Decacyclene Radical Anions Showing Strong Low‐energy Intramolecular Absorption and Magnetic Coupling of Spins in a Hexagonal Network

Two salts of the aromatic hydrocarbon decacyclene, {cryptand[2.2.2](Cs⁺)} (decacyclene^.?) ( 1 ) and {Bu₃MeP⁺}(decacyclene^.?) ( 2 ), were obtained. In both salts, decacyclene^.? radical anions formed channels occupied by cations. However, corrugated hexagonal decacyclene^.? layers could be outlined in the crystal structure of 1 with several side‐by‐side C???C approaches. The decacyclene^.? radical anions showed strong distortion in both salts, deviating from the C₃ symmetry owing to the repulsion of closely arranged hydrogen atoms and the Jahn‐Teller effect. Radical anions showed intense unusually low energy absorption in the IR‐range, with maxima at 4800 and 6000 cm^?1. According to the carculations, these bands can originate from the SOMO‐LUMO+1 and SOMO‐LUMO+2 transitions, respectively. Radical anions exhibited a S=1/2 spin state, with an effective magnetic moment of 1.72 μ_B at 300 K. The decacyclene^.? spin antiferromagnetically coupled with a Weiss temperature of ?11 K. Spin ordering was not observed down to 1.9 K owing to spin frustration in the hexagonal decacyclene^.? layers.     

Study of structural aspects of thermochemical conversions of compounds modeling oligophenylenes containing acenaphthylenyl and acenaphthenyl groups

With the aim of elucidating the mechanism of the thermochemical conversion of oligophenylenes containing acenaphthylenyl groups, the thermolysis of model compounds: l,3,5-tris(5-acenaphthylenyl)benzene (1), 1,3,5-tris(5-acenaphthenyl)benzene (2), acenaphthylene, and acenaphthene, was studied by differential thermal analysis (DTA), dynamic thermogravimetric analysis (TGA), and mass spectrometry. Compounds1 and2 were studied by X-ray structural analysis. A scheme for the formation of secondary structures was suggested. Optimum temperature conditions were found for preparing thermostable, heat-resistant, and stable to thermooxidation polymers based on compounds containing the acenaphthylenyl groups.Deceased in 1993.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 846–854, May, 1994.We thank V. M. Laktionov for performing the differential scanning calorimetric analysis.