Synthesis and characterization of copper(II) metal(II) binuclear complexes of N,N′-bis(8-hydroxyquinoline-7-carboxaldene)-1,3-diaminopropane

Abstract

The magnetic, spectral and electrochemical properties of the homobinuclear copper(II) complex of N,N′-bis(8-hydroxyquinoline-7-carboxaldene)-1,3- diaminopropane (H 2L) and its binuclear complexes, CuCo, CuNi, CuCu, CuZn, CuCd and CuHg are reported. The electronic spectral data show that the dd transitional bands of the CuN 2O 2 chromophore in [CuLM](ClO 4) 2· nH 2O are blue shifted in the order, M = Ni 2+ > Co 2+ > Zn 2+ > Cd 2+ > Hg 2+, relative to the mononuclear [CuL]·3H 2O. This suggests that the CuN 2O 2 chromophore becomes more planar when [CuL]·3H 2O is coordinated to the second metal ion M. IR data suggests that H 2L acts as tetradentate in [CuL]·3H 2O and [CuLM(OAc) 2]· nH 2O but hexadentate in [CuLM](ClO 4) 2· nH 2O. Thermal analysis indicates that the water molecules are of crystallization in [CuLM](ClO 4) 2· nH 2O but of crystallization and hydrogen bonded in the other complexes. Magnetic data in the temperature 5–300 K range show a strong antiferromagnetic interaction in [CuLM](ClO 4) 2·H 2O, M = Co 2+ or Cu 2+ with − J = 112 and 229 cm −, respectively. The redox potentials of Cu(II)/Cu(I) in the heterobinuclear complexes are found to be around 1.055 V versus NHE which is almost the same as in the mononuclear complex. This behaviour has been discussed in terms of electronic and structural effects.