Photoinduced Metallonitrene Formation by N₂ Elimination from Azide Diradical Ligands.

Area of Science:

• Catalysis
• Photochemistry
• Inorganic Chemistry

Background:

• Transition-metal nitrides and nitrenes are vital for catalytic nitrogen-atom transfer reactions.
• Their preparation often involves in situ generation via N2 elimination from azido precursors.
• Understanding the photo-induced processes is crucial for optimizing their catalytic potential.

Purpose of the Study:

• To elucidate the primary molecular mechanisms of platinum nitrene formation from a platinum azide precursor.
• To investigate the structural and electronic factors governing nitrogen (N2) loss.
• To understand the birth of the terminal metal-nitrogen core.

Main Methods:

• Femtosecond infrared spectroscopy was employed to study the primary photo-induced processes.
• Quantum-chemical calculations were used to support spectroscopic data analysis.
• Analysis focused on the formation of a platinum(II) nitrene with a triplet ground state.

Main Results:

• The formation of a unique platinum(II) nitrene with a triplet ground state was observed.
• Spectroscopic and computational data indicate initial occupation of a singlet excited state with an anionic azide diradical ligand.
• Subsequent intersystem crossing and near barrierless N2 loss lead to the triplet nitrene.

Conclusions:

• The study highlights the importance of the azide ππ* character in the productive, N2-releasing state.
• This provides a design principle for developing efficient nitrogen-atom transfer catalysts.
• The findings offer molecular-level insights into the photochemistry of platinum azides.