Synthesis, crystal structure and magnetism of a single-molecule magnet, [Mn16O16(OMe)6(OAc)16(MeOH)3(H2O)3] . 6H2O, and of a mixed bridge 1D chain, [Mn(micro-OMe)(micro-OAc)2]n

The syntheses, structures and magnetic characterisations of the hexadecanuclear manganese(III/IV) carboxylate cluster [Mn16O16-(OMe)(6)(OAc)(16)(MeOH)(3)(H2O)(3)]center dot 6H(2)O(1 center dot 6H(2)O) and a linear chain Mn-III complex [Mn(mu-OMe)(mu-OAc)(2)](n) (2) are reported. AC magnetic susceptibility measurements confirm 1 to be a single-molecule magnet with relaxation parameters of tau(0) = 3.00 x 10(-9) s and energy barrier, Delta E, of 52.2 cm(-1). Complexes 1 center dot 6H(2)O and 2 were obtained by reaction of n-BU4NMnO4 with Mn(NO3)(2)center dot 4H(2)O in a mixture of methanol and acetic acid. Complex 1 center dot 6H(2)0 crystallises in the triclinic space group P(1)over-bar and the cluster structure consists of six Mn-IV and 10 Mn-III ions held together by 14 mu(3)-O2-, two mu(2)-O2-, four mu(2)-OMe- and two mu(2)-OAc- groups to give a roughly elliptical planar [Mn16O16(OMe)(4)(OAc)(2)](16+) core. Peripheral ligation consists of the remaining 14 mu(2)-OAc-, two mu(2)-OMe- groups and three axial water and methanol molecules. Complex 2 crystallises in the orthorhombic space group Pbcn and consists of infinite linear ID chains of manganese(III) atoms bridged by two mu-OAc- ligands and one mu-OMe-. The magnetic data on 1 center dot 6H(2)O and 2 are compared with those of other recently reported Mn-16 and Mn(III) mu-carboxylate chain analogues. (c) 2006 Elsevier Ltd. All rights reserved.