Six nickel-lanthanoid heterometallic complexes based on 2,5-dichlorobenzoate and phen: Syntheses, structures and magnetic properties

Abstract

Six new zero-dimensional (0D) Ni(II)-Ln(III) heterometallic complexes, [Ln2Ni2(2,5-DCB)10(phen)2] [Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5) and Dy (6), 2,5-HDCB = 2,5‑dichlorobenzoic acid, phen = 1,10-phenanthroline], have been successfully synthesized by the reactions of Ln(NO3)3·6H2O, Ni(NO3)2·6H2O, 2,5‑dichlorobenzoic acid, NaOH and 1,10-phenanthroline under solvothermal conditions. All of these complexes have been characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR spectroscopy, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA) and differential thermoanalysis (DTA). Complexes 1–6 are isomorphous and have a linear tetranuclear cluster structure formed by the 2,5-DCB anions linking the Ni(II) and Ln(III) ions. The adjacent tetranuclear molecules are further extended into a two-dimensional (2D) supramolecular architecture by the π–π interactions. The magnetic properties of 1, 2 and 4–6 were investigated in detail. Complex 6 displays a field-induced single-molecule magnet (SMM) behavior with a Ueff value of 10 K.