- Investigation of Spin Density Transfer into Cyclopropyl and Cyclohexyl Groups by ENDOR and TRIPLE Resonance, INDO and MINDO/3 Calculations
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By performing EPR, ENDOR, and TRIPLE experiments on the 1-cyclopropyl- and 1-cyclohexylphenalenyl radicals as well as the radical anions of 9-cyclopropyl- and 9-cyclohexylanthracene the hyperfine coupling constants, including their signs, were determined.An attempt was made to determine the optimum geometries of these radicals or of model systems by MINDO/3 caclculations.The dependence of the potential functions as well as the hyperfine coupling constants of the radicals on the dihedral angle between the cycloalkyl group and the ?-system were calculated by the INDO method.Conclusions with respect to the preferred conformations and the mechanism of spin density transfer into the cycloalkyl groups were drawn from a comparison with the experimental data.The hindrance of free rotation of the cycloalkyl groups is mainly caused by steric interactions with hydrogen atoms in peri-positions.Whereas the two ring systems are oriented almost perpendicular to each other in the radical anion of 9-cyclohexylanthracene, the eclipsed conformation is preferred in the corresponding cyclopropyl compound.
- Kirste, Burkhard,Broser, Waldemar,Grain, Kornelia,Kurreck, Harry,Schloemp, Gerhard
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p. 3464 - 3480
(2007/10/02)
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- Photochemical reaction of anthracene in cyclohexane polycrystals dispersed in liquid nitrogen
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U.v. photolysis of a polycrystalline solution of anthracene in cyclohexane at 77 K followed by separation of the stable photoproducts at room temperature, yielded 9,10-dihydroanthracene, 9-cyclohexyl-9,10-dihydroanthracene, 9-cyclohexylanthracene, and oxidized derivatives of anthracene.
- Lamotte, Michel,Lapouyade, Rene,Pereyre, Josette,Joussot-Dubien, Jacques
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p. 725 - 726
(2007/10/02)
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