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

Abstract

The reaction of Schiff base ligand N,N0-bis(salicylidene)ethylenediamine (H2L) with [CoII 2(m- OH2)(O2CCMe3)4(HO2CCMe3)4] (CoII 2-Piv) (Piv = pivalate) and Ln(NO3)3 xH2O (for 1, 3, 4 x = 5; for 2, x = 6) salts in the presence of triethylamine afforded [CoIIILnIII(L)(m-Piv)2(Z1-Piv)2(Z1-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 Z1-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 zerofield at low temperatures whereas compound 4 displays field-induced slow magnetic relaxation. This phenomenon is in agreement with the results of theoretical studies.