Syntheses and molecular structures of three Cu(II) complexes with tetradentate imine-phenols

Abstract

Three Cu(II) complexes of N,N′-bis-(salicylidene)-1,3-diiminopropane ( 1), N,N′-bis-(salicylidene)-1,3-diimino-2,2-dimethylpropane ( 2), and N,N′-bis-(salicylidene)-1,5-diiminopentane ( 3) have been prepared and characterized by X-ray diffraction. All of the three complexes are four coordinated with Cu(II) in a tetrahedrally distorted square-planar geometry to two imine N atoms and two phenolate O atoms. Both 1 and 2 are monomeric with a 6-6-6 chelate ring structure and display the 2N2O donor atoms in a normal, tetradentate “ cis” configuration. However, in 3 two Cu(II) ions coordinate with bis-bidentate Schiff-base ligands, such that the Cu atoms are bridged by the two ligands; about each Cu atom, the arrangement of the iminophenolate groups is trans. The CuN1O1 and CuN2O2 planes intersect to form dihedral angles of 24.7° and 34.8° for 1 and 2, respectively, while the dihedral angle of two bidentate chelate planes of 3 is 40.5°.