Three-dimensional networks based on trinuclear motifs with tricomponent azide-carboxylate-tetrazolate cobridges: synthesis, structure and magnetic properties

Abstract

Two 3D coordination polymers of Mn^II with azide and bifunctional zwitterionic ligands bearing both carboxylate and tetrazolate groups, 1-(carboxylatomethyl)-3-(5-tetrazolato)pyridinium (L¹) and 1-(carboxylatoethyl)-4-(5-tetrazolato)pyridinium (L²), were synthesized, and structurally and magnetically characterized. They are formulated as [Mn₃(L¹)₂(N₃)₄(H₂O)₂]_n·4nH₂O (1) and [Mn₃(L²)₂(N₃)₄(H₂O)₃]_n·3.5nH₂O (2). In both compounds, octahedral Mn^II ions are linked by the mixed (μ₂-EO-N₃)(μ₂-syn,syn-COO)(μ₂-N²,N³-CN₄) (CN₄ = tetrazolate and EO = end-on) triple bridges to give anionic linear trinuclear motifs. The motifs are connected through EE-N₃ (EE = end-to-end) bridges to give layers and chains in 1 and 2, respectively, and the cationic pyridinium spacers serve to interlink the layers or chains into three-dimensional frameworks with the α-Po and CdSO₄-type topology, respectively. Magnetic studies demonstrated that the magnetic interactions within and between the trinuclear motifs, through the tricomponent and EE-N₃ bridges, respectively, are both antiferromagnetic in both compounds.