Electron-Transfer Activity in a Cyanide-Bridged Fe42 Nanomagnet

Michael Baker (1) , Shu-Qi Wu , Soonchul Kang , Satoshi Matsuzawa , Marie-Anne Arrio (2) , Yasuo Narumi , Takumi Kihara , Tetsuya Nakamura , Yoshinori Kotani , Osamu Sato , Hiroyuki Nojiri

1 University of Manchester [Manchester]
2 IMPMC - Institut de minéralogie, de physique des matériaux et de cosmochimie

The ability to switch a molecule between different magnetic states is of considerable importance for the development of new molecular electronic devices. Desirable properties for such applications include a large-spin ground state with an electronic structure that can be controlled via external stimuli. Fe 42 is a cyanide-bridged stellated cuboctahedron of mixed-valence Fe ions that exhibits an extraordinarily large S = 45 spin ground state. We have found that the spin ground state of Fe 42 can be altered by controlling the humidity and temperature. Dehydration results in a 15 μ B reduction of the saturation magnetization that can be partially recovered upon rehydration. The complementary use of UV−vis, IR, L 2,3-edge X-ray absorption spectroscopy and X-ray magnetic circular dichroism is applied to uncover the mechanism for the observed dynamic behavior. It is identified that dehydration is concurrent with metal-to-metal electron transfer between Fe pairs via a cyanide π hybridization. Upon dehydration, electron transfer occurs from low-spin {Fe II (Tp)(CN) 3 } sites to high-spin Fe III centers. The observed reduction in magnetization upon dehydration of Fe 42 is inconsistent with a ferrimagnetic ground state and is proposed to originate from a change in zero-field splitting at electron-reduced high-spin sites.

Domains: Chemical Sciences; Theoretical and/or physical chemistry

Michael Baker, Shu-Qi Wu, Soonchul Kang, Satoshi Matsuzawa, Marie-Anne Arrio, et al.. Electron-Transfer Activity in a Cyanide-Bridged Fe42 Nanomagnet. Inorganic Chemistry, 2019, 58, pp.10160 - 10166. ⟨10.1021/acs.inorgchem.9b01216⟩. ⟨hal-03017136⟩