Carbenes and Nitrenes: Recent Developments in Fundamental Chemistry

Area of Science:

• Chemistry
• Physical Chemistry
• Spectroscopy

Background:

• Carbenes and nitrenes exhibit singlet and triplet states, sometimes with comparable stability.
• These reactive intermediates can interconvert thermally or photochemically.
• Low-temperature reactions of carbenes and nitrenes often involve quantum tunneling.

Purpose of the Study:

• To provide an overview of recent advancements in the study of carbenes and nitrenes.
• To highlight the improved understanding of their singlet and triplet states.
• To discuss the interplay between experimental observations and computational insights.

Main Methods:

• Matrix photolysis and flash vacuum pyrolysis combined with matrix isolation at cryogenic temperatures for direct observation.
• Spectroscopic characterization of numerous singlet and triplet states.
• Computational methods to understand properties and reaction mechanisms.

Main Results:

• Significant progress in the direct observation of carbenes, nitrenes, and other reactive intermediates.
• Enhanced understanding of singlet and triplet states through spectroscopy and computation.
• Discovery of bistable carbenes/nitrenes and documented examples of tunneling, rearrangements, and fragmentations.

Conclusions:

• The study of carbenes and nitrenes has seen substantial progress, particularly in their direct observation and characterization.
• Interplay of spectroscopy and computations has deepened the understanding of their electronic states and reactivity.
• Emerging insights into chemical and physical properties, including tunneling and bistability, are refining chemical theories.