Magnetic and Electrochemical Properties of Lantern-Type Dinuclear Ru(II,III) Complexes with Axial Chloride Ions or Water Molecules

Makoto Handa , Haruki Yairi, Natsumi Yano, Minoru Mitsumi, Hiroshi Sakiyama, Masaharu Kitashima, Kazuhito Inoue, Ryoji Mitsuhashi, Masahiro Mikuriya, Haruo Akashi and Yusuke Kataoka

By using [Ru2(O2CC3H7)4Cl]n (1) as a starting material, nBu4N[Ru2(O2CC3H7)4Cl2] (nBu4N+ = tetra(n-butyl)ammonium cation) (2) and [Ru2(O2CC3H7)4(H2O)2]BF4 (3) were prepared. The lantern-type dinuclear structures with axial chloride ions or water molecules were confirmed for 2 and 3 by X-ray crystal structure analyses. The crystal structures of 2 and 3 were compared with that of 1. In the crystal of 2, there were three crystallographically different dinuclear units; the Ru–Ru distances of each unit were 2.3094(3), 2.3046(4), and 2.3034(4) Å, respectively, which were longer than those of 1 (2.281(4) Å) and 3 (2.2584 (7) Å). Temperature dependent magnetic susceptibility measurements were performed for 1 and 2 as well as 3. The effective magnetic moments (µeff) at 300 K were 3.97 (for 1), 4.00 (for 2), and 3.97 µB (for 3), respectively. The decreases in the µeffvalue were confirmed for all of the complexes due to the large zero-field splitting (D): D = 68 cm−1 for 1, 78 cm−1 for 2, and 60 cm−1 for 3. Cyclic voltammograms measured in CH2Cl2 with a electrolyte of nBu4N(BF4) showed the Ru25+/Ru24+ process at −0.2–−0.4 V (vs. SCE) and the Ru26+/Ru25+ one at 1.3–1.4 V (vs. SCE), of which potentials were confirmed by the DFT calculation for nBu4N[Ru2(O2CC3H7)4Cl2].

Magnetochemistry

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doi.org/10.3390/magnetochemistry5010018