Two Polynuclear Manganese(II) Complexes Based on Multidentate N-Heterocyclic Aromatic Ligand and V-Shaped Polycarboxylate Ligand: Synthesis, Crystal Structure Analysis and Magnetic Properties

Abstract

The reaction of MnCl2, 2-(5-{6-[5-(Pyrazin-2-yl)-1H-1,2,4-triazol-3-yl]pyridin-2-yl}-1H-1,2,4-triazol-3-yl)pyrazine (H2ptptp), 4,4′-sulfonyldibenzoic acid (H2sdba) or 4-(4-carboxyphenoxy)phthalate acid (H3cpop) and [BMI]Br ionic liquids (BMI = 1-butyl-3-methylimidazolium) gave rise to two complexes, {[Mn4(ptptp)2(sdba)2(H2O)2]·2H2O}n (1) and {[Mn3(ptptp)(cpop)Br(H2O)2]·2H2O}n (2). The compounds have been well characterized by elemental analysis, IR spectra, thermogravimetric analysis, as well as single-crystal and powder X-ray diffraction. The structure feature of 1 is that Mn(II) ions in the [Mn6(sdba)2] loops of V-shaped sdba2− ligands are ptptp2− ligands, respectively, and a 2D layer is constructed from sdba2− and ptptp2− ligands. The adjacent 2D layers are connected by O–H⋯N hydrogen bonds to form a 3D supramolecular network. The neighbouring trinuclear Mn(II) clusters in 2 are linked by V-shaped cpop3− ligands to give a 2D layer, which is penetrated by ptptp2− ligands to form self-threading structure. The results of variable-temperature magnetic studies have shown that the magnetic interactions between the Mn(II) ions in 1 and 2 are mainly due to antiferromagnetic coupling.