A cascade approach to hetero-pentanuclear manganese-oxide clusters in polyoxometalates and their single-molecule magnet properties

Abstract

Structurally well-defined hetero-pentanuclear manganese-oxide clusters {MMn₄} were successfully synthesized in TBA₇H_n[MMn₄(OH)₂(A-α-SiW₉O₃₄)₂]·2H₂O·C₂H₄Cl₂ (II_MMn4, M = Fe(III), Co(II), Ni(II), Cu(II), Ga(III)) by sequential introduction of metal cations into the trivacant lacunary polyoxometalates (POMs). The pentanuclear manganese-oxide cluster {Mn₅} showed a small spin ground state and a low energy barrier for magnetization relaxation. In contrast, the magnetic interactions in the hetero-pentanuclear clusters could be controlled by the arrangements of metals, and the clusters showed large magnetic anisotropy and single-molecule magnet behavior. In particular, the cluster {FeMn₄} in II_FeMn4 (S = 11/2) showed the slowest relaxation and the highest energy barrier among the previously reported transition metal-containing POMs.