Synthesis of benzo-ortho-thiazines S-oxides by Diels-Alder reaction of N-sulfinylanilines with norbornadiene

From substituted N-sulfinylanilines acting as dienes in the Diels-Alder reaction with norbornadiene S-oxides of benzo-ortho-thiazines were obtained, which were oxidized into the corresponding S,S-dioxides belonging to the class of hybrid thiazinesulfonamide compounds.     

Optical activity and crystalline structure of crystals of the langasite family

The dependences of the refraction on the structural parameters are considered for the La₃Ga_5.5Nb_0.5O₁₄, La₃Ga_5.5Ta_0.5O₁₄, La₃Ga₅SiO₁₄, Ca₃Ga₂Ge₄O₁₄, and Sr₃Ga₂Ge₄O₁₄ crystals of the langasite family. It is shown that the angle of deviation of the 1a octahedron faces that are normal to the optical axis from 60° is one of the main sources of optical activity of these crystals. The interaction of the cations belonging to the 3e dodecahedron and 1a octahedron, cations of the 3e dodecahedron and 2d tetrahedron, and the repulsion of O²⁻ ions are believed to be the basic interactions affecting the angle value. The dependences of the angle on the crystal-chemical characteristics of the considered crystals are analyzed. The role of the relative sizes of the structural polyhedra is demonstrated.     

N-sulfinylanilines as dienes in the Diels-Alder reaction. Structural aspects

Reactions of N-sulfinylanilines with norbornene and norbornadiene result in the Diels-Alder adducts of benzo-ortho-thiazine structure, which was confirmed by the NMR, IR spectroscopy and XRD analysis. In all cases the diene added to the norbornenes bicyclic system at the side of the endo-methylene bridge. The methyl group of meta-N-sulfinyl toluidine directs the norbornene entry into the para-position.     

Spectroscopy studies of pure and chromium-doped calcium gallogermanate crystals, Ca3Ga2Ge4O14

Absorption spectra, the spectra of circular dichroism and magnetic circular dichroism of pure and Cr-doped Ca₃Ga₂Ge₄O₁₄ crystals have been studied. The crystal-field parameters and the transition frequencies of Cr³⁺ ions are calculated. The location of Cr³⁺ and Cr⁴⁺ ions in oxygen octahedra and tetrahedra is confirmed. The spectra of circular dichroism show the maxima due to Cr³⁺ ions and growth-induced defects.     

Crystal structure of cyclic sulfin- and sulfonamides of the thiazine series: Conformation,intra- and intermolecular interactions

An X-ray crystallographic study of a new compound is performed and the structure of five sulfin- and sulfonamides of the thiazine series is discussed. The conformation of the thiazine ring in all structures (a distorted boat) is stabilized by the intramolecular interaction of the C-H…N type. The nitrogen atom of the thiazine ring has a pyramidal configuration. The geometry of isolated molecules is calculated at density functional theory level (PBE1PBE, 6-31G(d,p)) and compared to that observed in the crystals. In the crystal structures different packing motifs are implemented with the formation of supramolecular associates of different types due to classical hydrogen bonds such as N-H…O.     

Acylated benzothiazinesulfoneamides: Synthesis and molecular structure

1,2,3,4,4a,10b-Hexahydro-1,4-methano-6H-dibenzo[c,e]-5,6-thiazine-5,5-dioxide has been converted into the corresponding N-acyl derivatives via the reaction with acid chlorides and anhydrides. X-Ray diffraction data have revealed the presence of an intramolecular С–H···O=S hydrogen bond in the molecules of the obtained compounds.     

Electrons of <Emphasis Type="Italic">l</Emphasis> shells of free atoms as a regular system of points on a sphere: I. Modeling by polyhedra

Electron l shells of free atoms have been modeled on the basis of regular and semiregular polyhedra by determining stable systems of identical Coulomb particles with an increase in their number. It is shown that such stable systems correspond to the location of the maxima of electron density at the vertices of inversion-center polyhedra forming a sequence in which the first polyhedron has two vertices and the number of vertices in each subsequent polyhedron exceeds the number of vertices in the previous one by four. The electron s, p, d, and f shells are modeled by a dumbbell and trigonal, pentagonal, and heptagonal antiprisms, respectively. Thus, in addition to the quantum-mechanical properties, l shells should have the symmetry properties of these antiprisms. It is believed that consideration of the noncrystallographic (for the three-dimensional Euclidean space) fivefold and seven-fold symmetries of d and f shells of free atoms will make it possible to obtain a unified explanation for a number of phenomena in crystal structures and other ordered media.