Radikaltrianionen von Isopyrenen

Radical Trianions of Isopyrenes The radical trianions derived from acepleiadylene (1) , dicyclopenta [ ef , kl ]heptalene (2) and dicyclohepta [ cd , gh ]‐pentalene (3) are described. Whereas the hyperfine data of \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{3\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ 2^{3\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} are consistent with the predictions of an HMO‐ McLachlan ‐procedure, the corresponding data of \documentclass{article}\pagestyle{empty}\begin{document}$ 3^{3\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} substantially differ from the calculated values. The spin distribution in \documentclass{article}\pagestyle{empty}\begin{document}$ 3^{3\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} is polarized by the counterions in such a way, that the hyperfine data of this radical trianion no longer reflect the D 2 h ‐symmetry of the neutral compound 3 and the radical anion \documentclass{article}\pagestyle{empty}\begin{document}$ 3^{\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} . In addition, the interaction of the charged organic ion \documentclass{article}\pagestyle{empty}\begin{document}$ 3^{3\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} with the counterions influences the energy of the low‐lying antibonding molecular orbitals LUMO (lowest unoccupied molecular orbital) and NLUMO (next lowest unoccupied molecular orbital). The passage from a looser ion pair ( \documentclass{article}\pagestyle{empty}\begin{document}$ 3^{3\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} /3Li + ) to a tighter ion pair ( \documentclass{article}\pagestyle{empty}\begin{document}$ 3^{3\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} /3Na + , \documentclass{article}\pagestyle{empty}\begin{document}$ 3^{3\scriptstyle {{\relbar}\kern-4pt {.} }} $\end{document} /3K + ) causes a change in the orbital sequence of LUMO and NLUMO.