DFT study on a fullerene doped with Si and N

DFT calculations are applied for some stable C₆₀, C₅₉Si, and C₅₉N hetero fullerenes. Sn and Ge atoms are doped at the same position of C₆₀. Computations are carried out at the B3LYP/cc pVDZ levels. In this work the effects of the heteroatoms, Si and N, on the structural properties of the fullerene have been studied. The structure, energetic and relative stabilities of the compounds were compared and analyzed with each other. In addition, vibrations spectra of proposed stable neutral species, as well as the infrared intensities are calculated. From the data obtained from calculation, we found that there is strong correlation between the stability of pure C₆₀ fullerene molecule and the numbers of different C-C bonds.     

Long-range relativistic heavy atom effect on 1H NMR chemical shifts of selenium- and tellurium-containing compounds

Previously unknown manifestation of heavy atom effect on the NMR chemical shifts of β- and γ-protons initiated by the relativistic effects of the tellurium and selenium atoms has been investigated in the representative series of selenium- and tellurium-containing compounds. To approve the four-component density functional approach to be the appropriate tool for the investigation of the heavy atom on light atom effect (HALA), the benchmark calculations of the proton chemical shifts have been performed at the CCSD level using comprehensively chosen locally dense basis set with taking into account solvent, vibrational, and relativistic corrections. A good agreement with the experimental data was achieved. The magnitudes of the relativistic HALA corrections to β- and γ-proton chemical shifts were found to vary in a wide range, namely from −3.08 ppm for the γ-proton of methyltelluraldehyde to 14.51 ppm for β-proton in benzotelluraldehyde.     

Tetrathiaoxa Macrocycles with Dibenzo-subunits: A Search for New Tl(I)- and Ag(I)-Selective Ionophores

Novel S⁴O ⁿ mixed donor macrocycles (1, n=1; 2, n=2) were synthesized by the coupling reactions of corresponding dichlorides with dithiols under high dilution conditions. Synthesis and crystal structures of Tl⁺ and Ag⁺ complexes, [Tl(2)⁺ and Ag(2)⁺], with macrocycle 2 are described. The electrode based on macrocycle 2 showed excellent potentiometric sensing ability for Tl⁺ and Ag⁺ ions. This remarkable sensing of the proposed electrode can be understood in terms of the synergy effect of a soft–soft acid–base interaction and π-coordination, especially for the Tl⁺ ion, which was observed from the crystal structure of the corresponding complex.     

Fluorine spin–spin coupling constants of pentafluorobenzene revisited at the ab initio correlated levels

All possible spin–spin coupling constants, ¹⁹F–¹⁹F, ¹⁹F–¹³C, and ¹⁹F–¹H, of pentafluorobenzene were calculated at five different levels of theory, HF, DFT, SOPPA (CCSD), CCSD, and the SOPPA (CCSD)-based composite scheme with taking into account solvent, vibrational, relativistic, and correlation corrections. Most corrections were next to negligible for the long-range couplings but quite essential for the one-bond carbon–fluorine coupling constants. Hartree–Fock calculations were found to be entirely unreliable, while DFT results were comparable in accuracy with the data obtained using the wave function-based methods.     

Magnetic Ordering of Strongly Magnetized Massive Nd<Subscript>2</Subscript>Fe<Subscript>14</Subscript>B Magnets

The magnetic ordering of a strongly magnetized massive rectangular magnet is studied via magnetic force microscopy. The magnetic ordering structures on the magnet’s surface are determined. An attempt is made to interpret the observed magnetic ordering by analyzing the simplest magnetic ordering models theoretically.     

A study of coherent dissociation of C → 3α in usual and enriched by Pb emulsions

A search for the coherent dissociation ¹²C → 3α in emulsion enriched by Pb and the comparative analysis of our data with ones obtained in usual emulsions have been made at 4.5 A GeV/c. Both of experiments cannot be described in the framework of statistical model of the ¹²C → 3α decay.     

On uniqueness of solution of a reverse problem of magnetic location

An analysis of solution uniqueness for a problem of magnetic dipole localization based on known values of magnetic field strength vectors at two points is presented. It is shown that a usage of two triples (pairs) of sensors is sufficient to solve a 3D (2D) problem of arbitrary magnetic dipole localization with a satisfactory number of crude errors.     

Peripheral fragmentation of relativistic nuclei 11B in nuclear track emulsion

Data obtained from a nuclear track photoemulsion exposed to a beam of ¹¹B nuclei with a momentum of 2.75 GeV/c per nucleon are reported. Peripheral interactions where the total charge of particles emitted within the forward cone of relativistic fragmentation is equal to the charge of the projectile nucleus are analyzed to study the clustering of the ¹¹T nucleus. It is found that the three-body breakup of 2 + 2 + 1 charge configuration is a leading process. Tritons are revealed to play a crucial role in the most peripheral interactions of this type. Events interpreted as charge exchange of the 11B nucleus to excited states of the ¹¹C* nucleus above the nucleon-coupling threshold were observed for the first time. Prospects for studying the ¹¹C nucleus are discussed.