Novel octadecanuclear copper(II)–lanthanoid(III) clusters. Synthesis and structures of [Cu12Ln6(µ3-OH)24(O2CCH2CH2NC5H5)12(H2O)16(µ12-ClO4)][ClO4]17·16H2O (LnIII= GdIII or SmIII)

Abstract

Two octadecanuclear clusters [Cu₁₂Ln₆(µ₃-OH)₂₄(O₂CCH₂CH₂NC₅H₅)₁₂(H₂O)₁₆(µ₁₂-ClO₄)][ClO₄]₁₇·16H₂O (Ln^III= Gd^III or Sm^III) have been synthesized and characterized by X-ray structural analysis. The clusters are isostructural, crystallizing in the triclinic space group P with Z= 1. In each structure six Ln^III are positioned at the vertices of an octahedron with twelve Cu^II at the midpoints of the edges of the octahedron. The 24 OH^– groups act as µ₃ bridges each ligating one Ln^III and two Cu^II. The octahedron encapsulates an unusual µ₁₂-ClO₄^– anion of which each oxygen atom co-ordinates to three Cu^II at the axial positions. Ten of the C₅H₅N⁺CH₂CH₂CO₂^– ligands act in the µ-carboxylato-O,O′ mode, while the other two act in the carboxylato-O,O′ mode each chelating a Ln^III, resulting in different co-ordination environments for the Cu^II and Ln^III.