Sensitivity of pnicogen, chalcogen, halogen and H-bonds to angular distortions

Pnicogen, chalcogen, and halogen atoms have been shown previously to have some elements in common with H-bonds, including charge transfer into a σ∗ antibonding orbital. While H-bonds are known to have a strong propensity toward linearity, there is little known about the angular sensitivity of the former interactions. Ab initio calculations are performed that show that the noncovalent bonds formed between P, S, and Cl atoms with a N electron donor are strongly anisotropic, more sensitive to angular distortion than are H-bonds. Energy decomposition implicates exchange repulsion as the force that is chiefly responsible for this pattern.