Abnormal broadening in triplet-to-triplet absorption spectra caused by aromatic solvents

The triplet-triplet absorption spectra of a number of aromatic molecules were shown to be broadened in low temperature matrices formed by aromatic solvents (toluene, 4-isopropylbiphenyl) as compared with those in aliphatic solvents (ethanol, methylcyclohexane, triethylamine). The effect is exponentially dependent on the energy of the upper triplet state of the solute molecule. The phenomenon is discussed in terms of a strong exchange-resonance interaction between the triplet states of solute and solvent.     

Chemistry of esters of keto acids of the acetylene series. X. Addition of amines to 3-phenylethynyl-1-quinoxalone

The reaction of 3-phenylethynyl-2-quinoxalones with aliphatic and aromatic amines gives alkyl(aryl)imines of 3-phenacylidene-2-quinoxalone, the structures of which were proved by alternative synthesis from 3-phenacylidene-2-quinoxalone and the appropriate amines.See [1] for communication IX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 276–277, February, 1976.     

Synthesen von α,β-ungesättigten 2-(2-Oxo-benzazolin-3-yl)-3-hydroxy-dithio-carbonsäure-alkylestern und entsprechend substituierten Keten-S,S-acetalen sowie deren Kristall- und Molekülstruktur

Summary The new alkyl 2-(2-oxo-benzazoline-3-yl)-3-hydroxy dithiocrotonates and dithiocinnamates4 and the corresponding ketene dithioacetals2 and5 are obtained by dithiocarboxylation of the 3-acceptormethyl substituted benzazoline-2-ones1 or3. Alkylation at room temperature gives compounds4 whereas at higher alkylation temperature2 or5 are formed. The results of X-ray analyses performed for methyl 3-hydroxy-p-chloro-dithiocinnamate4d and of N-[1-(4-chloro-benzoyl)-2,2-bis(methylthio)-vinyl]-benzothiazoline-2-one5e are discussed.

     

Quantum chemical calculations of the molecular structure of diphenylguanidine and experimental studies of its tautomerism in solution

MNDO-PM3 and AM1 quantum chemical calculations of the molecular structure of N,N′-diphenyl-guanidine (DPG) prove that the molecule preferably exists as an asymmetric tautomer with a basic center C = N−. IR and UV spectral data, dipole moments, and average molecular weights of DPG solutions in nonpolar and low-polar solvents confirm the results of calculations, indicating formation of hydrogen-bonded cyclic self-associates of DPG in solution. Translated fromZhumal Strukturnoi Khimii, Vol. 39, No. 4, pp. 618–625, July–August, 1998.     

Substitutive sulfotrioxidation of unsaturated and araliphatic organofluorine compounds

Conclusions Reaction of SO₂ or SO₃/[B₂O₃] with terminal fluoroolefins or fluoroalkylbenzenes gives the corresponding fluoroalken-2-yl fluorosulfates and fluorobenzyl fluorosulfates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2791–2795, December, 1982.