepared polymer films such as XRD, SEM, UV–Vis spectroscopy and AC conductivity. The structural analysis of pure poly(vinylpyrrolidone) complexed with MgCl2 ? 6H2O salt showed orthorhombic lattice structure indicating its semi-crystalline nature. SEM analysis reveals the heterogeneous phase of nanocomposite polymer electrolyte systems. The conductivity of Al2O3 doped poly(vinylpyrrolidone) based solid polymer electrolyte was found to be 1.22 × 10–6 S/cm at room temperature for 85: 15 weight composition. Electrochemical cell has been fabricated with the configuration Mg+/(PVP + MgCl2 ? 6H2O + Al2O3)/(I2 + C + electrolyte) and its discharge characteristics were studied for a constant load of 100 kΩ. Various cell parameters such as open-circuit voltage, short circuit current, energy density and power density were calculated for the prepared samples. 相似文献
The influence of co-ions in the eluent on the separation factor () of lithium isotope separation has been studied by ion exchange chromatography. A strongly acid cation exchange resin (Dowex 50W-X8) was used for the separation of lithium isotopes. The co-ions used in eluent were H+, K+, Ba2+, Cu2+, Al3+ and Cr3+ as their chlorides. From the experiments, it was found that6Li was enriched in the resin phase and7Li in solution phase. At the same distribution coefficient (Kd=30), the separation factor increased linearly with the charge of co-ion (=1.0022 to 1.0039). 相似文献
Dynamics of refractory atom reactions have been studied with a crossed beam apparatus combining two pulsed, supersonic molecular beam sources, a pulsed UV laser for creating the refractory atoms in the gas phase by laser ablation, and a pulsed dye laser to probe the reaction products by laser-induced fluorescence. Examples of the A1(2Pj) + O2(X3∑g)→ A10(X2∑+) + O(3Pj), Mg(1So) + N2O(X1∑+) → MgO(X1∑+,a3Π) + N2(X1∑g+) andC(3Pj) + NO(X2Πr) → CN(X2∑+) + 0(3Pj) systems are given. Comparisons with the studies performed using the conventional steady-state beam approach are made. 相似文献
Spectral and kinetic parameters were studied for phosphine-bipyridyl ruthenium(II) complexes, namely, cis-[Ru(Bipy)2(PPh3)X](BF4), cis-[Ru(Bipy)(Dppe)X2], and cis-[Ru(Bipy)(Dppene)X2] (where Bipy is 2,2"-bipyridyl, PPh3is triphenylphosphine, Dppe is 1,2-bis(diphenylphosphino)ethane, and Dppene iscis-1,2-bis(diphenylphosphino)ethylene; X = CN–, NO2–), in the frozen (77 K) alcohol glasses (EtOH–MeOH, 4 : 1). The energies of the singlet and triplet metal-to-ligand charge transfer states d(Ru) *(Bipy) were found to increase in the order [Ru(Bipy)2X2] < [Ru(Bipy)2(PPh3)X]+< [Ru(Bipy)(Dppe)X2] < [Ru(Bipy)(Dppene)X2]. The luminescence quantum yields and the rate constants of the nonradiative deactivation of the lowest excited state 3MLCT increase in the same order. 相似文献
Time-resolved light scattering was employed to investigate kinetics of phase separation in mixtures of poly (ethylene glycol monomethylether) (PEGE)/poly (propylene glycol) (PPG) oligomers. Phase diagrams for PEGE/PPG of varying molecular weights were established by means of cold point measurements. The oligomer mixtures reveal an upper critical solution temperature (UCST). Several temperature quench experiments were carried out with a 60/40 PEGE/PPG blend by rapidly quenching from a single phase (69°C) to two-phase temperatures (66–61°C) at 1°C intervals. As is typical for oligomer mixtures, the early stage of spinodal decomposition (SD) was not detected. The kinetics of phase decomposition was found to be dominated by the late stage of SD. Time-evolution of scattering intensity was analyzed in accordance with nonlinear and dynamical scaling theories. The time dependence of the peak intensity Im and the corresponding peak wavenumber qm was found to follow the power-law {Im(t)? tα, qm(t)? t-β} with the values of α = 3 ± 0.3 and β = 1 ± 0.2, which are very close to the values predicted by Siggia. This process has been attributed to a coarsening mechanism driven by surface tension. In the temporal scaling analysis, the structure function reveals university with time, suggesting self-similarity. Phase separation dynamics in 60/40 PEGE/PPG resembles the behavior predicted for off-critical mixtures. 相似文献
Ion mobility mass spectrometry (IMS-MS) techniques were used to generate a database of 2288 collision cross sections of transition-metal-coordinated tryptic peptide ions. This database consists of cross sections for 1253 [Pep + X]2+ and 1035 [Pep + X + H]3+, where X2+ corresponds to Mn2+, Co2+, Ni2+, Cu2+, or Zn2+. This number of measurements enables the extraction of structural trends for transition-metal-coordinated peptide ions. The range of structures and changes in collision cross sections for X2+-coordinated species (compared with protonated species of the same charge state) is similar to Mg2+-coordinated species. This suggests that the structures are largely determined by similarities in cation size with differences among the cross section distributions presumably caused by X2+ interactions with specific functional groups offered by the residue R-groups or the peptide backbone. Cross section contributions for individual residues upon X2+ solvation are assessed with the derivation of intrinsic size parameters (ISPs). The comparison of the [Pep + X]2+ ISPs with those previously reported for [Pep + Mg]2+ ions displays a lower contribution to the cross section for His, carboxyamidomethylated Cys, and Met, and is consistent with specific metal-residue interactions identified within protein X-ray crystallography databases.
