Synthesis, structure and characterisation of Ln5O(OPri)13 with Ln = Nd, Gd or Er

Abstract

The molecular and basically isostructural oxo-alkoxides Ln₅O(OPrⁱ)₁₃ (Prⁱ = 2-propyl) with Ln = Nd (1) and Gd (2) were synthesized by metathesis of LnCl₃ and KOPrⁱ, in combination with stoichiometric hydrolysis, in 2-propanol-containing solvents. Er₅O(OPrⁱ)₁₃3 was obtained as co-product to an erbium aluminium 2-propoxide with an Er ∶ Al ratio of ca. 3 ∶ 1, from the reaction of 15KOPrⁱ + H₂O + Al(OPrⁱ)₃ with 5ErCl₃, in toluene–2-propanol. The solid state structures of 1–3 were obtained by single-crystal X-ray diffraction. The characterisations were made with differential scanning calorimetric measurements, UV-Vis and FT-IR spectroscopy. The molecule contains an M₅O fragment with the configuration of a square pyramid and the oxo-oxygen atom slightly above the basal plane. FT-IR measurements showed that the molecular structure of the alkoxide was retained, to a large extent, when dissolved in toluene–2-propanol (2 ∶ 1) or hexane. Investigations by UV-Vis and FT-IR spectroscopy showed that Ln₅O(OPrⁱ)₁₃ reacted with Al₄(OPrⁱ)₁₂ (Ln ∶ Al = 1 ∶ 3) in toluene–2-propanol to form LnAl₃(OPrⁱ)₁₂ within 2 hours at 80 °C.