SummaryReactions of [2,]cyclophanes (N = 2,. . .6) with solvated electrons in 1,2-dimethoxyethane at 193 K have been studied by ESR. and ENDOR. spectroscopy. All but the two most highly bridged cyclophanes ( N = 5 and 6) are reduced to paramagnetic species under these conditions. Whereas the radical anions of [2.2]-paracyclophane and p3] (1,2,4)-and p4] (1,2,4,5)cyclophanes are sufficiently persistent to be characterized by their hyperfine data, those of the remaining five cyclophanes undergo a rapid cyclization to the radical anions of4,5,9,10-tetrahydropyrenes. These have been identified as the unsubstituted tetrahydropyrene (from [2.2]-metacyclophane and [23] (1,2,3)cyclophane), the 2,7-dimethyl-derivative (from [2,] (1,3,5)-and p4] (1,2,3,5)cyclophanes) and the 1,8-dimethyl-derivative (from [24] (1,2,3,4)cyclophane). The persistence of the cyclophane radical anions seems to depend on the numbers, nmeta and npa,a, of the meta-and para-positions of the bridging ethano groups in the two benzene rings. The prerequisite for the radical anion to be persistent is nmeta 6 npara.