Nanosecond-Lived Excimer Observation in a Crystal of a Rhodium(I) Complex via Time-Resolved X-ray Laue Diffraction.

Area of Science:

• Inorganic Chemistry
• Solid-State Chemistry
• Photochemistry

Background:

• Transient excimer formation in metal-metal bonded systems is rarely observed.
• Understanding excited-state dynamics is crucial for designing new materials and catalysts.

Purpose of the Study:

• To report the rare observation of transient rhodium-rhodium (Rh···Rh) excimer formation in a single crystal.
• To characterize the structural and electronic changes associated with this transient species.

Main Methods:

• Laser-pump/X-ray-probe time-resolved Laue diffraction method.
• Experiments conducted at 100 K with 100 ps time resolution.
• Theoretical modeling to complement experimental findings.

Main Results:

• Observed transient Rh···Rh excimer formation, with an excited-state lifetime of 2 ns at 100 K.
• Shortest-lived small-molecule species experimentally captured using this technique.
• Intermolecular Rh···Rh distance decreased from 3.379(4) to 3.19(1) Å upon 390 nm laser excitation.
• Metal-metal contact gained significant bonding character.

Conclusions:

• The observed structural changes are primarily attributed to the S₀ → S₁ electronic transition.
• This study provides unprecedented insight into the dynamics of excited-state metal-metal interactions.
• The findings pave the way for exploring short-lived excited states in various chemical systems.