Synthesis, characterization, and spectroscopic studies of tetradentate Schiff base chromium(III) complexes

Eight chromium(111) complexes of tetradentate Schiff bases have been prepared in situ by condensing of a substituted salicylaldehyde compound with ethylenediamine. These were characterized by elemental analysis, m.p., IR, molar conductivity, magnetic moment measurements, and electronic spectra. The free ligands were also characterized by H-1 and C-13 NMR spectra. The C-13 NMR spectra are discussed in terms of possible substituent effects. The IR and electronic spectra of the free ligand and the complexes are compared and discussed. The electrospray ionization (ESI) mass spectra of four free ligands and their complexes were measured. The deconvolution of the visible spectra of the complexes, C-2v symmetry, in DMSO yields three peaks at ca. 15600-17600, 18400-20400 and 20000-23100, and are assigned to the three d-d transitions, B-4(1g ->) E-4(g)(T-4(2g)); B-4(1g ->) B-4(2g) (T-4(2g)); B-4(1g ->) E-4(g)(T-4(1g)), respectively. The complexes showed magnetic moment in the range of 3.5-4.2 BM which corresponds to three unpaired electrons. (C) 2006 Elsevier Ltd. All rights reserved.