Synthesis, structures and magnetic properties of dysprosium(iii) complexes based on amino-bis(benzotriazole phenolate) and nitrophenolates: influence over the slow relaxation of the magnetization

Abstract

We report the synthesis and crystal structures of four dysprosium(III) complexes based on the amino-bis(benzotriazole phenolate) ligand (^C1NNBiBTP-H₂). While a pentagonal bipyramid complex [Dy(^C1NNBiBTP-H)Cl₂DMF]·THF (1·THF) is obtained in the absence of co-ligands, the association with nitrophenolate derivatives bearing a distinct number and position of nitro groups affords a series of octacoordinated complexes of formulas [Dy(^C1NNBiBTP)L¹(MeOH)₂] (2), [Dy(^C1NNBiBTP)L²(MeOH)₂] (3) and [Dy(^C1NNBiBTP)L³(MeOH)₂] (4) (HL¹ = 2,4-dinitrophenol; HL² = 2,4,6-trinitrophenol; HL³ = 2,5-dinitrophenol). Investigations of the magnetic properties reveal that all the complexes exhibit a field-induced slow relaxation of the magnetization, mainly driven by a Raman relaxation. The observed distinct dynamics could be ascribed to the substituents' influence of the nitrophenolate that affects the Dy–O(phenoxide) distance.