Exploiting complementary ligands for the construction of square antiprismatic monometallic lanthanide SMMs

Abstract

The methylation of p-tert-butylcalix[4]arene in the distal 1,3-phenolic sites provides the ligand H₂L = {p-tert-butylcalix[4](OMe)₂(OH)₂arene} that enables construction of heteroleptic mononuclear lanthanide complexes. The reaction of (N(nBu)₄)(acac) (Hacac = acetylacetone), M^IIICl₃ and H₂L under Schlenk conditions results in the formation of a family of (N(nBu)₄)[M^IIIL(acac)₂] complexes where M = Y (1), Gd (2), Tb (3) and Dy (4). The metal ions are eight-coordinate in distorted square-antiprismatic coordination geometries, resulting in slow relaxation of the magnetisation for the Tb derivative.