Theoretical Studies On How To Tune The Pi-Hole Pnicogen Bonds By Substitution And Cooperative Effects

A systemic investigation of the substitution and cooperative effects on the P horizontal ellipsis N pi-hole pnicogen bond were performed via theoretical calculations. The structural and energetic properties of the binary complexes between a series of substituted benzonitrile and PO2F have been examined to study the substitution effect. The stability of the binary complexes increases in the order of CN < Br approximate to Cl < F < H < CH3 < NH2, in which all halogen atoms serve as the electron-withdrawing substituents. The cooperativity between halogen/triel bond with pnicogen bond were also studied in X horizontal ellipsis NC-Ph-CN horizontal ellipsis PO2F and Y horizontal ellipsis Br-Ph-CN horizontal ellipsis PO2F complexes with X = F-2, Cl-2, Br-2, FCl, FBr, BrCl, FCN, ClCN, BrCN, BH3, BF3, and Y = NH3, NH2CH3, NHCH2, HCN. It is found that the mutual effect of the interactions is weakened through the phenyl ring relative to the heterocyclic ring. The molecular electrostatic potential, atoms in molecules and natural bond orbital analysis were carried out to unveil the nature of these interactions. Several linear relationships have been established between the geometric parameters and the interaction energies or some electronic properties of the complexes. The distinct differences for the complexes involving BH3 and their BF3 analogs may be attributed to the greater pi electron density on the BF3 moiety, and the underlying reasons are discussed in detail.