A fresh look at the structural diversity of dibenzoylmethanide complexes of lanthanides

Abstract

An analysis of known synthetic methods for dibenzoylmethanide (dbm⁻) complexes of lanthanides of different nuclearity, viz. [Ln(dbm)₃(H₂O)], [Ln₄(dbm)₁₀(OH)₂], [Ln₅(dbm)₁₀(OH)₅] and [KLn(dbm)₄]_n (Ln = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) has been carried out. These methods have been optimized, the range of lanthanides for the compounds extended, and novel complex species, viz. [KLn(Me₂CO)(dbm)₄]₂ (Ln = Eu, Dy, Yb) and [Nd₃(dbm)₈(OH)(H₂O)], have been produced. The nature of the lanthanides in some cases affects the composition of the products formed. The compound [KEu(Me₂CO)(dbm)₄]₂ in solution can transform to [KEu(dbm)₃(OBz)]_n, containing benzoate (OBz⁻). For the seven new complexes, the crystal structures have been determined by X-ray diffraction. Photoluminescent properties of the europium complexes have been studied. Their composition and structure influence the emission band shape and quantum yields. Two solid solutions of heterolanthanide complexes [Er_xYb_5–x(dbm)₁₀(OH)₅] (x = 1.2, 2.0) have been prepared, as shown by high-resolution powder XRD analysis.