Resonance Balance Shift in Stacks of Delocalized Singlet Biradicals (pages 5482–5486)
Akihiro Shimizu, Mikio Uruichi, Kyuya Yakushi, Hiroyuki Matsuzaki, Hiroshi Okamoto, Masayoshi Nakano, Yasukazu Hirao, Kouzou Matsumoto, Hiroyuki Kurata and Takashi Kubo
Article first published online: 22 JUN 2009 | DOI: 10.1002/anie.200901382
Two flavors: Intra- and intermolecular spin–spin interactions of unpaired electrons coexist and correlate in stacks of phenalenyl-based singlet biradicals. The electronic structure of the one-dimensional π–π chain is best represented by the superposition of formulas A and B in terms of the resonating valence-bond (RVB) model. Lower temperatures and higher pressures induce a resonance balance shift to the formula B.