Under hydrothermal condition, the reaction of 2,4‐dichlorophenoxyacetic acid (2,4‐DH) and 1,3‐bis(4‐pyridyl)propane with MnCl2 ·2H2O gave a novel metal‐organic framework (MOF), [Mn(2,4‐D)2 (H2O)2] n (1). This complex was characterized by IR, elemental analysis, powder X‐ray diffraction, and thermogravimetry analysis. X‐Ray single‐crystal diffraction shows that the Mn(II) ions are bidendate bridged by carboxyl groups in the syn–anti mode, giving a two‐dimensional (2D) network. Temperature‐dependent magnetic studies reveal that there are weak antiferromagnetic exchange interactions between the Mn(II) ions transmitted by carboxyl groups.