Synthesis, spectroscopic characterization, and oxidative C-C coupling in new copper(II) salicylaldiminates containing sterically hindered phenol

Abstract

New bis[N-(2,6-di-tert-butyl-1-hydroxyphenyl)salicylideneminato]copper(II) complexes bearing HO and CH3O substituents on the salicyaldehyde moiety were prepared, and have been characterized by elemental analyses., IR, UV/Vis, ESR spectroscopy, and magnetic moments. It has been found that in the synthesis of CH3O substituted complexes unlike HO bearing, the oxidative C-C coupling of coordinated salicylaldimine ligands take place. It has been suggested that the intermolecular H-bonding is a dominant factor in controlling of oxidative C-C coupling conversion. The powder ESR spectra of CH3O substituted compounds unlike of HO are typical of a triplet state Cull dimers with a half-field forbidden (DeltaM=+/-2) and the allowed (DeltaM=+/-1) transitions at 300 and 113 K.