Effect of the Central Atom of a Metal on the Structure and Frequencies of the Normal Vibrations of the Porphin Ligand

The structure and frequencies of the normal vibrations of the molecules of porphin, Mg-, Zh-, and Ni-porphin were calculated by the density-functional method in the B3LYP/6-31G(d) approximation, and correlation of their frequencies was made. The force fields have been obtained in dependent natural coordinates. It is shown that the majority of changes in the vibrational frequencies in transition from porphin to its metal complexes correlate with changes in the structure of the pyrrole and pyrrolenine rings of the porphin ligand.     

SYNTHESE DE NOUVEAUX DERIVES ORGANOPHOSPHORES BICYCLIQUES FONCTIONNELS

Abstract

Cycloaddition of dichlorophenylphosphine with 3,4-bis(methylene)-thiolane affords a bicyclic phospholenium salt; further reactions with water and dihydrogen sulfide give new series of bicyclic phospholenes.     

Investigation of Thyme (Thymus vulgaris L.) Essential Oil by Use of the BioArena System

JPC – Journal of Planar Chromatography – Modern TLC - The composition of the essential oil of Thymus vulgaris L. has been determined by GC-FID and GC-MS. Because separation of thymol,...     

Sum of Euler–Kronecker constants over consecutive cyclotomic fields

We give an asymptotic expansion of the sum of Euler–Kronecker constants related to cyclotomic fields with consecutive parameter.     

Measurement of the rate of nuclear capture of negative muons in the isotopes 84Kr and 136Xe

The lifetime of a negative muon in the 1S state in the isotopes ⁸⁴Kr and ¹³⁶Xe was measured. The values obtained, τ(⁸⁴Kr)=139.2±2.9 ns and τ(¹³⁶Xe)=111.0±4.6 ns, correspond to total nuclear capture rates Λ_c(⁸⁴Kr)=6.75±0.15 μs⁻¹ and Λ _c(¹³⁶Xe)=8.6±0.4 μs⁻¹. Theoretical calculations of the rate of nuclear capture of a negative muon are performed for the Kr isotopes. The experimental results are compared with the theoretical calculations. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 5, 302–307 (10 March 1998)     

Drainage in ground water flow over a screen

The paper deals with construction and investigation of a mathematical model for ground water flow from the earth's surface over a vertical impermeable screen with flow interception by a drain located on the screen surface.     

Stable radicals — The intermediates in the photochemical chlorination of unsaturated perfluoro compounds

We have studied the photochemical chlorination of perfluorinated alkenes, 1,2- and 1,3-dienes, and a cross-conjugated triene. By means of EPR we have recorded the stable intermediates, viz., alkyl and allyl radicals that can split off a chlorine atom. In every case formation of the allyl radical is regiospecific; the sterically least-strained structure is obtained.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1223–1227, May, 1991.