Synthesis of 2-alkylthio-5-acetyl-2-oxazolines

The reaction of 2-acetyloxiranes with alkyl thiocyanates in the presence of Lewis acids (BF₃, AlCl₃) has given 2-alkylthio-5-acetyl-2-oxazolines (yields 40–60%). It has been shown that the reaction of trans-2-acetyl-3-methyloxirane and of trans-2-acetyl-3-methyloxirane and of trans-2-acetyl-2,3-dimethyloxirane with alkyl thiocyanates takes place stereospecifically and leads to cis-2-alkylthio-5-acetyl-2-oxazolines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 468–471, April, 1980.     

Growth and morphological study of copper oxide single crystals

Experiments on the growth of CuO single crystals by crystallization from flux in the CuO-Bi₂O₃-PbO-PbF₂, CuO-Bi₂O₃-Li₂O, CuO-Bi₂O₃-B₂O₃, CuO-BaO-Y₂O₃, and CuO-MO_x systems (M = P, V, or Mo) have been performed. The best results were obtained in crystallization in the CuO-Bi₂O₃-PbF₂ system: prismatic single crystals of platelet-and needlelike or isometric habit with dimensions up to 1 × 10 × 10, 1 × 1 × 20, or 6 × 6 × 8 mm, respectively, have been grown. The CuO crystals show polysynthetic twinning in the form of numerous alternating light and dark bands bound by systems of parallel straight lines on the {110} and {111} faces. A possible model of twinning associated with the Cu₂O → CuO transformation is considered.     

Structural Investigations of RNA–Protein Complexes in Post-Ribosomal Era

Crystallography Reports - Structural studies of RNA–protein complexes are important for understanding many molecular mechanisms occurring in cells (e.g., regulation of protein synthesis and...     

Synthesis of 5-substituted tetrazoles based on the disodium salt of azotetrazole. investigation of the azotetrazole-2-(tetrazolyl-5)-6-imino-1,2,3,4-pentazine mesoion tautomerism

For the example of a salt of azotetrazole, for the first time we have investigated the azotetrazole-1,2,3,4,5-pentazine tautomerism. Upon treatment of an excess of the disodium salt of azotetrazole with dilute sulfuric acid, we isolated 5-substituted tetrazole, which on the basis of analysis data (with introduction of the ¹⁵N isotope into the compound) and study of the chemical properties with sufficiently high probability of assigning the structure of the first representative of the previously unknown class of compounds of the pentazine mesoion: the tetrahydrate of the sodium salt of the 2-(tetrazolyl-5)-6-imino-1,2,3,4,5-pentazine mesoion. We synthesized the dehydrate of the sodium and silver salts of 5-azodiazomethanotetrazole; using derivatography, we have studied the properties of the isolated compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 468–475, April, 1993.     

Theoretical study on the group 2 atoms + N2O reactions

The electronic structure aspects of the M (1S,3P) + N2O(X 1sigma+) (M = Be, Mg, Ca) reactions are investigated using the CASSCF/MRMP2 (complete active space SCF and the multireference M?ller-Plesset perturbation theory of the second order) computational methodology. The lowest adiabatic 1 1A' and 1 3A' potential energy surfaces (PESs) favor the bending dissociation mechanism of N2O in all studied cases. The rate-limiting channels are determined by the classical barriers that decrease in the series Be (8.9) > Mg (7.0) > Ca (1.2) kcal/mol, whereas the spin-forbidden reaction channels are found to be less important. A comparison with elaborated kinetic results (Plane et al. J. Phys. Chem. 1990, 94, 5255; Gas-Phase Metal Reactions; Elsevier: Amsterdam, 1992; Vinckier et al. J. Phys. Chem. A 1999, 103, 5328) on the Ca (1S) + N2O(X 1sigma+) reaction is presented, and the differences in the kinetic behavior of the title reactions are discussed. Our results also indicate that the techniques based on the multiconfigurational wave functions are unavoidable if a correct topology of the PESs governing these reactions is needed.