A new mixed-valence hexanuclear manganese(II,III) complex, [Mn6O2(O2CPh)(8)(L)(3)] (HL = 1-phenyl-3-pyridin-2-ylpropane-1,3-dione), has been synthesized and characterized structurally and magnetically. The complex contains a new [(Mn3Mn3O2)-Mn-II-O-III](II+) structural topology. The frequency dependence of out-of-phase component in alternating current magnetic susceptibilities for the complex indicates superparamagnetic behavior.