Anion effect on the thermolysis of double complexes [Co(NH3)6][Fe(CN)6] and [Co(NH3)6]4[Fe(CN)6]3

The thermolysis of complexes [Co(NH₃)₆][Fe(CN)₆] and [Co(NH_{3 6}]₄[Fe(CN)₆]₃ under an air or hydrogen atmosphere at 200, 350, and 500°C is studied. The composition and properties of thermolysis products are determined. The oxidative thermolysis yields mixtures of oxides of the central metals; the reductive thermolysis yields intermetallic compounds CoFe. The density of the complexes and the specific surface area of the intermetallic compounds are measured. Average particle sizes are calculated. The morphology and dispersion of the powders are dictated by the shape and density of the crystals of the precursor double salts and the thermolysis temperature. The thermolysis chemism in the oxidative and reductive atmospheres is discussed in the context of the nature of the complex anion. Original Russian Text ? S.I. Pechenyuk, D.P. Domonov, D.L. Rogachev, A.T. Belyavskii, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 7, pp. 1110–1115.     

Mono-reduced Corannulene: To Couple and Not to Couple in One Crystal

One-electron reduction of corannulene, C₂₀H₁₀, with Li metal in diglyme resulted in crystallization of [{Li⁺(diglyme)₂}₄(C₂₀H₁₀^.−)₂(C₂₀H₁₀-C₂₀H₁₀)²⁻] ( 1 ), as revealed by single-crystal X-ray diffraction. This hybrid product contains two corannulene monoanion-radicals along with a dianionic dimer, crystallized with four Li⁺ ions wrapped by diglyme molecules. The dimeric (C₂₀H₁₀-C₂₀H₁₀)²⁻ anion provides the first crystallographically confirmed example of spontaneous radical dimerization for C₂₀H₁₀^.−. The C−C bond length between the two C₂₀H₁₀^.− bowls of 1.588(5) Å is consistent with the single σ-bond character of the linker. The trans-disposition of two bowls in the centrosymmetric (C₂₀H₁₀-C₂₀H₁₀)²⁻ dimer is observed with the torsion angle around the central C−C bond of 180°. Comprehensive theoretical analysis of formation/decomposition processes of the dimeric dianion has been carried out in order to evaluate the nature of bonding and energetics of the C₂₀H₁₀^.− coupling. It is found that such σ-bonded dimers are thermodynamically unstable due to large preparation energy and repulsive Pauli component of the bonding, but kinetically persistent due to a high energy barrier provided by the existing spin-crossing point.     

Observation of an α-cluster structure in 36Ar

Excitation functions for ³²S+α elastic scattering are measured by a new method based on inverse kinematics and a thick gas target. Data corresponding to the ³⁶Ar excitation range 12–16 MeV are treated within the R-matrix approach. Spin-parity assignments are given for over 40 new levels.     

Astrophysical reaction rate for the neutron-generator reaction 13C(alpha,n)16O in asymptotic giant branch stars

The reaction 13C(alpha,n) is considered to be the main source of neutrons for the s process in asymptotic giant branch stars. At low energies, the cross section is dominated by the 1/2+ 6.356 MeV subthreshold resonance in (17)O whose contribution at stellar temperatures is uncertain by a factor of 10. In this work, we performed the most precise determination of the low-energy astrophysical S factor using the indirect asymptotic normalization (ANC) technique. The alpha-particle ANC for the subthreshold state has been measured using the sub-Coulomb alpha-transfer reaction ((6)Li,d). Using the determined ANC, we calculated S(0), which turns out to be an order of magnitude smaller than in the nuclear astrophysics compilation of reaction rates.     

Structure of K3ZrF5SO4·H2O

Institute of the Chemistry and Technology of Rare Elements and Mineral Rare Materials, Academy of Sciences of the USSR, Kazakh Scientific Center. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 4, pp. 182–184, July–August, 1989.     

Antimicrobial Activity of Composite Hydrogels in the Poly(N-vinylpyrrolidone)–RE(NO3)3 · xH2O (RE Are Rare-Earth Ions) System

Crystallography Reports - The bactericidal and bacteriostatic properties (in darkness) of salts RE(NO3)3 · xH2O (RE = La, Ce, Gd, Yb, Y) and composite hydrogels with poly(N-vinylpyrrolidone)...     

Study of the proton-rich nucleus 8B in the resonance scattering of radioactive 7Be by hydrogen

The excitation function is measured for ⁷Be+p elastic resonance scattering at an angle of 180° in the center-of-mass frame. The measurements are made by a new method which combines the advantages of inverse kinematics and thick targets. New information is obtained about the structure of the levels in the ⁸B nucleus. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 12, 959–963 (25 June 1998)