Bis-para-semiquinoid type double cyclopalladation in the series of six-membered two-nitrogen bridged annulene-dihydroannulene ligands

The cyclometallation reaction known in the series of annulene heteroorganic ligands was extended to six-membered dihydroannulenes with a dinitrogen bridge. Double cyclopalladation of 4-methyl-4-trichloromethylcyclohexa-2,5-dien-1-one azine yielded the first representative of a new class of cross-conjugated diazadipalladatetracycles,viz., 5,10-bis(acetylacetonato)-2,7-dimethyl-2,7-bis(trichloromethyl)-2,7-dihydro-4b,9b-diaza-5,10-dipalladaindeno[2,1-a]indene, isolated as a diastereomer mixture of the achiralmeso-form (E-isomer) and a racemate (Z-isomer). This reaction offers a method for transition metal-mediated activation of non-reactive C−H bonds at position 2 of cyclohexa-2,5-dienylidene systems and a route toward the very rare chiral polyheteroelement system with rotational symmetry. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1236–1239, June, 1997.     

Perfluoroethanesulfonyl fluoride: Preparation from sultone

A procedure was developed for preparing perfluoroethanesulfonyl fluoride by synthesis of hexafluoropropane-2-β-sultone from sulfuric anhydride and perfluoropropene, followed by hydrolysis of the sultone to α-tetrafluoroethanesulfonyl fluoride and fluorination of the latter with elemental fluorine.     

Sulfur dioxide electrocatalysis of radical-chain trifluoromethylation of thiophenols by bromotrifluoromethane

The possibility of electrocatalysis by sulfur dioxide has been demonstrated in the trifluoromethylation of thiophenols by Freon F13B1 (CF₃Br) to form trifluoromethyl aryl sulfides. A study has been made of the influence of the mediator concentration, the electronic structure of the thiophenol, and the electrolysis conditions on the course of the trifluoromethylation process.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 29, No. 3, pp. 244–249, May–June, 1993.The authors wish to express their appreciation to the State Committee of the Ukraine on Matters of Science and Technology, for financial support of this work within the scope of the Fundamental Research Fund.     

Effect of thermal and chemical treatment on the structure and composition of nanodiamonds

The effect of chemical and thermal treatment on structural characteristics and chemical composition of detonation synthesis ultradispersed diamonds (UDDs) was studied. UDDs of five different producers were compared. Special attention was paid to structural characteristics of samples (size of coherent scattering regions, aggregation), which were determined by SEM, AFM, and X-ray diffraction methods. Impurities were analyzed by methods of mass spectrometry, atomic and absorption analysis, and X-ray spectral analysis.     

Quasi-elastic scattering of neutrons by a water dispersion of nanodiamonds

Data on quasi-elastic neutron scattering by a water dispersion of nanodiamonds and a pure water as a supporting system has been analyzed. The observed difference in the quasi-elastic neutron scattering spectra is interpreted using two different approaches developed to date for describing the behavior of a solvent in the cases of low and moderate concentrations of carbon nanoparticles (for example, fullerenes, nanotubes, ultradispersed diamonds). Within the first approach, it is assumed that the influence of dissolved nanoparticles leads to an insignificant change in the properties of the solvent. Within the second approach, the properties of the solvent are assumed to be invariable as compared to those of the pure liquid, except for a narrow boundary region of the order of two to three atomic layers near the surface of nanoparticles, where the properties of the solvent change drastically. The explanation of the effect within the second approach seems to be more reliable despite the apparent complication of the mathematical treatment of the experiment.