Investigating the effect of lanthanide radius and diamagnetic linkers on the framework of metallacrown complexes

Abstract

By changing the stoichiometric ratios, the one-pot reaction of the glycinehydroxamic acid (H₂glyha) ligand with copper(II) and lanthanide(III) salts in the presence of diamagnetic [Na₂{Fe(CN)₅(NO)}] led to two series of isostructural complexes, which can be designated as heterotrimetallic dimeric clusters [{LnCu₅(glyha)₅}{Fe(CN)₅(NO)}(H₂O)₄]₂·xNO₃·yH₂O (x = 2, y = 11 for La (1), x = 2, y = 11 for Pr (2), and x = 2, y = 11 for Nd (3)) and heterotetrametallic coordination polymers [Na{LnCu₅(glyha)₅}{Fe(CN)₅(NO)}₂(H₂O)_x·yH₂O]_n (x = 6, y = 4 for Sm (4), x = 6, y = 0 for Gd (5), x = 6, y = 4 for Tb (6), x = 5, y = 5 Dy (7), and x = 6, y = 4 for Ho (8)). Each molecular structure contains Ln^III[15-metallacrown-5] nodes and diamagnetic [Fe(CN)₅(NO)]²⁻ linkers. The resulting products demonstrate diversified structural frameworks due to the radius effect of Ln^III ions and different bridging fashions of diamagnetic [Fe(CN)₅(NO)]²⁻ linkers. An analysis of magnetic susceptibilities reveals that 7 exhibits ferromagnetic coupling between Cu^II and Dy^III ions and field-induced SMM behavior.