Jahn-Teller distortions and spectra

We have not yet discussed the spectra of d and complexes. By virtue of the simple -electron configurations for these cases, we might expect each to exhibit one absorption band corresponding to excitation of an electron from the t2g to the eg levels  

When a potential molecnlar geometry would result in degenerate orbitals that wonld be asymmetrically occnpied, Jahn-Teller distortions are likely. For example, the first two con-fignrations that follow shonld give distortions, but the third and fonrth should not  

FIGURE 11.9 Effect of Jahn-Teller Distortion on d Orbitals of an Octahedral Complex. 

Electron configurations have symmetry labels that match their degeneracies, as follows  

Designates a triply degenerate asymmetrically occupied state. 

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