Abstract
The novel organometallic complexes Re(BQDI-R)(CO)(3)Cl with BQDI-R = 4,5-substituted o-benzoquinone diimines (R = H, Me, OMe, Cl) have been prepared and characterized by elemental analysis, IR, MS and H-1-NMR spectroscopic methods. Their electronic spectra display a long-wavelength absorption band which can be ascribed to a metal-to-ligand charge transfer (MLCT) transition from Re(I) to the ...
Abstract
The novel organometallic complexes Re(BQDI-R)(CO)(3)Cl with BQDI-R = 4,5-substituted o-benzoquinone diimines (R = H, Me, OMe, Cl) have been prepared and characterized by elemental analysis, IR, MS and H-1-NMR spectroscopic methods. Their electronic spectra display a long-wavelength absorption band which can be ascribed to a metal-to-ligand charge transfer (MLCT) transition from Re(I) to the low-lying pi*-orbitals of the o-benzoquinone diimine ligand, even though a significant degree of metal-ligand orbital mixing is occurring. The energy of this absorption band correlates very well with the nature of the substituents R in the 4,5-position of BQDI-R. In solvent series of decreasing polarity, the MLCT absorption maximum is shifted to longer wavelengths (negative solvatochromism). None of the Re(BQDI-R)(CO)(3)Cl complexes studied is photoluminescent at 298 or 77 K. (C) 2000 Elsevier Science S.A. All rights reserved.