Ferromagnetic interactions through double hydrogen bonding bridges in manganese(II) coordination polymers.

Three isostructural Mn(II) compounds with a zwitterionic dicarboxylate ligand and different pseudohalides were synthesized, and then structurally and magnetically characterized. They are formulated as [Mn(L)(X)(2)(H(2)O)(2)](n) [X = N(3)(-) (1), NCO(-) (2), NCS(-) (3), L = 1,4-bis(4-carboxylato-1-pyridinium)butane]. In these compounds, adjacent Mn(II) ions are connected into coordination chains by long zwitterionic linkers and into hydrogen-bonded chains by short double O-H···N bridges involving coordinated water and pseudohalide ligands. Magnetic studies revealed for the first time that the double hydrogen bridges induce ferromagnetic coupling between the Mn(II) ions.