Synthesis, Spectroscopic Characterization and EPR Studies on Electron Transfer Reactions of Bis[n-(2,5 Complexes With PPh3

Abstract

New bidentate N-(2,5-di-tert-butylphenyl)salicylaldimines bearing X = H, HO, CH<inf>3</inf>O, Br, NO<inf>2</inf>, 3,5-di-Br, 3-NO<inf>2</inf>-5-Br and 5,6-benzo substituents on the salicylaldehyde moiety, LxH, and their mononuclear bis[N-(2,5-di-tert-butylphenyl)salicylaldiminato]copper(II) complexes, Cu(Lx)<inf>2</inf>, have been prepared and investigated by IR, UV-Visible, 1H NMR, ESR spectroscopy, magnetic measurements, as well as reactions of Cu(Lx)<inf>2</inf> with PPh<inf>3</inf> were studied. It has been found that some complexes with X = HO and CH<inf>3</inf>O unlike their electron-withdrawing and unsubstituted analogues are readily reduced by PPh<inf>3</inf> via intramolecular electron transfer from ligand to copper(II) to give Cu-stabilized radical intermediates. The spectra of the primary radicals interpreted in terms of couplings of unpaired electron with 63,65Cu, 31P, 14N nuclei and aromatic protons. © 2002 Elsevier Science B.V. All rights reserved.