Cubane-type {M4O4} (M = CoII, ZnII, CuII) clusters: synthesis, crystal structures, and luminescent and magnetic properties

Abstract

The employment of the hydroxyl-rich ligand (E)-3-((2-hydroxy-3-methoxybenzylidene)amino)propane-1,2-diol (H₃L) in the chemistry of cubane-type {M₄O₄} clusters is reported. Three cubane-type clusters of the formula [M₄(HL)₄] (M = Co^II (1), Zn^II (2), Cu^II (3)) were achieved by reactions of metal acetates with H₃L under solvothermal conditions. The structures of 1, 2 and 3 have been established by single-crystal X-ray diffraction studies. The tetranuclear clusters 1–3 have cubane-type [M₄(μ₃-OR)₄]⁴⁺ cores with divalent metal atoms and deprotonated oxygen atoms (originating from the HL²⁻ ligands) occupying alternate vertices. The luminescence studies suggest strong emission for 2 in the solid state at room temperature. The magnetic properties of 1 and 3 have been investigated. The variable-temperature dc magnetic susceptibility studies indicate ferromagnetic M^II⋯M^II exchange interactions for 1 and 3. The ac magnetic susceptibility investigation reveals that complex 1 shows slow magnetic relaxation (SMM) behavior.