Ligand field states

Fig. 16. Schematic potential energy diagram of the low-lying ligand field states for d spin-state transition compounds. Full lines indicate the mechanism of forward and reverse LIESST effect. According to Ref. [135]...

The major contribution to the components of the D tensor as well as the deviations of the g values from 2.0023 arises from the mixing of ligand field states by SOC other contributions to D result from direct spin-spin coupling, which mixes states of the same spin S. The D tensor and the g matrix both carry chemical information as they are related to the strength and symmetry of the LF, which is competing and counteracting to the effects of SOC. Details on the chemical interpretation of the parameters by quantum chemical means is found in Chap. 5. 

Figure 6.3 Comparison between ligand field states of the [Tb(Pc)2] obtained ab initio for the real geometry, for the symmetrized geometry up to the D4d point group symmetry, and extracted from the...

Table 18.3 Energies of Octahedral Ligand Field States in Terms of A0. ...

Ligand field state of lowest energy given first, and energies are listed in the same order. ... 

The Ea for the dissolution of hematite by mercapto carboxylic acids in acid media in the presence of UV radiation was lower (64 5 kj mol ) than that for dissolution in the absence of radiation (94 8 kJ mol ) (Waite et al. 1986). The reaction in both cases was considered to involve formation of an intermediate organic-Fe surface complex which decomposed as a result of intramolecular electron transfer to release Fe". UV irradiation enhanced the decomposition of the surface complex either through excitation of the ligand field states associated with the free electrons on the S atoms, or through high energy charge transfer states. 

Fe(C0)3(a-diimine) (8), a photochemical reaction from 3d tt7v will lead to release of CO. This is in fact observed for several of these complexes in 2-Me-THF at 133K. It is unlikely that one of these reactions occurs from a ligand field state since the corresponding spin- allowed transitions are found below 400 nm and irradiation takes place at 514.5 nm. 

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