Synthesis of mono- and heterodinuclear complexes with unsymmetrical phenol-based dicompartmental ligand containing hexa- and tetradentate coordination sites: An unusual methyl elimination in coordination chemistry

Abstract

Novel heterodinuclear complexes type [Zn IILM II] (ClO 4) 2 where L is a phenol-based ligand with two contiguous hexa-(N 4O 2) and tetra-coordination (O 2N 2) sites and M = Cu or Ni were prepared by a stepwise procedure. The prepared mono- and dinuclear complexes were characterized by elemental analysis, molar conductance measurements, X-ray crystallography, IR, NMR and UV-Vis spectroscopies. Characterization results confirmed the expected C 2 symmetrical geometry for the mononuclear zinc complex with trans-disposed pyridyl ligands. In contrast, the dinuclear complexes showed C 1 symmetrical structures so that, the Zn(II) ion resided in the six-coordination site with cis-disposed pyridyl ligands and the tetradentate compartment is occupied by M(II) ion in a square planar geometry. An unusual methyl elimination was occurred upon the introduction of the M(II) ions into the O 2N 2 coordination site of the mononuclear complex. The reason for these phenomena is an inherent structural feature of the dinucleating macroacyclic ligand that is discussed. © 2011 Elsevier B.V. All rights reserved.