POSITION-DEPENDENT DEUTERIATION EFFECTS ON THE NONRADIATIVE DECAY OF THE (3)MLCT STATE OF TRIS(BIPYRIDINE)RUTHENIUM(II) - AN EXPERIMENTAL EVALUATION OF RADIATIONLESS TRANSITION THEORY

The nonradiative decay of the lowest electronically excited triplet states ((3)MLCT) of the title compound is studied and discussed on the basis of a previously developed theoretical framework. Extensive data on the luminescence lifetimes and resonance Raman intensities for a number of deuteriated analogues have been obtained in order to establish the role of the skeletal bipyridine vibrations in the nonradiative deactivation process. Careful inspection of the results documents position-dependent deuteriation effects on the nonradiative decay rate for Ru(bpy)(3)(2+). A model of the nonradiative decay process, incorporating the frequencies and intensities of a large number of totally symmetric acceptor vibrations, has been applied to the data for all the available isotopomers. A weak correlation between the observed and calculated relative nonradiative decay rates exists when only acceptor modes are assumed to vary with ligand deuteriation. However, inclusion of non-totally symmetric in-plane promoter vibrations yields calculated rates which are in an excellent agreement with the experimental data.