NO2+ is a molecular ion known as the nitronium ion. It consists of one nitrogen atom and two oxygen atoms, carrying a positive charge. This ion is often formed in chemical reactions involving nitric acid and is important in various chemical processes, including nitration reactions. The nitronium ion is a strong electrophile, meaning it can readily accept electrons from other molecules. This property makes it useful in organic chemistry for introducing nitro groups into aromatic compounds, which can significantly alter their chemical properties and reactivity.