Stable Triplet-State Di(Cation Radicals) of a Meta−Para Aniline Oligomer by “Acid Doping”

We describe the formation of a stable triplet-state oligoaniline di(cation radical) via a proton-triggered redox reaction between N,N ‘-bis[4-(phenylamino)phenyl]-1,3-benzenediamine ( 1 ) and N,N ‘-bis[4-(phenylimino)-cyclohexa-2,5-dienylidene]-1,3-benzenediamine ( 2 ). In this reaction 1 is oxidized, while protonated 2 is reduced, both yielding the same di(cation radical) 1 2 • 2+ . The di(cation radical) is characterized with UV/visisble/near-IR and ESR spectroscopy ( D = 118 MHz; E ≈ 0 MHz). Variable-temperature ESR measurements are consistent with a triplet ground state for 1 2 • 2+ . The high stability of 1 2 • 2+ under ambient conditions demonstrates that alternating meta and para oligoanilines are interesting building blocks for future polaronic ferromagnets.