Reduction of halogenated ketones with magnesium haloalkoxides

The degree of thermal stability of magnesium haloalkoxycarbinolates containing thienyl groups and dichloro-, trichloro-, and trifluoromethyl groups was explained. The effect of substituents in the thienyl group on the stability of the magnesium haloalkoxycarbinolates was studied.     

Response of timepix detector with GaAs:Cr and Si sensor to heavy ions

The response of the Timepix detector to neon ions with kinetic energy 77 and 158.4 MeV has been studied at the cyclotron U-400M of the JINR Flerov Laboratory of Nuclear Reaction. Sensors produced from gallium arsenide compensated by chromium and from silicon are used for these measurements. While in Timepix detector with Si sensor the well-known so-called “volcano effect” observed, in Timepix detector with GaAs:Cr sensor such effect was completely absent. In the work the behavior of the Timepix detector with GaAs:Cr sensor under irradiation with heavy ions is described in comparison with the detector based on Si sensor. Also the possible reason for absence of “volcano” effect in GaAs:Cr detector is proposed.     

Syntheses and reactions of some fluorinated dienes,cyclobutenes and furans

There are many reports¹ of the pyrolysis of fluorinated organic compounds, including the defluorination of cyclic fluorocarbons over iron to give aromatic compounds. Extending this technique we have investigated the flow pyrolysis of some readily accessible unsaturated fluorocarbons, such as I, II, and III, and found these to be synthetically

useful routes to fluorinated dienes, cyclobutenes, and furans. Pyrolyses were carried out using a nitrogen flow over platinum, iron or caesium fluoride heated at 430–700°. The various products can all be rationalized in terms of intermediate allylic radicals, and the solid substrate influences which allylic radicals are formed.We are also investigating the chemistry of those now accessible compounds, such as IV, V, and VI, and some of the preliminary results are described.

For example the fluoride ion induced dimerisation of IV gave two major products VII and VIII via a particular interesting mechanism.

     

Reactions of halogen metal alkoxides

The study of the thermal stability of halogen-magnesium alkoxy-carbinolates was continued. The data obtained led to the development of procedures for the synthesis of esters of α-oxo and of α-hydroxy-acids containing the thienyl radical. An intramolecular hydrogen bond between the sulfur atom and the hydrogen of the hydroxyl group in esters of (5-bromothienyl-2)glycolic acid was revealed. The presence of this bond was confirmed by infrared spectroscopic data and by the results of the investigation of the esters of (thienyl-3)- and (4-bromothienyl-3)glycolic acids.     

195Pt,15N NMR spectroscopy of aqueous solutions of mixed valent oxonitrocomplexes,Pt(II,IV): K5[(NO2)3PtIV(μ-O)3 Pt 3 II (NO2)6] and K8[(NO2)6Pt 3 II (μ-O)3PtIV(μ-O)3Pt 3 II (NO2)6]

Two aqueous solutions of oxonitrocomplexes comprising di- and tetravalent platinum atoms, K₅[(NO₂)₃Pt^IV(μ-O)₃Pt ₃ ^II (NO₂)₆]· 3H₂O and K₈[(NO₂)₆Pt ₃ ^II (μ-O)₃Pt^IV (μ-O)₃Pt ₃ ^II (NO₂)₆] · 7H₂O, have been studied by¹⁹⁵Pt and¹⁵N NMR technique. Both compounds, enriched with the¹⁵N (95%) isotope, were synthesized by thermal denitrozylation of K₂[Pt(NO₂)₄]. Constants of spin-spin scalar coupling,¹⁹⁵Pt-¹⁵N and¹⁹⁵Pt^II-¹⁹⁵Pt^IV, were obtained for tetra-and heptameric complexes in aqueous solutions through multiplet simulation. The¹⁹⁵Pt and¹⁵N NMR spectra of the same solutions obtained two months after their preparation show signals from the hydrolytic forms of the tetrameric complex as well as the signals from mono- di- and trimeric oxonitrocomplex forms of divalent platinum. All signals of species formed as a result of hydrolysis were identified.