Synthesis, characterization, X-ray structure and magnetic study of the azido adducts of tridentate (NNO) Schiff base copper (II) complexes

Two new azido derivatives of tridentate Schiff base copper (II) complexes have been synthesized and characterized. X-ray single crystal structure analysis reveals that the complex [Cu(L1)(N3)] (1), containing 1-(N-salicylideneimino)-2-(N,N-diethyl)-aminoethane (HL1) as co-ligand, is monomeric in nature while complex [Cu(L2)(N3)]n (2), containing 1-(N-salicylideneimino)-2-(N,N-dimethyl)-aminoethane (HL2) as co-ligand, has a one-dimensional infinite chain structure in which copper (II) ions are bridged by single azido groups in end-to-end fashion. The co-ordination environment around copper (II) is square planar in the case of complex (1); of the four co-ordination sites, three are occupied by the two nitrogen atoms and the oxygen atom of the tridentate Schiff base ligand (HL1) and the fourth site is occupied by an azido group. On the other hand, in complex (2), the copper (II) co-ordination is distorted square pyramidal. The four in-plane co-ordination sites are similar to those in complex (1). The fifth apical coordination is provided by a nitrogen atom of the azido group of a symmetry related moiety with a long Cu–N bond distance, resulting in the polymerization of the complex. The variable temperature magnetic susceptibility measurements showed that the magnetic interaction in [Cu(L2)(N3)]n (2) is antiferromagnetic (J = −22.5(±0.2) cm−1) while as expected the complex [Cu(L1)(N3)] (1) is paramagnetic. The solution electronic spectra of the complexes show strong absorption bands associated with N3-→Cu(II) charge transfer transitions.

Simple variation of the substitution in the ligand affords different molecular architectures. While the ethyl substituted diamine gives a monomeric species, methyl substitution affords an infinite 1D chain involving copper (II) linked by μ-1,3-azido bridges. Consequently, the two complexes exhibit different magnetic properties.Figure optionsDownload as PowerPoint slide