Synthesis, spectroscopic characterization and EPR studies on electron transfer reactions of bis[N-(2,5-di-tert-butylphenyl)salicylaldiminato]copper complexes with PPh3

New bidentate N-(2,5-di-tert-butylphenyl)salicylaldimines bearing X = H, HO, CH3O, Br, NO2, 3,5-di-Br, 3-NO2-5-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)2, have been prepared and investigated by IR, UV-Visible, 1H NMR, ESR spectroscopy, magnetic measurements, as well as reactions of Cu(LX)2 with PPh3 were studied. It has been found that some complexes with X = HO and CH3O unlike their electron-withdrawing and unsubstituted analogues are readily reduced by PPh3 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 (63,65)Cu, 31P, 14N nuclei and aromatic protons.