Synthesis, characterization and redox behavior of bis(N-1-adamantanyl- and N-2-adamantanyl-3,5-Bu-t(2)-salicylaldiminato)copper(II) complexes

Abstract

Two new bulky ligands, YNI (1-adamantyl)-3,5-Bu-t(2)-salicylaldimine (1), and N-(2-adamantyl)-3,5-Bu-t,-salicylaidimine (2), and their copper bis-chelate complexes, 3 and 4, have been prepared and their analytical, spectroscopic and magnetic properties, chemical and electrochemical redox reactivity are described. EPR and UV/Vis results [higher g(parallel to)/A(parallel to) , lower energy lambda (nm)] for 3 and 4 suggest a distorted square planar geometry with a higher degree of distortion for 3 than for 4. Chemical oxidation of 1-4 by ACN, on the basis of their EPR and UV/Vis spectra results in the formation of the free 1(center dot+), 2(center dot+) phenoxyl and Cu(II)-phenoxyl radicals complexes [g = 2.0065 (3(center dot+)), 2.0099 (4(center dot+)) and lambda(max) at ca. 430 and 720 nm]. Electrochemical studies have shown that the complexes possess ligand- and copper(II)-centered quasi-reversible and irreversible responses and the more distorted complex 3, having the bulkier 1-adamantyl on the imine nitrogen, was reduced at a more negative potential than the less distorted complex 4. (c) 2007 Elsevier Ltd. All rights reserved.