Synthesis, crystal structure and magnetic properties of single-molecule magnet: [Mn4(CF3COO)4(hmp)6]

The preparation, X-ray structure and magnetic properties are presented for a new mixed-valence tetranuclear manganese complex that functions as a single-molecule magnet (SMM): [Mn₄(CF₃COO)₄(hmp)₆], where hmp^? is the anion of 2-(hydroxymethyl) pyridine and is a N,O bidentate chelate. The compound crystallizes in a monoclinic system, space group P ₂₁/c (No. 14) with unit cell parameters a = 13.663(3) Å, b = 14.705(3) Å, c = 14.734(3) Å, β = 98.51(3)°, V = 2927.6 ų and Z = 2. The structure of the complex shows a novel coordination of the trifluoroacetate (TFA) anions, with one anion acting as a monodentate ligand while the second one coordinating through both oxygens to the same Mn center. Direct current magnetic susceptibility measurement in the 2–300 K temperature range supports a high-spin ground state. The presence of a frequency-dependent alternating current susceptibility signal indicates that the individual molecule is acting as magnet.