分子内電荷移動相互作用をもつ炭素陽イオン

抄録

This article deals with the recent development in the synthetic study of hydrocarbon systems composed of a stable carbocationic unit as an acceptor and a neutral π-electronic unit as a donor. Synthesis of such systems, which are defined as “undissociable charge-transfer (CT) complexes”, is important in clarifying the intramolecular π-electronic interaction in the corresponding neutral systems and correlating it with the molecular geometry. The reported carbocations are roughly classified according to the dihedral angle between the donor and acceptor units as follows : [n_m] cyclophane systems, 1, 8-disubstituted naphthalenes, janusene systems, 1, 2-disubstituted benzenes, and bicyclic systems related to triptycene or barrelene. The structural effects upon the observed intramolecular CT absorption, and upon the cation stabilization by through-space π-electron donation, are discussed together with the synthetic method for each of the cations. Some limited examples of the carbanions, which might have the intramolecular π-electronic interaction, are also surveyed.