A Family of $$\left\{ {{\text{Ni}}^{\text{II}}_{2} {\text{Ln}}^{\text{III}}_{2} } \right\}$$ Ni 2 II Ln 2 III Butterfly Complexes: Lanthanide Contraction Effect on the Structures Magnetic Properties

Abstract

Reactions of lanthanide nitrate, nickel nitrate, and polyhydroxyl Schiff-base ligand 2-(((2-hydroxy-3-methoxyphenyl)methylene)amino)-2-(hydroxymethyl)-1,3-propanediol (H4L) gave rise to a family of butterfly heterotetranuclear 3d–4f clusters formulated as [Ln2Ni2(H2L)2(μ3-OCH3)2(CH3CN)2(NO3)4]·2CH3OH·2H2O [Ln = Pr (1), Sm (2), Eu (3), Tb (4), Er (5)]. Single-crystal X-ray diffraction (XRD) reveals these complexes crystallize in the monoclinic space group P21/c. Both Ln1 and its symmetric Ln1A are coordinated to nine oxygen atoms and consist of two ligands with the same coordination mode μ3.η1:η2:η1:η2:η1, two nitrate ions and one μ3-OCH3. The five heterotetranuclear $${\text{Ni}}^{\text{II}}_{2} {\text{Ln}}^{\text{III}}_{2}$$ complexes display a central planar butterfly topology. The vertices of the body positions of the butterfly are occupied by NiII ions in all five complexes, which have been characterized by single-crystal X-ray diffraction, infrared spectroscopy, element analyses, powder X-ray diffraction and thermal gravimetric analyses. The magnetic properties of the complexes have been studied. The results show that complexes 1-3, and 5 exhibit antiferromagnetic exchange between the paramagnetic species, and 4 shows strong ferromagnetic interaction. We have shown the successful design and assembly of a new family of tetranuclear, dicationic, heterometallic $$\left\{ {{\text{Ni}}^{\text{II}}_{2} {\text{Ln}}^{\text{III}}_{2} } \right\}$$ complexes characterized by a butterfly-type topology. The results might be promoting the rational design and synthesis of 3d–4f molecule-base magnets materials with fascinating topologies and magnetic behaviours.