Novel phenoxo-bridged di- and tri-nuclear Cu(II) salamo-like complexes driven by various counter-anions

Abstract

A N2O3-donor aldehyde-appended salamo-like ligand H2L has been designed and synthesized successfully, and can be used to prepare [{Cu(L)}2] (1) and [Cu3(L)2(EtOH)2]·2ClO4 (2) with different nuclearity and extraordinary structures by changing the reaction conditions (various counter-anions and solvent molecules). In addition, the structures of two complexes were determined by single-crystal X-ray diffraction experiments. The results showed that complex 1 is a novel (L)2−: Cu(II) = 1:1 non-centrosymmetrical homobinuclear dimeric Cu(II) complex, where Cu1 sited in the N2O2-donor position also coordinates with one phenolic oxygen atom of another ligand (L)2− moiety to construct two discrete metal–ligand [Cu(L)] units. However, Noteworthy, the influence of the interaction of multiple counter-anions and solvents led to the formation of a novel (L)2−: Cu(II) = 2:3 homotrinuclear centrosymmetric sandwich-like dimeric structure in complex 2, where Cu2 located at the O6 position bridges two [Cu(L)(EtOH)] metalated ligand moieties. Finally, two novel homopolynuclear dimeric Cu(II) complexes were characterized by elemental analysis, coordination cavities analyses, infrared spectroscopy (IR), electrostatic potential analyses (ESP), interaction region indicator (IRI) analyses and DFT calculation, UV–vis, luminescence spectroscopy and Free regions analyses.