Synthesis and reactivity of 10-Alkylphenotellurazines

The reaction of N-alkyl-2,2-dilithium diphenylamines with tellurium diiodide yields derivatives of a new heterocyclic system, phenotellurazine. 10-Alkyl-phenotellurazines readily form derivatives containing tetra- and tricoordinated tellurium, form complexes with metal salts and rhodium(I) carbonyl chloride, and by bromination and nitration give 3,7-dibromo- or 3-nitro-, 3,7-dinitro, and 1,3, 7,9-tetranitro derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 757–768, June, 1985.     

A study of nitrogen-containing bisheterocyclic systems

The dipole moments of N- and C-aryl and N- and C-furyl derivatives of imidazole and benzimidazole have been determined. A comparison of the dipole moments of the aryl derivatives found experimentally and calculated vectorially has shown they have a nonplanar structure. Conversely, derivatives of 2-(-furyl)-4,5-diphenylimidazole contain a planar bicyclic fragment. The hypothesis is put forward that the conformation of the bicyclic compounds studied is determined by a combination of steric and electronic factors.For Communication IV, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 6, pp. 819–823, June, 1970.     

Synthesis,crystal structure,and electroluminescent properties of zinc and cadmium tetradentate azomethine complexes

Chemical and electrochemical syntheses of zinc(II) and cadmium(II) complexes based on tetradentate Schiff bases (H₂L¹ and H₂L²) resulting from condensation of 2-tosylaminobenzaldehyde with 3,6-dioxa-1,8-octanediamine or 4,9-dioxa-1,12-dodecanediamine were performed. The structure, composition, and properties of the complexes were studied by elemental analysis, IR, ¹H NMR, and UV spectroscopy, X-ray absorption spectroscopy, and X-ray diffraction. The zinc(II) and cadmium(II) complexes luminesce in a DMF solution in the blue spectral region (λ_PL = 425–433 nm), the photoluminescence quantum yield φ being 0.25–0.30. Multilayer zinc(II)- and cadmium(II)-based electroluminescent structures with green-blue emission of the exciplex nature were fabricated.     

Metal chelates with salicylidene-3-carboethoxy-4,5-dimethylthiophene derivatives as azomethine ligands of a new type

New azomethine derivatives of salicylidene-3-carboethoxy-4,5-dimethylthiophene and their metal chelates are synthesized. The enolimine tautomeric form of the azomethine system of the ligand is determined from the data of ¹H NMR and IR spectroscopy. According to the IR spectral data, the structures of the Co, Ni, Cu, and Zn complexes are octahedral (the structure of the nickel complex is proved by X-ray diffraction analysis), whereas the palladium chelate has a square structure.     

Spectral Asymptotics for Higher-Order Ordinary Differential Equations

This paper gives one-term componentwise asymptotics for theM and spectral matrices of a self-adjoint realisation of aneven-order ordinary differential expression. The underlyinginterval is assumed to have at least one regular endpoint, andthe boundary conditions are supposed to be separated. Furthermore,the weight function and the reciprocal of the highest-ordercoefficient are supposed to be of regular variation at the regularendpoint, in the sense of Bingham, Goldie and Teugels. 1991Mathematics Subject Classification: 34B24, 34E05.