Abstract (PDF) Graphical Abstract: Mixed-valent trinuclear manganese complex with N,N’-bis(2-hydroxy-3,5-dimethylbenzyl-N,N’-dimethyl-1,2-ethanediamine (H2hdde), [Mn3(hdde)2(CH3CO2)2(CH3O)2], was synthesized. The X-ray crystal structure analysis revealed a linearly arrangement of MnIII-MnII-MnIIIcore, where a ferromagnetic coupling (J = 2.62 cm–1) between the MnIII and MnII ions.