Dr. Kuirun Zhang, Dr. Soonchul Kang, Dr. Zi‐shuo Yao, Kazusa Nakamura, Dr. Takashi Yamamoto, Prof. Dr. Yasuaki Einaga, Nobuaki Azuma, Dr. Yuji Miyazaki, Prof. Dr. Motohiro Nakano, Dr. Shinji Kanegawa, Prof. Dr. Osamu Sato


Heterometallic Prussian blue analogues are known to exhibit thermally induced charge transfer, resulting in switching of optical and magnetic properties. However, charge‐transfer phase transitions have not been reported for the simplest FeFe cyanide‐bridged systems. A mixed‐valence FeII/FeIII cyanide‐bridged coordination polymer, {[Fe(Tp)(CN)3]2Fe(bpe)⋅5 H2O}n, which demonstrates a thermally induced charge‐transfer phase transition, is described. As a result of the charge transfer during this phase transition, the high‐spin state of the whole system does not change to a low‐spin state. This result is in contrast to FeCo cyanide‐bridged systems that exhibit charge‐transfer‐induced spin transitions.