Mixed-Valent Trinuclear Co(III)-Co(II)-Co(III) Complex with 1,3-Bis(5-chlorosalicylideneamino)-2-propanol

A mixed-valent trinuclear complex with 1,3-bis(5-chlorosalicylideneamino)-2-propanol (H(3)clsalpr) was synthesized, and the crystal structure was determined by the single-crystal X-ray diffraction method at 90 K. The molecule is a trinuclear Co(III)-Co(II)-Co(III) complex with octahedral geometries, having a tetradentate chelate of the Schiff-base ligand, bridging acetate, monodentate acetate coordination to each terminal Co(3+) ion and four bridging phenoxido-oxygen of two Schiff-base ligands, and two bridging acetate-oxygen atoms for the central Co(2+) ion. The electronic spectral feature is consistent with the mixed valent Co(III)-Co(II)-Co(III). Variable-temperature magnetic susceptibility data could be analyzed by consideration of the axial distortion of the central Co(2+) ion with the parameters Δ = –254 cm(−1), λ = –58 cm(−1), κ = 0.93, tip = 0.00436 cm(3) mol(−1), θ = –0.469 K, g(z) = 6.90, and g(x) = 2.64, in accordance with a large anisotropy. The cyclic voltammogram showed an irreversible reduction wave at approximately −1.2 V·vs. Fc/Fc(+), assignable to the reduction of the terminal Co(3+) ions.