Can lone pairs bind to a pi system? The water center dot center dot centerdot hexafluorobenzene interaction

[GRAPHICS] Ab initio calculations reveal a significant binding interaction between wat er and hexafluorobenzene in a geometry that points the oxygen lone pairs di rectly into the face of the pi system. The geometry is as anticipated from electrostatic arguments emphasizing the substantial quadrupole moment of th e aromatic. A second, off axis geometry is also found which is also consist ent with a substantial electrostatic interaction.