Electron transfer bands

Keywords Cycloadditions, Chemical orbital theory. Donor-acceptor interaction. Electron delocalization band. Electron transfer band, Erontier orbital. Mechanistic spectrum, NAD(P)H reactions. Orbital amplitude. Orbital interaction. Orbital phase. Pseudoexcitation band. Quasi-intermediate, Reactivity, Selectivity, Singlet oxygen. Surface reactions... 

With the power of the donors and acceptors, changes occur in the important frontier orbital interactions (Scheme 2) and in the mechanism of chemical reactions. The continuous change forms a mechanistic spectrum composed of the delocalization band to pseudoexcitation band to the electron transfer band. 

Extrapolations from the Electron Transfer Bands of Permanganate. 99... 

The electron transfer bands are caused by an electron from a filled M.O. mainly situated on the reducing ligands being excited to an empty or partly occupied M.O. mainly localized on the oxidizing central atom... 

Table 1. Electron Transfer Bands (Wave-numbers in kK) of 3d-Group Tetroxo Ions...

Table 3. Frequency, v - -, (cm 1) of first Laporte allowed electron transfer band in metal oxides (predicted from optical electronegativity) comparison with experimental band gap, Eg.

Intensification of the 7F0 - 5D0j 7F0 - sDi and 7Fo bLi bands in the somewhat unstable Eu3+-diethyldithiocarbamate has been reported by J0RGENSEN 592. He has also observed genuine electron transfer bands from the highest filled molecular orbital to the partly filled 4/ shell in the bromo complexes of Nd3+, Sm3+, Eu3+, Tm3+ and Yb3+. In the case of Eu3+ the electron transfer bands occur [592] at 3200, 2660 and 2300 A corresponding to 31250, 37594 and 43478 cm-1 respectively. 

Sinha [380] whilst examining the terpyridyl complexes of the rare earths found only a very slight increase of the e value for the 5Ln band (c 3) compared to that in the aquo ion (e = 2.36). The bLi transition in the Eu(Terp)Cl3 complex occurs at 25390 cm-1 as a small sharp peak whilst that for the Eu(Terp)2Gl3 complex is split into two components occuring at 25410 and 25340 cm-1 respectively. The broad electron transfer bands are superposed on the 5In transition and occur at 24460 and 24350 cm-1 for Eu(Terp)Cl3 and Eu(Terp)2Cl3 complexes respectively. 

Three types of electronic transition can be distinguished among compounds of the d block transition elements d-d bands, charge transfer (or electron-transfer) bands and intra-ligand bands. Configuration interaction may make the distinctions rather hazy, however. 

However, spectroscopic investigations have revealed an even more direct way of measuring a quantity closely related to the electronegativities. Most electron-transfer bands are caused by transitions from filled MO s predominantly localized on the ligands X, say of MXS, to one of the two sub-shells mainly concentrated on M. It was observed that these absorption bands shift to lower wave numbers when the electronegativity of X decreases. This shift is so regular in all the MX6 studied that it is possible n>13 to define optical electronegativities, xopt, of... 

In the case of Nin, Ir111, Co , Cun, Rhin, and Pt17, the lower sub-shell is filled, and one only sees electron-transfer bands at a wave number A larger than suggested by Eq. (12). 

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