No abstract

The photophysical properties of several W(CO),(a-diimine) complexes at 293 and 80 K are reported. For complexes of the type W(CO),L (L = substituted 1 ,IO-phenanthroline or 2,2'-bipyridine) three emissions are found while the lowest energy emission is not observed at room temperature for complexes of the type W(CO)4L (L = substituted 1,4-diaza-1,3-butadiene or pyridine-2-carbaldehyde imine). The highest energy emission in all these complexes is assigned to be L F in character: the other ones appear to have MLCT character. The occurrence of the lowest energy emission, which is related to the z-polarized b2 -b2* transition, depends on the MLCT character of this transition. This relationship is deduced from the resonance Raman excitation profiles and the luminescence excitation spectra of these complexes. Complexes with strong MLCT character for the z-polarized b2 -b2* transition show a low-energy emission, while this is not the case for complexes with much less MLCT character for this transition. These results are explained by the efficiency of the radiationless processes, which is large when metal-ligand stretching modes act as promoting modes. 1976, 98, 4105. (c) Kokkes, M. W.: Stufkens, D. J.; Oskam, A. J . Chem. SOC., Dalton Trans. 1984, 1005. (d) Caspar, J. V.; Westmoreland, T. D.; Allen, G. H.; Bradley, P. G.; Meyer, T.

No abstract

No abstract

No abstract