Nitrenes are reactive intermediates in organic chemistry that contain a nitrogen atom with a valence of three, resulting in a neutral species with a lone pair of electrons. They are typically formed from the thermal or photochemical decomposition of azides or N-haloamines. Due to their high reactivity, nitrenes can participate in various chemical reactions, including cycloadditions and insertions into double bonds. These intermediates are important in synthetic chemistry because they can lead to the formation of diverse nitrogen-containing compounds. Their reactivity is influenced by factors such as the presence of substituents and the overall electronic environment, making them valuable tools for chemists in designing new molecules.