3,4′-bis[bis(t-butyl- and methoxy-phenyl)amino]stilbene bis(cation radical)s and their electrochemical and magnetic properties

3,3'-Bis[bis(p-t-butylphenyl)amino]stilbene 1a and 3,4'-bis[bis(p-methoxyphenyl)amino]stilbene 1b were synthesized. The oxidation of 1 was analyzed by electrochemical measurements, which revealed the reversible formation of the bis(cation radical) 2 via a two-electron transfer reaction. The chemical oxidation of 1 with NOBF4 also gave the bis(cation radical) 2; UV/vis and ESR spectroscopies supported aminium radical formation without any side reaction. Magnetization, magnetic susceptibility, and the ESR Delta M-s = +/-2 signal of the biradicals indicated tripler ground states with a large triplet-singlet energy gap.