Abstract:

Acyclic hydroxo bridged binuclear copper(II) complexes of the formula [Cu2(L1-3)(NCS)2(OH)] (1a-1c) have been synthesized in situ from phenol based binucleating pentadentate macro-acyclic compartmental “end-off” type Schiff base ligands, viz., 2,6-bis{N-[3-(methylamino)propyl]iminomethyl}-4-methylphenol(L1), 2,6-bis{N-[3-(dimethylamino)propyl]iminomethyl}-4-methylphenol(L2), 2,6-bis{N-[3-(diethylamino)propyl]iminomethyl}-4-methylphenol(L3). The complexes are characterized by IR, UV-Vis, Single crystal X-Ray diffraction, emission and electrochemical studies. The UV-Visible spectrum of complex 1b shows a dramatic red shift of the d-d transition band when compared to that of 1a and 1c due to high distortion in the geometry of the complex. All the complexes exhibit quasi-reversible one electron redox processes (CuIICuII    CuII CuI  CuI CuI) at highly negative potentials (E1pc = -0.519 to -0.543 V, E2pc = -1.282 to -1.357 V). Density Functional Theory (DFT) calculations support the spectral study on the effect of distortion around the metal centres, electronic and electrochemical properties of the complexes.

Key words: Binuclear “End-off” Copper(II) Complexes, Alkyl substituents, Electrochemical Studies, DFT Studies.