jp9b06968_si_001.pdf (260.69 kB)
Resonance Effects in the Raman Optical Activity Spectrum of [Rh(en)3]3+
journal contribution
posted on 2019-10-17, 18:34 authored by Thomas WeymuthRaman
optical activity spectra of Λ-tris(ethylenediamine)-rhodium(III)
{[Rh(en)3]3+} have been calculated at 16 on-,
near-, and off-resonant wavelengths between 290 and 800 nm. The resulting
spectra are analyzed in detail with a focus on the observed resonance
effects. Because several electronically excited states are involved,
the spectra are never monosignate, as is often observed in resonance
Raman optical activity spectra. Most normal modes are enhanced through
these resonance effects, but in several cases, de-enhancement effects
are found. The molecular origins of the Raman optical activity intensity
for selected normal modes are established by means of group coupling
matrices. In general, this methodology allows one to produce an intuitive
explanation for the intensity behavior of a given normal mode. However,
due to the complex electronic structure of [Rh(en)3]3+, there are some intriguing resonance effects the origins
of which could not be fully clarified in terms of group coupling effects.
Therefore, simple and general rules that predict how the intensity
of a specific normal mode is affected by resonance effects are difficult
to devise.