Manganese(II) coordination polymer with simultaneous azide, tetrazolate and carboxylate bridges: Synthesis, structure and magnetism

The reaction of a pyridinium-containing ligand precursor with manganese(II) chloride and sodium azide yielded a Mn(II) coordination polymer, [MnLN ₃]_n·1.5nH₂O, where L is 1-(tetrazolato-5-methyl)pyridinium-4-carboxylate, a bifunctional zwitterionic ligand generated in situ from a non-coordinative precursor via two organic reactions (cyano-to-azide cycloaddition and ester hydrolysis). In the compound, metal ions are connected into uniform chains by the triple bridges consisting of μ-1,1-azide, μ-2,3-tetrazolate and μ-1,3-carboxylate, and the formally anionic chains are charge compensated and interlinked into 2D layers by the cationic 1-methylenepyridinium backbone of the L ligand. The compound displays typical 1D antiferromagnetism with J = - 2.37 cm^{- 1} through the triple bridges. Magneto-structural analysis indicates the antiferromagnetic interaction increases as the Mn-N-Mn angle of the azide bridge decreases.