Structural and spectroscopic studies on 36-membered ring arrays formed by copper(II) halides with 1-(4-picolyl)pyrrolidin-2-one

Abstract

Reaction of 1-(4-picolyl)pyrrolidin-2-one (ppo) with hydrated copper(II) chloride or bromide in methanol affords the compounds [Cu(ppo)₂X₂](X = Cl or Br). A single-crystal X-ray diffraction study of [Cu(ppo)₂Br₂]1 shows that the ppo molecule acts as a bridging ligand with the formation of all trans-CuBr₂N₂O₂ units linked to produce sheets of contiguous 36-membered rings. The EPR spectra of 1 and its chloride analogue give well resolved rhombic-type spectra. The EPR and electronic spectra of [Cu(ppo)₂X₂](X = Cl or Br) are analysed in terms of angular-overlap bonding parameters. X-Ray studies show that the compound [Cu₄OCl₆(ppo)₄] comprises a Cu₄(µ₄-O)Cl₆ core with an N-bonded ppo ligand co-ordinated to each Cu atom.