Sorption and Separation of Optical Isomers of 2-Butanol by Chiral Porous Coordination Polymers

Theoretical and Experimental Chemistry - It was shown that porous coordination polymers (PCPs) of 3d metals containing chiral centers in fragments of deprotonated (S)-lactic and (R)-aspartic acid...     

Nature and strength of weak intermolecular interactions with metal atoms in crystals of square-planar nickel(<Emphasis Type="SmallCaps">ii</Emphasis>) complexes

The results of geometric analysis of 588 crystal structures of square-planar nickel complexes containing short intermolecular Ni…X contacts (X is a non-metal atom) are reported. The frequency of occurrence of Ni…X interactions of a particular type was evaluated depending on the nature of the X atom and geometric characteristics. The promolecular functions RDG and sign(λ₂)?ρ(r) were used to analyze the character of Ni…X interactions in attractive/repulsive terms. The relative strength of these interactions was determined as the function of the nature of the X atom and the direction of charge transfer.     

Copper(II) complex with salicylaldehyde <Emphasis Type="Italic">N</Emphasis>-(2-salicylideneiminoglutaryl)hydrazone: Synthesis and structure

A copper(II) complex with salicylaldehyde N-(2-salicylideneiminoglutaryl)hydrazone (H₄L) of the formula [Cu₂L · 2Py]₂ · 8H₂O (I) was obtained and characterized by X-ray diffraction. The crystals are monoclinic, space group P2₁, a = 13.0663 Å, b = 16.5553 Å, c = 17.7650 Å, β = 97.9420°; Z = 4. The complex is tetranuclear with a “dimer-of-dimers” structure in which the copper cations of two binuclear subunits are linked by phenoxy bridges. The EPR spectra of solutions of complex I show a superposition of two signals of four HFS lines (g ₁ = 2.111, a ₁ = 56.8 × 10^?4 cm^?1 and g ₂ = 2.183, a ₂ = 71.0 × 10^?4 cm^?1).     

X-ray photoelectron spectra of heterometallic 3<Emphasis Type="Italic">d</Emphasis>-metal carboxylate complexes

The electronic structure and magnetic states in the heterometallic hexanuclear complex Mn₄^IIFe₂^III (μ₄-O)₂(Piv)₁₀ · MeCN₄ have been studied by X-ray photoelectron spectroscopy (XPS). The substitution of two Mn atoms for two Fe atoms in the hexanuclear complex was found to have an effect on the patterns of iron and manganese X-ray photoelectron spectra. XPS data are evidence of the high-spin paramagnetic state of Mn^II and Fe^III atoms, as well as of the ligand-metal charge transfer upon complex formation. In the heteroatomic complex, the degree of bond covalence increased for both the manganese and iron atoms. The results obtained are in good agreement with X-ray diffraction data.     

Binuclear heterometallic {M-Ln} pivalate complexes (M = Co, Ni, Cu; Ln = Sm, Gd): synthesis, structure, and thermolysis

Binuclear heterometallic complexes (??²-bpy)CoLn(Piv)₅(H₂O), (??²-bpy)NiLn(Piv)₅(H₂O), and (??²-bpy)CuLn(Piv)₅(HPiv) (Ln = Sm or Gd, Piv- is the pivalate anion) were synthesized. A comparative study of the structural characteristics and the thermolysis of the resulting compounds was performed.     

Synthesis, structure, and magnetic properties of heterometallic trinuclear complexes {MII��LnIII��MII} (MII = Ni, Cu; LnIII = La, Pr, Sm, Eu, Gd)

Trinuclear heterometallic complexes containing the {M₂Ln(Piv)₆(NO₃)} (M^II = Ni, Cu; Ln^III = Nd, Pr, Sm, Eu, Gd; Piv^? is the anion of pivalic acid) and {Cu₂Ln(Piv)₈)]^? (Ln^III = Eu, Gd) metal cores were synthesized, their structures and magnetic properties were studied. For the most compounds, it was shown that their magnetic properties can be interpreted taking no interaction of the 3d-metal ions and a lanthanide into account. Ferromagnetic exchange interactions were found to exist between the unpaired electrons of the paramagnetic centers in the exchange clusters of the gadolinium-containing heterometallic complexes {M-Gd-M} (M = Ni or Cu).     

CdS nanoparticles in porous silicate glasses: energy characteristics, photocatalytic activity, and the effect of silver ion doping

Energy diagrams were constructed for CdS nanoparticles doped with silver ions and incorporated into silicate matrices, which are new nanostructural materials. The effect of the amount of silver introduced on the efficiency of the photocatalytic evolution of hydrogen from aqueous sulfide-sulfite solutions was demonstrated, and the interrelationship between the photocatalytic activity of these materials and their energy characteristics was established. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 34, No. 6, pp. 360–365, November–December, 1998.     

Stochastic model of tilting mode in nuclear fission

A model of induced nuclear fission was developed with consideration of thermodynamically fluctuating orientation degree of freedom (tilting) of deformed nuclei. This model was applied to analysis of the experimental angular anisotropy of fission fragments in the ¹⁶O + ²³²Th, ²³⁸U, ²⁴⁸Cm, ²⁰⁸Pb, ²⁰⁹Bi; ¹²C + ²³⁶U; ¹⁹F + ²⁰⁸Pb; and ¹¹B + ²³⁷Np reactions. Information on the equilibrating time of the tilting mode was obtained. The text was submitted by the authors in English.