Intraligand transition

The complex shown in Figure 3.9 [104] is luminescent in the solid state at 77 K with three emission maxima at 431,448 and 460 nm. The excitation maxima are at 305 and 370 nm. The origin of the luminescence has been attributed to intraligand transitions with contributions of charge transfer character. 

Further examples of emissive cyclometallated gold(III) complexes are [Au(L)Cl] (L = tridentate carbanion of 4 -(4-methoxyphenyl)-6 -phenyl-2,2 -bipyridine) [53], as well as mono- and binuclear bis-cyclometallated gold(III) complexes, namely [Au (C N C )L ]" (C N C = tridentate dicarbanion of 2,6-diphenylpyridine L = depro-tonated 2-mercaptopyridine (2-pyS ), n = 0 L = PPh3 or 1-methylimidazole, n = 1) and [Au2(C N C )2(P P)](C104)2 (P P = dppm, dppe) respectively [54]. The crystal structures of the binuclear derivatives show intramolecular interplanar separations of 3.4 A between the [Au(C N C)] moieties, implying the presence of weak n-n interactions. The mononuclear complexes show absorption with vibronic structure at 380-405 nm (e > 10 cm ), attributed to metal-perturbed intraligand transition. 

Electronic absorption spectroscopy charge transfer transitions, 19 71 d-d transitions, 19 70, 71 flavocytochrome b, 36 269-271 intraligand transitions, 19 71-80 of organometallics, 19 69-80 Electronic coupling, between donor and acceptor wave functions, 41 278 Electronic nuclear double resonance spectroscopy, molybdenum center probes, 40 13... 

Compound dxzfdyz) —>d xy dxzfdyz) -A-d x2-y2 dzfdyz) Intraligand transitions... 

Studies that attempted to probe the electronic structure of the dithio complexes include the correlation of the electronic spectra in a series of R2 Dtc complexes of closed-shell configuration (584). In this study three major electronic absorptions in the spectra were found to be essentially unaffected by the central metal atom of the complexes and were considered intraligand transitions. 

Figure 4.75 Schematic representation of the charge transfer in various excited states of a metal complex. M is the metal centre and L stands for a ligand. LF is a ligand field transition, CTs are the charge transfer transitions, LL is an intraligand transition, and CTTS is a charge transfer to solvent...

The empirical rules for the d-d CD bands are supported not only by the measurement and interpretation of exciton CD in the UV region of the intraligand transitions as described in the next section, but also by the stereospecific formation of diastereomeric complexes having chiral ligands as described in Section 5.3.2. 

The fact that the intraligand transition is lowest in energy in ClRe(CO)3-(fnms-4-styrylpyridine)2 also allows a direct assessment of the effect of the coordination on the decay properties of the intraligand excited state. Data for both the photoisomerization by direct irradiation, Table 19, and the triplet sensitized isomerization, Table 20, of ClRe(CO)3(fra s-4-styrylpyridine)2 and frans-styrylpyridine... 

Figure 6.17(a) shows the time-resolved transient absorption spectra obtained for [Ru(dcbpy)2(bpzt)] in aqueous solution at pH 7. The important features are the bleaching of an absorption feature with a maximum at 450 nm and the growing in of a new band at 350 nm. The bleaching process can be attributed to the disappearance of the metal-to-ligand charge-transfer (MLCT) transitions in the excited state, while the feature at 350 nm is indicative of intraligand transitions of the dcbpy radical formed upon excitation of the complex. This type of behavior which is typical... 

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