In-depth investigation of the iodine-nitrogen interaction mechanism using ab initio and density functional theory calculations

Abstract

In this paper, wesystematicallyinvestigate the interactions of I2with several representative nitrogen-containing building units (NBUs) using high-precisionabinitioand density functional theory calculations. Our findings reveal that the binding strengths of I2with NBUs arepositively correlated withthe hybridization degreesof N-2pelectrons. Further energy analysesindicate that the I-N orbital interaction determinesthe binding strength to a great extent. Especially for I2@NBU(sp3), itsσnbinding orbital formed by theσorbital of I2and the n orbital of NBU(sp3) exhibits nearly perfect orbital overlap. QTAIM analyses identifythe unique partially covalent feature of I-N bonds in I2@NBU(sp2/sp3) and the pure ionic feature in I2@NBU(sp). The I-N orbital interactions lead to remarkableelectron reorganizations in I2@NBUs. Moreover, we demonstrate thatthe binding strengths between NBUs and I2 can be effectively regulated through introducing electron-donating/electron-withdrawing functional groups. This study deepens the fundamental understanding of iodine coordination chemistry.