Synthesis, crystal structure and magnetic properties of an enneanuclear manganese cluster containing mixed chelating ligands

Abstract

A new mixed-valence [Mn 9] cluster of formulae [Mn 9O(OH) 3Cl 4(N 3) 3(hmp) 6(dpkd) 3]·1.5CH 3CN·3H 2O ( 1·1.5CH 3CN·3H 2O, where hmp − and dpkd 2− are the anion of 2-hydroxymethylpyridine and the dianion of the gem-diol form of the dpk, respectively) has been synthesized and characterized by single-crystal X-ray diffraction, IR spectra, elemental analysis and magnetic measurements. Single-crystal structural analysis shows that complex 1 contains a [Mn 9] core with a new structural topology in the Mn clusters, in which the centered six Mn III atoms compose a trigonal antiprism and the peripheral residual three Mn II atoms can be seen as the skirt hem of this antiprism. DC magnetic susceptibility studies indicate that the overall antiferromagnetic interactions between Mn ions are present in the cluster. Fitting the data of magnetization and extrapolation of the χ M′ T suggest the spin ground states of S = 3.5, and no out-of-phase ( χ M″) signals are present in the alternating current (AC) susceptibility.