Oxido-pincer complexes of copper(II) – An EXAFS and EPR study of mono- and binuclear [(pydotH2)CuCl2]n (n=1 or 2)
摘要:
The oxido-pincer ligand pydotH(2) (2,6-bis(1-hydroxy-1-o-tolyl-ethyl-eta O-2,O')pyridine) forms two different Cu-II containing complexes when prepared from anhydrous CuCl2. A combination of EPR spectroscopy and EXAFS allowed to structurally characterise the light-green dimer of the formula [(pydotH(2))CuCl(mu-Cl)(2)ClCu(pydotH(2))] and the penta-coordinate olive-green monomer [(pydotH(2))CuCl2]. The molecular entities imply that the ligand remains protonated upon coordination. When dissolved in DMF both compounds form monomeric species [(pydotH(2))CuCl2(DMF)] which could be characterised in detail by EPR. UV-Vis/NIR spectroscopy and electrochemical measurements. The assignments were supported by comparison with Cu-II complexes of the related ligands 2,6-bis(hydroxymethyl)pyridine (pydimH(2)) and 2,6-bis(1-hydroxy-1-methyl)pyridine (pydiPH(2)). (C) 2011 Elsevier Ltd. All rights reserved.