Preparation of polyfluorinated cycloalk-1-enyl-, alk-1-enyl-, and alkyliodine tetrafluorides using XeF2 in the presence of appropriate Lewis acids as fluorooxidant

Previously unknown polyfluorocyclohexenyl, and acyclic perfluoroalkenyliodine tetrafluorides were prepared in high yields. Perfluorocyclohex-1-enyliodine tetrafluoride was obtained from pentafluoroiodobenzene using XeF₂-NbF₅ in aHF. The reaction of C₆F₅I with the weaker fluorooxidant XeF₂-BF₃ in 1,1,1,3,3-pentafluorobutane (PFB) yielded C₆F₅IF₂, perfluorocyclohexa-1,4-dienyliodine difluoride, C₆F₅IF₄, perfluorocyclohexa-1,4, and 1,3-dienyliodine tetrafluoride as intermediate products on parallel reaction routes. Both perfluoroalkenyl iodides, cis- and trans-(CF₃)₂CFCFCFI, reacted with XeF₂-BF₃ in PFB to give the corresponding perfluoroalkenyliodine tetrafluorides, cis- and trans-(CF₃)₂CFCFCFIF₄. Even perfluoroalkyl iodides can be fluorinated by this reagent as was demonstrated by the preparation of C₆F₁₃IF₄ from C₆F₁₃I. Generally, the CFCIF_n fragment (n = 0, 2, or 4) in cyclic or acyclic perfluoroalkenyliodine compounds R_FIF_n did not undergo a transformation to the corresponding perfluoroalkyliodine compound. Furthermore, no perfluoroorganoiodine hexafluorides were detected in reactions with the fluorooxidant XeF₂-aHF or BF₃ or NbF₅.     

C-I stretching vibrations in iodobenzenes

Comparison of the calculated and experimental IR and Raman spectra of a series of iodobenzenes showed that the C-I stretching vibrations for these compounds correspond to a very highly polarized Raman band at 150–270 cm^–1 (=0.1). The position of this band depends on the mass of the para substituent and relative position of the fluorine and iodine atoms in the molecule. The UV absorption spectral data indicate an interaction of the iodine atom and para substituents through the -system. Opposite substituent effects on the change in intensity of the B-band in the UV spectra of iodobenzenes and tetrafluoroiodobenzenes were noted.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2637–2639, November, 1991.     

Hydrogenating properties of complex rhenidm(VLI) oxides with perovskite structure

Conclusions Rhenium oxides with perovskite structure of the general formula where B^III=Y and Sm, and Ba₃LaZnReWO₁₂ containing Re(VII), exhibit catalytic activity in hydrogenation of ethyl acetate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1236–1238, June, 1986.     

On the lowest order electroweak corrections to spin-12 fermion scattering: (I). The one-loop diagrammar

Based on a gauge model of the electroweak interaction the total set of all one-loop diagrams for scattering of $\text{spin}\text{-}\text{1}\text{2}$ fermions is calculated. Throughout the calculations, the type of fermions (?, ν, …) and of heavy vector bosons (W^±Z⁰, …) is not specified. Derivation of finite parts of each diagram is carried out under the restriction that all invariants of the amplitude are much larger than all fermion masses squared. This allows us to use the expression obtained at arbitrary high energies where weak and electromagnetic interaction strengths are comparable.     

Atomic parity-violation and precision physics

The atomic parity-violation (APV) parameter for a nucleus with n neutrons and z protons has been included in the list of pseudo-observables accessible with the codes TOPAZ0 and ZFITTER. In this way one can add the APV results in the LEP EWWG “global” electroweak fits, checking the corresponding effect when added to the existing precision measurements. Received: 8 March 2001 / Published online: 21 September 2001     

Electroweak radiative corrections to single top production

Fortran subroutines to calculate helicity amplitudes with massive spin-3/2 particles, such as massive gravitinos, which couple to the standard model and supersymmetric particles via the supercurrent, are added to the HELAS (HELicity Amplitude Subroutines) library. They are coded in such a way that arbitrary amplitudes with external gravitinos can be generated automatically by MadGraph, after slight modifications. All the codes have been tested carefully by making use of the gauge invariance of the helicity amplitudes.     

Electroweak radiative corrections to the three channels of the process f<Subscript>1</Subscript>f̄<Subscript>1</Subscript>HA→0

In this paper we describe the implementation of the complete next-to-leading order electroweak calculations for the various cross channels of the process f₁f̄₁HA→0 in the framework of the SANC system. Here A stands for a photon and f₁ for a fermion whose mass is neglected everywhere besides arguments of logarithmic functions. The symbol →0 means that all 4-momenta of the external particles flow inwards. The derived one-loop scalar form factors can be used for any cross channel after an appropriate permutation of their arguments s,t,u. We present the complete analytical results for the covariant and helicity amplitudes for three cross channels: f₁f̄₁→Hγ, H→f₁f̄₁γ and f₁γ→f₁H. For checking of the correctness of the results first of all we observe the independence of the scalar form factors on the gauge parameters and the validity of the Ward identity (external photon transversality), and, secondly, we make an extensive comparison of our numerical results with other independent calculations. PACS 12.15.-y; 12.15.Lk     

The stability of the equilibrium of a pendulum for vertical oscillations of the point of suspension

The motion of a pendulum, the point of suspension of which is subject to vertical harmonic oscillations of arbitrary frequency and amplitude, is considered. A complete rigorous solution of the non-linear problem of the stability of the relative positions of equilibrium of the pendulum along the vertical is given.