Formation of oligomeric lanthanide complexes with new tripodal poly(imino carboxylate) ligands

Abstract

Reaction of hydrated lanthanide(III) chloride (LnCl₃·6H₂O) with tris-(2-aminoethyl)amine and the sodium salt of an α-ketocarboxylic acid afforded the trinuclear species [(LnL)₂Na]⁺ which, on removal of Na⁺, aggregate further in MeOH to yield the neutral eight-co-ordinate cyclic tetranuclear species [Ln₄(L¹)₄] (Ln = Yb^III or Y^III), and the linear polymer [Y₂(L²)₂(MeOH)]_∞ with alternating eight- and nine-co-ordinate Y^III centres: recrystallisation of adducts of [L¹]^3– from H₂O affords the nine-co-ordinate mononuclear species [Ln(L¹)(OH₂)₂] (Ln = Sm^III or Gd^III).