Lanthanide Complexes (Ln=La, Nd, Dy) of Octaethyl propane‐1,1,3,3‐tetrayltetrakis(phosphonate): Multidentate Binding Competing with Monodentate DMSO Complexes

Abstract

The preparation of lanthanide nitrate complexes [Ln(NO3)3{L}]n (Ln3+=La, Nd, Dy) supported by the octaethyl propane‐1,1,3,3‐tetrayltetrakis(phosphonate) (L) chelate ligand platform is presented. Re‐crystallization of these compounds from DMSO/THF led to a complete replacement of the multidentate phosphonate ester ligand and the formation of exclusively DMSO‐supported lanthanide nitrate species [Ln(NO3)3(DMSO)4]. The relative basicity of a model phosphonate ester vs. DMSO is explored with theoretical means, pointing out the relevance of solvation in this case in line with the experimentally observed exchange process. The optical properties of the dysprosium(III) derivatives are examined in the visible region indicating a significantly higher quantum yield for its tetraphosphonic ester complex than for the DMSO coordinated analog.