How does Jahn-Teller distortion affect the spectral absorbance peaks?

The Jahn-Teller effect occurs in certain geometries of transition metal complexes, particularly those with degenerate electronic states. When such a complex undergoes a Jahn-Teller distortion, it results in an irregular shape, often elongating or compressing certain bond lengths to lift the degeneracy of the electronic states.

This distortion causes the energy levels of the d-orbitals to split and shift, leading to changes in the way that electrons within the complex absorb light. Specifically, the absorption peaks in the spectral data corresponding to electronic transitions become asymmetric. This is due to the broadening and shifting of the absorption bands, which arises from the presence of different environments around the metal center as a result of the distortion. The transition states that would have led to symmetrical peaks now occur at various energy levels, leading to a distribution of transitions rather than a singular peak.

The other options are not consistent with the behavior observed in Jahn-Teller distorted systems. Peaks becoming symmetrical would imply a more uniform energy environment, which contrasts with the distortion's purpose of lifting degeneracy. Narrowing of the peaks would suggest less variability in the transition energies, while disappearance would imply that no transitions are possible, which also does not hold for Jahn-Teller distorted systems