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

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 (L ¹) and 1-(carboxylatoethyl)-4-(5-tetrazolato)pyridinium (L ²), were synthesized, and structurally and magnetically characterized. They are formulated as [Mn ₃(L ¹) ₂(N ₃) ₄(H ₂O) ₂] _n·4nH ₂O (1) and [Mn ₃(L ²) ₂(N ₃) ₄(H ₂O) ₃] _n·3.5nH ₂O (2). In both compounds, octahedral Mn ^II ions are linked by the mixed (μ ₂-EO-N ₃)(μ ₂-syn,syn-COO) (μ ₂-N ²,N ³-CN ₄) (CN ₄ = tetrazolate and EO = end-on) triple bridges to give anionic linear trinuclear motifs. The motifs are connected through EE-N ₃ (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 CdSO ₄-type topology, respectively. Magnetic studies demonstrated that the magnetic interactions within and between the trinuclear motifs, through the tricomponent and EE-N ₃ bridges, respectively, are both antiferromagnetic in both compounds.