Ultrafast Intersystem Crossing and Structural Dynamics of [Pt(ppy)(μ-Bu₂pz)]₂.

Area of Science:

• Photochemistry
• Inorganic Chemistry
• Physical Chemistry

Background:

• Intersystem crossing (ISC) rates in transition-metal complexes depend on electronic and structural dynamics.
• Understanding these dynamics is crucial for controlling photochemical processes.

Purpose of the Study:

• To investigate the factors governing ISC rates in the prototypical d⁸-d⁸ dimetal complex [Pt(ppy)(μ-Bu₂pz)]₂.
• To elucidate the relationship between energy relaxation and structural dynamics in photoexcited states.

Main Methods:

• Broad-band transient absorption anisotropy.
• Ultrafast fluorescence up-conversion.
• Ab initio calculations.

Main Results:

• Upon excitation, ISC occurs in hundreds of femtoseconds from the S₁ to the T₂ state, followed by relaxation to T₁.
• Vibrational coherences along the Pt-Pt mode are observed and attributed to nuclear wavepacket dynamics.
• Structural flexibility influences dephasing prior to ISC.

Conclusions:

• The study demonstrates the interplay of electronic and structural dynamics in controlling ISC pathways.
• Provides new insights into the photoinduced dynamics of d⁸-d⁸ dimetal complexes.