Synthesis, Characterization, Magnetic Properties, and DFT Investigations of Heterobimetallic Nickel–Lanthanide LNi^IILn^III (Ln = Ce, Gd, Tb, Dy) Complexes Supported by Schiff Base Ligands

Abstract

Four Schiff base complexes LNiLn (Ln = Ce ( 2 ), Gd ( 3 ), Tb ( 4 ), and Dy ( 5 ), H 2 L= N,N′‐bis(3‐methoxysalicylaldiimine)‐1,3‐propylene‐2‐ol)) are synthesized from the precursor LNi ( 1 ) moieties. However, compound 2 , which crystallizes in the tetragonal system, differs from the other isostructural three 3 , 4 , and 5 congeners. The dc magnetic studies reveal ferromagnetic interaction between the Ni(II) (S = 1) and the trivalent lanthanide (Ln(III) = Gd, Tb, and Dy) but not for Ce(III) in agreement with the computational results. The dynamic magnetic investigations highlight field‐induced single‐molecule magnet behaviors at 2 K for Ln(III) = Ce, Tb, and Dy. In case of compound 4 , it is determined that the slow magnetic relaxation occurs through an Orbach process only with Δ = 19.1(3) K and τ 0 = 3.99(4) × 10 −7 s (H = 1200 Oe). Electronic structures and magnetic properties have been investigated theoretically using relativistic density functional theory calculations combined with the broken symmetry approach for the magnetic properties. The results indicate a Ferro character for 3 (+1.03 cm −1 ), 4 (+5.44 cm −1 ), and 5 (+1.35 cm −1 ), and an antiferromagnetic (AF) behavior for complex 2 (−2.82 cm −1 ) , in agreement with experimental magnetic susceptibility measurements. Moreover, the computed Mayer and Nalewajski–Mrozek Ni(II)–O b and O b –Ln(III) bond orders are found to be higher for 2 than for 3 , 4 , and 5 , correlating well with the AF and Ferro character of each species.