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High-Spin Polymers: Ferromagnetic Coupling of <i>S</i> = 1 Hexaazacyclophane Units up to a Pure <i>S</i> = 2 Polycyclophane
Triarylamines oxidized
to radical cations can be used as stable
spins sources for the design of high-spin compounds. Here, we present
the synthesis of the polyarylamine-containing hexaazacyclophanes linked
via <i>meta</i>-terphenyl bridges. Spins, created after
oxidation of the polymer, can be coupled magnetically in cyclophane
moieties via <i>meta</i>-phenyl and along the polymer chain
via <i>meta</i>-terphenyl units. The formation of a quintet
spin state was evidenced by pulsed-EPR nutation spectroscopy. Two
exchange coupling constants via both couplers were determined experimentally
and corresponded to <i>J</i>/<i>k</i> = 89 K in
the cyclophane moiety and <i>j</i>/<i>k</i> =
17 K via <i>meta</i>-terphenyl. Most importantly, in this
polymer, four spins can be ferromagnetically ordered via both couplers,
which leads to the high spin state