Chlorine bond distances in ClF and Cl<SUB>2</SUB> complexes

Intermolecular distances in weakly bound complexes have been usually interpreted in terms of van der Waals radii of atoms/molecules. Recently, it has been shown that for hydrogen-bonded complexes, one could empirically define a hydrogen bond radius [J. Chem. Phys. 114 (2001) 3880]. In this Communication, a similar approach is used for analyzing the B&#8230;Cl distances in B&#8230;ClF/Cl2 complexes, where B is the atom or center in the bonding partner. Chlorine bond radius for ClF and Cl2 are determined to be 1.28&#177;0.11 &#197; and 1.55&#177;0.07 &#197;, respectively. The ClF molecule with a non-zero dipole moment interacts more strongly and closely with B than Cl2 having zero dipole moment. However, the Cl bond radius in Cl2 complexes is still smaller than the van der Waals radius of Cl (1.80 &#197;), pointing to the importance of multipole moments in intermolecular interaction, in this case the quadrupole moment of Cl2