Chalcogen–Nitrogen Bond: Insights into a Key Chemical Motif

Abstract

Chalcogen-nitrogen chemistry deals with systems in which sulfur, selenium or tellurium is linked to a nitrogen nucleus. This chemical motif is a key component of different functional structures, ranging from inorganic materials and polymers to rationally designed catalysts, to bioinspired molecules and enzymes. The formation of a selenium-nitrogen bond, and its disruption, are rather common events in organic Se-catalyzed processes. In nature, along the mechanistic path of glutathione peroxidase, evidence of the formation of a Se-N bond in highly oxidizing conditions has been reported and interpreted as a strategy to protect the selenoenzyme from overoxidation. Selenium is bonded to nitrogen also in the well-known ebselen, a selenenylamide with antioxidant, antimicrobic and cytoprotective activity and its formation/disruption has a crucial role for its pharmacological action. Focusing on examples taken from selenium organic chemistry and biochemistry, the selenium-nitrogen bond is described, and its strength and reactivity are quantified using accurate computational methods applied to model molecular systems. Significant trends show up when comparing to sulfur/tellurium-nitrogen bonds, reaffirming also in this context the peculiar and valuable role of selenium in chemistry and life