A revision of van der Waals atomic radii for molecular crystals: N, O, F, S, Cl, Se, Br and I bonded to carbon

The Cambridge Structural Database has been used to determine the effective non-bonding (van der Waals) shapes of N, O, F, S, Cl, Se, Br and I atoms. In all cases these atoms were bonded to a single carbon atom. For O and N, the shapes are virtually spherical but for the remainder, the shape is more or less spheroidal, always having the shorter radius along the atom-to-carbon bond vector ('polar flatten- ing'). The results imply that these effective shapes are