Octanuclear MnIII6MnII (Ln = Gd, Dy and Er) clusters with a novel core topology: syntheses, structures, and magnetic properties

Reactions of [Mn6O2(piv)(10)(py)(2.5)(piv)(1.5)], Ln(NO3)(3)-6H(2)O and N-mdeaH(2) in MeCN in the presence of Me3SiCl generated a family of octanuclear Mn/Ln complexes [Mn(6)(III)Mn(II)Ln(N-mdea)(3)(N-mdeaH) (piv)(8)O-2(OH)(3)(NO3)(H2O)]center dot x CH3CN center dot xH(2)O [Ln = Gd (1), Dy (2), Er (3), pivH = pivalic acid, N-mdeaH(2) = N-methyl diethanolamine]. Each complex possesses a [Mn(6)(III)Mn(II)Ln(mu(3)-O)(2)(mu(3)-OH)(3)](16+) core containing two butterfly-like subunits of [Mn(3)Ln(mu 3-OH)(2)] and [Mn-4(mu 3-O)(2)] sharing a common vertex, and an outer Mn atom ligated to one of the subunits through a mu(3)-OH- ligand. The core topology represents a new Mn/Ln core type. The magnetic susceptibility study of 1-3 indicates the presence of dominant anti-ferromagnetic interactions within the complexes. For complex 1, which contains an isotropic Gd-III atom, fitting of the obtained M/(N mu(B)) 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 3 exhibits out-of- phase ac susceptibility signals, indicating it may be a SMM.