Electroabsorption spectroscopy of charge-transfer states of transition-metal complexes. 2. Metal-to-ligand and ligand-to-metal charge-transfer excited states of pentaammineruthenium complexes
- Brookhaven National Lab., Upton, NY (United States)
The absorption spectra of Ru{sup II}(NH{sub 3}){sub 5}L and Ru{sup III}(NH{sub 3}){sub 5}L (L is an aromatic N-heterocycle or nitrile) complexes in 50:50 glycerol-water glasses at 77 K (D{sub s} = 3.9) are a function of the applied field in the 10{sup 6}-10{sup 7} V/m range. Analysis of the spectra in terms of the Liptay equations yields ground-excited state dipole-moment differences ranging from 4 to 37 D, depending upon the nature of L. The measured dipole moment differences, particularly those for the MLCT transitions, are much smaller than the values estimated from a simple consideration of the electron-transfer distances. The discrepancy between the observed and naive dipole moment estimates arises mainly from the multielectron nature of the response to excitation. Good agreement is obtained with the predictions of a model which includes refinement of the effective electron-transfer distance, the shift in the valence electron distribution in the excited state, and the effects of electron delocalization ({pi}-backbonding for Ru(II) and {pi}-bonding for the Ru(III) complexes). Other contributions, namely the dipole moment induced by the NH{sub 3} ligands and by the surrounding solvent molecules, are also considered. 55 refs., 11 figs., 4 tabs.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 263192
- Journal Information:
- Journal of Physical Chemistry, Vol. 100, Issue 20; Other Information: PBD: 16 May 1996
- Country of Publication:
- United States
- Language:
- English
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