Hydrolytic synthesis and structural characterization of lanthanide-acetylacetonato/hydroxo cluster complexes – A systematic study

Abstract

Lanthanide hydroxide cluster complexes with acetylacetonate were synthesized by the hydrolysis of the corresponding hydrated lanthanide acetylacetonates in methanol in the presence of triethylamine. Polymeric lanthanide hydroxide complexes based on diamond-shaped dinuclear repeating units of [Ln₂(CH₃CO₃)₂]⁴⁺ (Ln = La, Pr) and discrete complexes featuring a tetranuclear distorted cubane core of [Ln₄(μ₃-OH)₂(μ₃-OCH₃)₂]⁸⁺ (Ln = Nd, Sm) and a nonanuclear core of [Ln₉(μ₄-O)(μ₄-OH)(μ₃-OH)₈]¹⁶⁺ (Ln = Eu–Dy, Er, Yb) were obtained. The dependence of the cluster nuclearity on the identity of the lanthanide ion is rationalized in terms of the influences of a metal ion's Lewis acidity and the sterics about the Ln–OH unit on the kinetics of the assembly process that leads to a particular cluster.