Synthesis and Crystal Structures of Bis(tetraethylammonium)(2-oxo-1,3-dithiole-4,5-dithiolato)zincate(II) and Bis(tetra-n-butylammonium)(2-oxo-1,3-dithiole-4,5-dithiolato)zincate(II)

The title compounds were prepared from 1,3,4,6-tetrathiapentalene-2,5-dione ( 1 ) in one step via the in situ generated intermediate 2-oxo-1,3-dithiole-4,5-dithiolate (dmid; 2 ). The X-ray single crystal structure of (Et₄N)₂[Zn(dmid)₂] ( 3 a ) gave the tetragonal space group P4₃2₁2 with a = b = 13.810(2) Å, c = 16.480(3) Å, and Z = 4. (n-Bu₄N)₂[Zn(dmid)₂] ( 3 b ) gave the triclinic space group P 1 with a = 11.947(4) Å, b = 14.665(5) Å, c = 16.662(8) Å, α = 100.21(3)°, β = 104.46(3)°, γ = 110.73(3)°, and Z = 2.     

Electrochemical interconversion of 1-(p-tolyl)-6-methyl-2,4-diphenylpyrimidinium perchlorate and 1-(p-tolyl)-6-methylene-2,4-diphenylpyrimidine

It is shown that reduction of the 6-methyl-1-(p-tolyl)-2,4-diphenylpyrimidinium cation proceeds in two one-electron stages. In the first stage, an unstable radical is formed, and in the second stage, an unstable anion. As a result of dehydrogenation of the radical, the anhydro base 6-methylene-1-p-tolyl-2,4-diphenyl-6H-pyrimidine is formed. Oxidation of this compound in a single one-electron stage forms an unstable cation radical, the hydrogenation of which leads to the original pyrimidinium cation. Data obtained by cyclic voltametry and electrosynthesis with subsequent identification of the products have shown that, the same as in the reaction with the hydroxide anion, the methyl-substituted pyrimidinium cation acts as a CH-acid.Rostov State University, Rostov-on-Don 344101, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 71–75, January, 1999.     

Spectral and luminescence properties and photochemical transformations of 7,7,9-trimethyl-6,7-dihydrofuro[3,2-<Emphasis Type="Italic">f</Emphasis>]quinoline

Spectral, luminescent, and photochemical properties of 7,7,9-trimethyl-6,7-dihydrofuro[3,2-f]quinoline (FDHQ) have been studied in hexane, alcohols, and water. Unlike 1,2-dihydroquinolines without the furo substituent, the fluorescence quantum yields for FDHQ in water and methanol are high (0.4 and 0.2, respectively), thereby indicating a difference in routes of excitation energy degradation in these compounds. The regularities in the FDHQ phototransformations have been studied by steady-state photolysis. The composition and the yield of final products depend on the presence or absence of oxygen in the system to a higher extent than on the solvent nature. This indicates the participation of the triplet excited state in the photo-chemical reactions in oxygen-free systems.     

Silicon-containing polyimides: synthesis,properties, and application as optical fiber light guide coatings

Russian Chemical Bulletin - Organosoluble polyimides with tetramethyldisiloxane fragments in the main chain were synthesized by one-step high-temperature polycondensation and their properties were...