title: Substituent effects on the properties of the hemi-bonded complexes (XH2P···NH2Y)(+) (X, Y=H, F, Cl, Br, NH2, CH3, OH).
abstract: Ab initio calculations have been performed to study the structures, binding energies, and bonding properties of the hemi-bonded binary complexes (XH2P···NH2Y)(+) with the substituents X and Y being H, F, Cl, Br, NH2, CH3, and OH. The P···N interactions in these open-shelled systems have typical pnicogen bond characteristics but much stronger than the usual pnicogen bonds in closed-shell systems. This P···N bond can be strengthened by an electron-withdrawing substituent X or an electron-donating substituent Y, the bonding energy varies from 17 kcal mol(-1) of (CH3H2P···NH2F)(+) to 54 kcal mol(-1) of (FH2P···NH2CH3)(+). A nearly linear X-P···N arrangement is required by the pnicogen bond P···N and results in a strong hyperconjugation and charge transfer from the N lone pair to the X-P σ* antibond orbital for α spin, the P···N interaction is described as a single-electron σ bond of β spin. The AIM and NBO analyses revealed that the P···N bonds in the majority of the hemi-bonded complexes are partly covalent in nature. Graphical Abstract The P···N interactions in the open-shelled systems (XH2P···NH2Y)(+) (X, Y=H, F, Cl, Br, NH2, CH3, OH) with bonding energy of 17~54 kcal mol(-1) have typical pnicogen bond characteristics but much stronger than the usual pnicogen bonds in closed-shell systems. This P···N bond can be strengthened by an electron-withdrawing substituent X or an electron-donating substituent Y.
authors.affiliation: School of Chemistry and Chemical Engineering, Southwest University, Tiansheng Road No.1, Chongqing, 400715, People's Republic of China. jilifei918@126.com.
authors.forename: Li Fei
authors.initials: LF
authors.lastname: Ji
authors.affiliation: School of Chemistry and Chemical Engineering, Southwest University, Tiansheng Road No.1, Chongqing, 400715, People's Republic of China. aylifnsy@swu.edu.cn.
authors.forename: An Yong
authors.initials: AY
authors.lastname: Li
authors.affiliation: School of Chemistry and Chemical Engineering, Southwest University, Tiansheng Road No.1, Chongqing, 400715, People's Republic of China.
authors.forename: Zhuo Zhe
authors.initials: ZZ
authors.lastname: Li
authors.affiliation: Citrus Research Institute, Southwest University, Tiansheng Road No.1, Chongqing, 400715, People's Republic of China.
authors.forename: Zhi Xing
authors.initials: ZX
authors.lastname: Ge
keywords: Hemi-bond; Pnicogen bond; Substituent effect; Weak interaction