Charge-localized ligands

A13CNMR investigation of the ligands 8-HO-quin, 4-Me-8-HO-quin and the complex [Znl ] (HL = 4-Me-8-HO-quin) in DMSO-d6 has demonstrated the complex to have a weakly ionic Zn—O interaction, with most of the negative charge localized on the oxygen.486... 

In contrast to this case, EL spectra presented in Fig. 130 demonstrate the importance of local environment for the energy of excited states. They have been obtained for a multi-component molecular structure comprising of a Nd3+ cation surrounded by four negatively charged pyrazolone ligands. The structure has a permanent dipole moment associated with the hemicyanine unit and this is expected to be enhanced by the rare-earth-containing anion [512]. The... 

Modeling shows that the pendant ligand in 61en places lithium in the proximity of Q and not C3. This would facilitate development of some degree of Ci— Li covalence. Further, any charge localized at Cj by development of the transition state would be stabilized by the silicon substituent. 

Figure 5. Schematic representation of bridge-mediated superexchange of the "electron" (top, left to right) and hole (bottom, right to left) type, illustrated for the case of intermolecular electron transfer between two metal/ligand (M/L) complexes, where D = M/ B = L/ L, and A = M,. The virtual intermediate states for the hole and eleetron processes involve, respectively, charge localization based on the filled ( valence") and empty ("conduction ) bands of the bridge.

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