Chalcogen–Nitrogen Radicals

The most important chalcogen–nitrogen radicals, stable radicals and their diamagnetic oligomers, and reactive short-lived species which are key intermediates in many important processes – production of smog, concentration of the ozone layer, emissions from combustion, transformations and rearrangements during redox, and nucleophilic reactions of sulfur- and selenium-nitrogen compounds – are surveyed. Their astronomical significance to planetary atmospheres, interstellar media, and comet tails is discussed. The formal similarity and functional relationships between the nitrogen chalcogenides from oxygen to tellurium are stressed throughout, while the origins of the profound differences between the oxides versus the sulfides, selenides, and tellurides are explored.