Methylpyrazole-Capped Two-Dimensional Supramolecular M(II) (M = Mn, Ni, Co) Assemblies Constructed by Covalent and Noncovalent Interactions: Uncommon Coordination Modes of Methylpyrazoles and Magnetic Properties

Two mononuclear complexes [Mn(5-methylpyrazole)4(N3)2] (1) and [Ni(5-methylpyrazole)4(N3)2] (2), as well as a novel one-dimensional coordination polymer [Co(3-methylpyrazole)2(5-methylpyrazole)2(tp)]n (3) (tp = terephthalate), were characterized. The isostructural complexes, 1 and 2, display two-dimensional supramolecular networks formed by hydrogen bonds between the N−H groups of 5-methylpyrazoles and the end N atoms of the azide ligands and additional face-to-face π−π interactions of the 5-methylpyrazoles. For 3, tp-bridged one-dimensional chains assisted by intrachain hydrogen bonds among the N−H groups of methylpyrazoles and carboxylate oxygens are connected with the help of interchain C−H···O hydrogen bonds, leading to a two-dimensional structure. The intra- and interchain hydrogen bonds account for the coexistence of two unique coordination forms (5-methylpyrazole and 3-methylpyrazole) of methylpyrazoles in the same coordination sphere. Weak antiferromagnetic interactions coupled with the spin−orbit coupling effect are operative in 3 through the tp ligands.