LOW-LYING ELECTRONIC STATES OF [RH(BPY)(3)](3- A COMPARATIVE-STUDY BASED ON HIGHLY RESOLVED AND TIME-RESOLVED SPECTRA(), [PT(BPY)(2)](2+), AND [RU(BPY)(3)](2+) )
H. Yersin et al., LOW-LYING ELECTRONIC STATES OF [RH(BPY)(3)](3- A COMPARATIVE-STUDY BASED ON HIGHLY RESOLVED AND TIME-RESOLVED SPECTRA(), [PT(BPY)(2)](2+), AND [RU(BPY)(3)](2+) ), Coordination chemistry reviews, 159, 1997, pp. 325-358
Optical emission and excitation spectra of [Rh(bpy-h(8))(3)](3+), [Rh(
bpy-h(8))(2)(bpy-d(8))](3+), [Rh(bpy-d(8))(3)](3+), [Pt(bpy-h(8))(2)](
2+), [Pt(bpy-d(8))(bpy-d(8))](2+), [Pt(bpy-d(8))(2)](2+), [Ru(bpy-h(8)
)(3)](2+), [Ru(bpy-h(8))(2)(bpy-d(8))](2+), and [Ru(bpy-d(8))(3)](2+)
are discussed. A series of trends-also including [Os(bpy)(3)](2+)-is u
ncovered. These trends, which are connected with an increase in metal-
d or MLCT character in the lowest triplet states, call for instance be
seen in transition energies, emission lifetimes, zero-field splitting
s, rates of spin-lattice relaxation, vibronic satellite structures, an
d changes of nuclear equilibrium positions on excitation. Moreover, th
e compounds investigated are also appropriate for consideration of the
concept of ''dual emission'', the relation between MLCT character and
covalency, as well as the current models of localization/delocalizati
on. Ln particular, a comparison of the properties of [Rh(bpy)(3)](3+)-
and [Ru(bpy)(3)](2+)-doped [Zn(bpy)(3)](ClO4)(2) provides illustrativ
e and very strong evidence for covalent delocalization in the lowest e
xcited states of [Ru/bpy)(3)](2+), while ligand-centered localization
is found in the states of [Rh(bpy)(3)](3+). Misinterpretations might o
ccur if the aggregation effects of the chromophores are not taken into
account. (C) 1997 Elsevier Science S.A.