A new linear chain complex of oxo-centered trinuclear manganese clusters, [{(Mn2MnO)-Mn-III-O-II(O2CCHCl2)(6)(H2O)}{Mn-(O2CCHCl2)(2)(H2O)(4)}](n) (1), has been synthesized by treatment of a mixture of Mn(OAC)(2).4H(2)O and dichloroacetic acid in dichloromethane with KMnO4, In this complex chains are formed by hydrogen bonding between carboxylate oxygens and coordinated water molecules, forming a two-dimensional structure. Antiferromagnetic coupling was observed by variable-temperature magnetic measurements. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.