A novel manganese(II) coordination polymer with azide and neutral dicarboxylate ligands: helical structure and magnetic properties.

By using a neutral inner-salt-type dicarboxylate as coligand, a novel two-dimensional (2D) manganese(II) coordination polymer, [Mn(L)(N(3))]ClO(4) x 1/2 H(2)O (L = 1,3-bis(3-carboxylatopyridinium)propane), was synthesized, and characterized by X-ray crystallography and magnetic measurements. The compound contains uniform Mn(II) chains with simultaneous azide and carboxylate bridges between adjacent Mn(II) ions. The formally negative chains are interlinked by the positively-charged 1,3-bis(pyridinium)propane spacer, and the spiral conformation of the spacer imports intriguing helical features to the resulting 2D network, in which [MnL] helices are connected by sharing metal centers with alternating centro- and C(2)-symmetry. The triple (azide)bis(carboxylate) bridge mediates overall antiferromagnetic coupling with J = -3.0 cm(-1), as a result of the competition between the antiferromagnetic (carboxylate) and ferromagnetic (azide) pathways.