Dimeric Radical Cation of 4,5,7,8‐Tetramethyl[2.2]paracyclophane

Abstract
Electrolytic oxidation of 4,5,7,8‐tetramethyl[2.2]paracyclophane (I) yields a paramagnetic species which by ESR. spectroscopic evidence must be ascribed to the dimeric radical cation I2 · ⊕. Analogous dimers are obtained from the 12, 13, 15, 16‐tetradeuterio‐ and 1, 1, 10, 10, 12, 13, 15, 16‐octadeuterio‐derivatives of I so that all coupling constants can be unequivocally assigned to sets of equivalent protons. The hyperfine data for I2 · ⊕ are consistent with an effective D2h or D2d symmetry, the four benzene rings lying in parallel planes.