Conversion of 2-amino-5-R-phenyl-1,3,4-oxadiazoles into 3-R-phenyl-5-alkoxy-1,2,4-triazoles

2-Amino-5-R-phenyl-1,3,4-oxadiazoles have been shown to isomerize in alcoholic potassium hydroxide solution to 3-R-phenyl-5-alkoxy-1,2,4-triazoles. The dissociative ionization of 3-R-phenyl-5-alkoxy-1,2,4-triazoles and 3-R-phenyl-1,2,4-triazolin-5-ones has been examined. The mass spectra of the oxadiazoles have been compared with those of the triazoles.Translated from Khimiya Geterotslklicheskikh Soedinenii, No. 11, pp. 1553–1556, November, 1986.     

Polymethine dyes — Indolo[3,2-d]thiazole derivatives

New polymethine dyes with an indolo[3,2-d]thiazole residue are described, and their spectral properties are discussed. Replacement of the vinylene group in the naphtho[1,2-d]thiazole residue by an NH group leads to a considerably greater bathochromic shift of the absorption maximum of carbo- and merocyanines as compared with replacement by a sulfur atom. The basicity of the indolo[3,2-d]thiazole residue is higher than the basicity of the naphtho[1,2-d]-thiazole and thionaphtheno[3,2-d]thiazole residues.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1606–1610, December, 1972.     

Methyl-substituted heterocyclic bases containing condensed selenonaphthene rings

The synthesis of 2-methylselenonaphtheno[2,3-d]thiazole and 2-methylselenonaphtheno[2,3-d]-oxazole is described.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 37–38, January, 1971.     

Crystal and molecular structure of 5-ethyl-5,10-dihydrido-10,10-diphenylphenazasiline

The structure of 5-ethyl-5,10-dihydro-10,10-diphenylphenazasiline has been determined from three-dimensional X-ray data collected by counter methods. The compound in the monoclinic space group P2₁/b with a 10.782(5), b 22.642(9), c 8.830(4) Å and γ 74°41′(2). The observed and calculated densities (Z = 4) are 1.22 and 1.21 g cm^-3, respectively. Anisotropic(Si, N, C)-isotropic block-diagonal least squares refinement gave a conventional R factor of 3.9% for 1871 reflections with I>2σ(I). The central six-membered ring of the tricyclic system adopts a boat conformation; the dihedral angle between the benzo-group planes is 157.3°. The CSiC angle in the heterocycle is 101.1(1)°; the mean SiC bond length is 1.850(2) Å (in the cycle) and 1.862(2) Å (with Ph group). The nitrogen atom is displaced 0.05 Å from the plane of the adjacent carbon atoms; the sum of the angle about N is 359.7°.     

Angular dependence of inductive effect and cis—trans influence in coordination compounds

Within the framework of the perturbation theory the implication of excited antibonding states in chemical bonding through the replacement of the AX bond by a more covalent AL bond in octahedra AX^″±₆ is shown to bring about greater weakening of the AX_tr bond in compounds of transition elements and of the AX_cis bond in compounds of non-transition elements. Weakening of AX_i bonds is proportional to non-diagonal matrix elements a_cis and a_tr between the respective localized orbitals. On the basis of these calculations the angular dependence of the inductive effect is also determined for compounds with multiple and donor—acceptor bonds. The predominant direction of the inductive effect in mutual influence of ligands depends on the nature of the atom A. The role of nonvalent interactions for determining the relative strength of bonds is considered. Theoretical conclusions are in agreement with the experimental data.     

Die IR-Spektren der Phasen ABTe3O8 (A = Fe,In, Sc; B = Nb,Ta) und UTe3O9

I.R. Spectra of the Phases A B Te₃O₈ (A = Fe, In, Sc; B = Nb, Ta) and UTe₃O₉ The infrared spectra of the title compounds have been recorded and discussed in comparison to formerly investigated M^IVTe₃O₈ phases. The spectrum of UTe₃O₉ (synthetic cliffordite) confirms the presence of uranyl groups and the structural relation of this compound to the fluorite.     

Synthesis and some properties of the diphenylmethyl and triphenylmethyl esters of uridine-3'phosphate

Summary The diphenylmethyl and triphenylmethyl esters of uridine-3'phosphate have been obtained and their stability under various conditions has been studied.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 1, pp. 48–51, 1966     

Studies in the benzazole and naphthazole series. VIII. Reaction of 2-hydrazinonaphth[1, 2-d]imidazole and its 1- and 3-methyl derivatives with carbon disulfide

When heated with carbon disulfide in pyridine 2-hydrazinonaphth[1, 2-d]imidazole yields S-triazolo[4, 3-b]-naphth[1, 2-d]imidazole-3-thione. Kinetic and not steric factors determine the formation of this compound. Its trans-angular structure is demonstrated by the agreement between its UV spectrum and that of 11-methyl-S-triazolo[4, 3-b]naphth[1, 2-d]imidazole-3-thione, prepared from 1-methyl-2-hydrazinonaphth[1, 2-d]imidazole and carbon disulfide, as well as by the identity of their methylation products. Methyl iodide methylation, in the presence of sodium methoxide, of S-triazolo[4, 3-b]naphth[1, 2-d]imidazole-3-thione, like that of S-triazolo[4, 3-a]benzimidazole-3-thione, takes place stepwise. First the methyl group adds to the nitrogen atom of the imidazole ring, and only then to the thiol group of the triazole ring.For Part VII see [3].     

Semiempirical andab initio study of the structure of the alumophenylsiloxane complex and its fragments

The structures, spectra, and electron density distributions of the alumophenylsiloxane (APS) complex and its fragments have been calculated using semiempirical (AM1) and ab initio (SCF/3-21G and SCF/6-31G^*) quantum chemical approximations. It has been shown that the local properties of the central fragment of alumophenylsiloxane, which is a slightly distorted tetrahedron AlO₄, are described with the (LiO)₂AlOBe(OH) cluster. M. V. Lomonosov Moscow State University. I. M. Gubkin State Academy of Oil and Gas. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 3, pp. 410–417, May–June, 1995. Translated by I. Izvekova