Metal complexes of 2-hetarylindandiones-1,3

The chelate and molecular complexes of 2-(2-benzazolyl, perimidyl)-indandiones-1,3 were synthesized for the first time. The structures of the ligands (tautomeric forms) and complex compounds were determined from the X-ray diffraction, ¹H, ¹³C NMR, and IR data and the quantum-chemical calculations (RHF SCF in 6-31 G** basis).     

Synthesis and crystal structure of divaleratobis(nicotinamide)copper(II)

A copper(II) valerate complex with nicotinamide (L) [CuL₂(C₄H₉COO)₂] (I) has been synthesized and studied by IR spectroscopy and thermogravimetry. The crystal structure has been determined. The crystals of 1 are monoclinic, a = 11.297(1) Å, b = 6.666(1) Å, c = 16.873(2) Å, b = 108.50(1)°, V = 1204.9(3) ų, Z = 2, space group P2₁/c. The structural units of the crystal of I are centrosymmetric tetragonal bipyramidal (4+2) complex molecules. The equatorial positions of the bipyramid are occupied by trans-arranged pairs of O (Cu-O, 1.973 Å) and N (Cu-N, 2.006 Å) atoms, and the axial positions are occupied by the second O atoms of the valerate anions located at longer distances (Cu-O, 2.506 Å). The supramolecular associates formed in the crystal are layers of hydrogen-bonded complexes. The disordered hydrocarbon “tails” of the valerate groups point toward the interlayer space.     

Correlation between stereochemistry and sign of cotton effects for degenerate transitions in spectra of binuclear clusters of molybdenum(II)

A correlation between the stereochemistry and sign of the Cotton effect for ^* transition in the spectra of dimolybdenum tetracarboxylates and related compounds has been accomplished by constructing, within the framework of a one-electron model of optical activity, a 32-sector rule based on data from x-ray structure analysis and circular dichroism for dimolybdenum tetra-(R)-mandelate. It has been shown that a positive value of the pseudoscalar function xyz(x²–y²)(a²-z²) corresponds to a negative Cotton effect for the ^* transition in the case in which the dominant contribution to this effect comes from R_x components of the rotator strength of the transition.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1783–1785, August, 1990.     

Effect of Extensin - Like Cotton Proteins on Eukaryotic Cell Gene

The effect of extensin-like cotton proteins (ELP) on animal cell gene (KML cell culture) was studied. Cells perish (50%) at protein dose 100 g/mL (cytotoxic effect). DNA fragmentation is not observed. Cell death from ELP is hypothesized to occur via necrosis resulting from destruction of intracellular biochemical processes     

Neutron studies of crystal-field effects in PrB<Subscript>6</Subscript>

The roles of various physical mechanisms in the properties of the ground state of the Pr ion in PrB₆ are studied by measuring magnetic excitation spectra in the paramagnetic and magnetically ordered phases of polycrystalline PrB₆. The ground state of the Pr ion in the paramagnetic phase is experimentally found to be triplet Γ₅. During the transition into the magnetically ordered state, this triplet splits into three singlet levels. The results obtained do not exclude the appearance of an additional contribution to the splitting induced by a decrease in the local symmetry because of structural distortions.     

Method for quantitative determination of allapinine in Aconitum leucostomum

Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 436–438, May–June, 1989.     

A Model System for the Study of Competitive Coordination in Aminoheterocyclic Complexes. Molecular and Crystal Structure of 2-Amino-1-methyl-Benzoimidazolium Chloride Hydrate

2-Amino-1-methyl-benzoimidazolium chloride hydrate was structurally characterized by X-ray diffraction analysis. Its crystal is built from organic cations, chloride anions, and molecules of crystallization water, which are united through a related system of hydrogen bonds. In the organic cation, the proton is localized at the N atom of the pyridine type.     

Influence of unstable valence of cerium ions on the crystal field in ReNi compounds

To examine the effect of hybridization of 4f electrons with conduction electrons on the crystal field potential using neutron spectroscopy, we studied the effects of the crystal electric field (CEF) in intermetallic compounds of the type ReNi, in which chemical substitution is followed by a transition of the cerium ions from an intermediate valence state to the Kondo state. Measurements were performed both on cerium ions in the compounds Ce_1−x La_xNi (x=0.5, 0.8), where they have a whole-number population of the 4f shell, and on the paramagnetic impurity ion Nd in the series of compounds Re_1−x Nd_xNi (Re=Ce, La, Y), in which the cerium ions are found either in an intermediate valence state or in the Kondo state. From the neutron inelastic magnetic scattering spectra on Nd ions, we have reconstructed the crystal field parameters in ReNi compounds and calculated the CEF level diagram of Ce ions in these compounds as functions of the interion distances Re-Ni. The results of our calculations are in good agreement with the experimentally determined splitting diagram of the ground-state multiplet of the Ce ions. We have determined that as the degree of hybridization with the conduction electrons grows the CEF potential varies considerably and the effective splitting of the 4f shell of the cerium ions increases. The estimated energy scale of the splitting of the ground-state multiplet of the Ce³⁺ ions in the ReNi CEF (Δ_CEF∼15 meV) turns out to be commensurate with the Kondo temperature (T _K ;140 K for CeNi. Analysis indicates that the CEF potential has a substantial effect on the formation of the valence-unstable ground state of the f shell in this compound. Zh. éksp. Teor. Fiz. 113, 1731–1747 (May 1998)