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(N ₃)₂] (1) and [Ni(5-methylpyrazole)₄(N ₃)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.