CHARACTERIZATION OF THE LOWEST EXCITED-STATES OF [RH(BPY-H(8))(N)(BPY-D(8))(3-N)](3-SPECTRA() BY HIGHLY RESOLVED EMISSION AND EXCITATION)

Highly resolved emission, excitation, and resonantly line-narrowed spe ctra, as well as emission decay properties of [Rh(bpy-h(8))(n)(bpy-d(8 ))(3-n)](3+) (n = 0, 2, 3; bpy = 2,2'-bipyridine) doped into [Zn(bpy-h (8))(3)](ClO4)(2) are presented for the first time. [Rh(bpy-h(8))(3)]( 3+) and [Rh(bpy-d(8))(3)](3+) exhibit one low-lying triplet T-1 at 12 757 +/- 1 and 22 818 +/- 1 cm(-1), respectively (blue shift 61 cm(-1)) , while [Rh(bpy-h(8))(2)(bpy-d(8))](3+) has two low-lying triplets at 22 757 +/- 1 and 22 818 +/- 1 cm(-1). The well-resolved vibrational sa tellite structures show, that the equilibrium positions of the triplet and the singlet ground S-0 state are not very different and that the force constants in T-1 are mostly slightly smaller than in S-0. Moreov er, the vibrational satellite structure is strongly dominated by vibra tional ligand modes, which demonstrates the pi pi character of the co rresponding transition. However, the occurrence of several very weak v ibrational modes of metal-ligand character displays a small influence of the metal ion. This is supported by the emission decay behavior. [R h(bpy-h(8))(2)(bpy-d(8))](3+) exhibits an emission which is clearly as signable to the protonated ligand(s), even when the deuterated ligand is selectively excited. Obviously, an efficient intramolecular energy transfer from the deuterated to the protonated ligand(s) occurs, presu mably mediated by the small Rh3+ d-admixture. A so-called ''dual emiss ion'' is not observed. Moreover, a series of spectroscopic properties of the lowest excited state of [Rh(bpy)(3)](3+) (energies of electroni c origins. emission decay times, zero-field splittings, structures of vibrational satellites, etc.) is compared to properties of bpy, [Pt(bp y)(2)](2+), [Ru(bpy)(3)](2+), and [Os(bpy)(3)](2+). This comparison di splays in a systematic way the increasing importance of the metal d an d/or MLCT character for the lowest excited states and thus provides gu idelines fur an experimentally based classification. In particular, th e lowest excited states of [Rh(bpy)(3)](2+) may be ascribed as being m ainly of (3) pi pi character confined to one ligand in contrast to th e situation found for [Ru(bpy)(3)](2+) where these states are covalent ly delocalized over the whole complex.