Comparative SCF study of the nature of the carbon–phosphorus bond in phospha-alkynes, RCP, and of the boron–sulphur bond in sulphidoborons, RBS

Abstract

Several molecular properties of phospha-alkynes, RCP, and sulphidoborons, RBS, (with R = H, CH₃, NH₂, OH, F and Cl in both cases) are computed using a ‘double-zeta plus polarization functions (DZP)’ basis set. This comparative study emphasizes that both the carbon–phosphorus bond in phospha-alkynes and the boron–sulphur bond in sulphidoborons have a triple nature. In the latter, the third bond is, however, π-dative and is formed by migration of a sulphur lone pair. In both types of bonds the charge distribution can be affected significantly by the substituents. Finally, it is shown that the BS group has greater electron-withdrawing character than the CP group.