Synthesis, structure, and magnetic properties of diamagnetic Co(iii) ion-based heterometallic CoIII–LnIII (Ln = Dy, Tb, Ho, Er) complexes

Abstract

The reaction of Schiff base ligand N,N′-bis(salicylidene)ethylenediamine (H₂L) with [Co^II₂(μ-OH₂)(O₂CCMe₃)₄(HO₂CCMe₃)₄] (Co^II₂-Piv) (Piv = pivalate) and Ln(NO₃)₃·xH₂O (for 1, 3, 4x = 5; for 2, x = 6) salts in the presence of triethylamine afforded [Co^IIILn^III(L)(μ-Piv)₂(η¹-Piv)₂(η¹-OHMe)₂] [where Ln = Dy, for 1; Tb, for 2; Ho, for 3; and Er, for 4] complexes. The heterometallic dinuclear ensemble is built via the bridging coordination action of [L]²⁻ and four [Piv]⁻ ligands. Further, the Ln(III) center is coordinated by two η¹-OHMe ligands. Shape analysis of all the Ln(III) centers in 1–4 reveals the existence of a distorted triangular dodecahedron geometry. Magnetic studies revealed that compound 1 shows slow magnetic relaxation under zero-field at low temperatures whereas compound 4 displays field-induced slow magnetic relaxation. This phenomenon is in agreement with the results of theoretical studies.