A facile synthesis of mixed ligand Cu(II) complexes with salicylaldehyde and salicylaldimine ligands and their X-ray structural characterization
摘要:
High yield synthetic routes to the preparation of new mixed ligand Cu(II) complexes (1-7) derived from a sterically hindered salicylaldimine and the corresponding salicylaldehyde have been developed. The complexes could be obtained either forming a salicylaldimine preligand or two optional Cu(II) complex precursors. One-pot synthesis could also be used. The complexes have been fully characterized by means of elemental analysis, UV-Vis and IR spectroscopy. Crystal structures obtained for four [(3,5-di-tert-butylsalicylaldehydato)(N-R-3,5-di-tert-butylsalicylaldiminato)]Cu(II) (where R = phenyl (1), isopropyl (3), benzyl (5) and 2-phenylethyl (6)) complexes show that three of them are cis-isomers and one is a trans-isomer with respect to the phenolic O-atoms. Complexes 1, 5 and 6 form preferably loose dimers while 3 favors to exist in a loose polymeric structure in a crystal. In all these polynuclear forms the geometry around the Cu(II) ions is a distorted octahedron. (C) 2011 Elsevier B. V. All rights reserved.
Synthesis and X-ray structural characterization of sterically hindered bis(3,5-di-tert-butylsalicylaldiminato)Cu(II) complexes
摘要:
Bis(3,5-di-tert-butylsalicylaldiminato)Cu(II) complexes were prepared in high yields from a sterically hindered 3,5-di-tert-butylsalicylaldehyde and a variety of amines using three synthetic approaches. They were all thoroughly characterized by various spectroscopic methods (UV-Vis, IR, EPR and EI-MS). Crystal structures of seven complexes determined by X-ray crystallography show the Cu ion in a N2O2 coordination environment and a tetrahedrally distorted square-planar geometry. The UV-Vis and EPR results indicated that the complexes have the same geometry also in solution. In two solid state structures of the complexes the ligands have obtained an unusual cis-orientation whereas the rest of the complexes are trans-isomers. Computational studies carried out by the density functional theory method verified that in the case of complex with N-alkyl fragment the preferred isomer is trans, while the opposite behavior is observed for the complex with N-phenyl substituent. (C) 2012 Elsevier Ltd. All rights reserved.