A new tetrathiafulvalene derivative 1 bearing a single pyridine group and its coordination complex 2, with stoichiometry [Mn(mu-Cl)Cl-(1)(2)(CH3OH)],, have been synthesized and fully characterized. The complex 2 shows an extended chain structure, which is potentially favorable for electrical conductivity. Notably, this is the first monohalogen-bridged Mn(II) polymer exhibiting a moderate antiferromagnetic coupling between the Mn(II) centers.