Vibrational Couplings in Hydridocarbonyl Complexes: A 2D-IR Perspective.
Ricardo Fernández-Terán1, Jeannette Ruf1, Peter Hamm1
1Department of Chemistry, University of Zurich. Winterthurerstrasse 190, Zurich 8057, Switzerland.
Inorganic Chemistry
|May 16, 2020
Summary
Hydridocarbonyl complexes show strong vibrational coupling between M-H and M-CO modes when ligands are in a trans configuration. This coupling enhances M-H vibrations, aiding in determining oxidation and protonation states.
Area of Science:
- Organometallic Chemistry
- Spectroscopy
- Catalysis
Background:
- Hydridocarbonyl complexes are crucial industrial catalysts featuring metal-hydride (M-H) and metal-carbonyl (M-CO) bonds.
- Understanding the vibrational dynamics of these moieties is key to elucidating reaction mechanisms.
Purpose of the Study:
- To investigate the vibrational coupling between M-H and M-CO stretching modes in hydridocarbonyl complexes.
- To determine how ligand arrangement (trans vs. cis) influences vibrational coupling and M-H mode properties.
Main Methods:
- Utilized two-dimensional infrared (2D-IR) spectroscopy to probe vibrational coupling.
- Studied a series of iridium(I) and iridium(III) hydridocarbonyl complexes.
Main Results:
- Observed strong vibrational coupling and mode delocalization between M-H and M-CO modes in the trans configuration.
- Found no coupling in the cis configuration, with a significantly more anharmonic M-H mode.
- Demonstrated intensity borrowing from intense M-CO modes to the weaker M-H mode in the trans arrangement.
Conclusions:
- The trans configuration enhances M-H vibrations through coupling with M-CO modes, offering a strategy for spectroscopic detection.
- This vibrational coupling allows for direct infrared spectroscopic determination of oxidation and protonation states in mechanistic studies.
- Highlights potential for using vibrational coupling to study proton-coupled electron transfer reactions.
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