Effect on the geometry over the slow relaxation of the magnetization in a series of erbium(iii) complexes based on halogenated ligands

Abstract

We report the synthesis, crystal structures, and magnetic and theoretical investigations of five erbium complexes based on halogenated ligands with the respective formulas trans-[Er(L¹)₃(THF)₂] (1), trans-[Er(L²)₃(Ph₃PO)₂] (2), fac-[Er(L³)₃(THF)₃] (3), fac-[Er(L⁴)₃(Ph₃PO)₃] (4), and [Er(L⁵)₃] (5) (L¹ = OCPh₂(CF₂Cl), L² = OCPh(CF₃)₂, L³ = OCH(C₆F₅)₂, L⁴ = OCHMe(C₆F₅), L⁵ = 1,8-dibromo-3,6-di-tert-butylcarbazol-9-ide, THF = tetrahydrofuran). Modulation of the experimental conditions allows controlling the coordination geometry of the resulting complexes. While 1 and 2 adopt a trigonal bipyramidal geometry, 3 and 4 exhibit a distorted octahedral arrangement. In contrast, 5 exhibits a triangular coordination geometry. Magnetic investigations in line with theoretical calculations reveal that only the three-coordinated complex 5 exhibits a zero-field slow relaxation of the magnetization, while compound 1 demonstrates field-induced relaxation dynamics.