The cover shows three of the components that go into the formation of a noncovalent pnicogen bond, in this case the FH2P...NH3 complex. The upper diagram represents charge transfer from the N lone pair into the vacant σ* P-F antibonding orbital. The Coulombic attraction between the electrostatic potentials of the FH2P and NH3 subunits is illustrated in the middle figure. The lower figure depicts the shifts of electron density that occur when the two molecules combine to form the pnicogen-bonded complex, with charge shifting from green areas to purple. In the Review on page 1609, Steve Scheiner gives an overview of this type of noncovalent interaction, drawing parallelisms with the related chalcogen, halogen, and H-bonds.