Isolation and X-ray structural characterization of a dicationic homotrimer of 2,3,6,7-tetramethoxy-9,10-dimethylanthracene cation radical

摘要

Electrochemical oxidation of 2,3.6,7-tetramethoxy-9,10-dimethylanthracene (1) showed that it undergoes a highly reversible electrochemical oxidation (E_(ox) = 0.81 V vs SCE) and forms a modestly stable cation-radical salt in solution. X-ray crystallography established that 1~+- SbCl_6~- crystallizes as a (centrosymmetric) dicationic homotrimer via a close cofacial association of a pair of cationic and one neutral molecule of 1 with an interplanar separation of ～3.2 A. The structure of the dicationic homotrimer was also reproduced by DFT calculations. Furthermore, the structure of a dicationic spiro adduct, formed by a slow decomposition of a solution of 1~(+·) SbCl_6~-, was also established by X-ray crystallography.