Electronic spectra of 1,2-diiminetricarbonylrhenium(I)chloride complexes with imidazole derivatives as ligands

:A series: of Re(CO)(3)(1,2-diimine)Cl complexes; with bisimidazoles (BIIM) as 1,2-diimines have been synthesized and their electronic spectra studied . Compared with the absorption spectra of the free. BIIM ligands, the spect ra of the metal complexes display a shoulder at the low energy side of the intraligand (IL) bands. This additional absorption is assigned to the Re(I) to pi* (BIIM) metal-to-ligand charge transfer (MLCT) transition. Since imi dazoles. are weak pi-acceptor ligands, the MLCT band occurs at rather short wavelengths and is partially hidden by the intense IL bands of the BIIM mo iety. The complexes are photoluminescent both at room temperature and at 77 K. (C) 1999 Elsevier Science S.A. All rights reserved.