Octanuclear Mn(III)6Mn(II)Ln (Ln = Gd, Dy and Er) clusters with a novel core topology: syntheses, structures, and magnetic properties.

ABSTRACT

Reactions of [Mn6O2(piv)10(py)2.5(piv)1.5], Ln(NO3)3·6H2O and N-mdeaH2 in MeCN in the presence of Me3SiCl generated a family of octanuclear Mn/Ln complexes [Mn6(III)Mn(II)Ln(N-mdea)3(N-mdeaH)(piv)8O2(OH)3(NO3)(H2O)]·xCH3CN·xH2O [Ln = Gd (1), Dy (2), Er (3), pivH = pivalic acid, N-mdeaH2 = N-methyl diethanolamine]. Each complex possesses a [Mn6(III)Mn(II)Ln(µ3-O)2(µ3-OH)3](16+) core containing two butterfly-like subunits of [Mn3Ln(µ3-OH)2] and [Mn4(µ3-O)2] sharing a common vertex, and an outer Mn atom ligated to one of the subunits through a µ3-OH(-) ligand. The core topology represents a new Mn/Ln core type. The magnetic susceptibility study of 1-3 indicates the presence of dominant antiferromagnetic interactions within the complexes. For complex 1, which contains an isotropic Gd(III) atom, fitting of the obtained M/(NµB) vs. H/T data gave S = 4, g = 1.90, and D = -0.31 cm(-1). The results were further supported by ac data. Complex exhibits out-of-phase ac susceptibility signals, indicating it may be a SMM.