Structure and bonding in β-HMX-characterization of a trans-annular N---N interaction

Chemical bonding in the beta-phase of the 1, 3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) crystal based on the experimental electron density obtained from X-ray diffraction data at 20 K, and solid state theoretical calculations, has been analyzed in terms of the quantum theory of atoms in molecules. Features of the intra- and intermolecular bond critical points and the oxygen atom lone-pair locations are discussed. An unusual N center dot center dot center dot N bonding interaction across the 8-membered ring has been discovered and characterized. Hydrogen bonding, O center dot center dot center dot O and O center dot center dot center dot C intermolecular interactions are reported. Atomic charges and features of the electrostatic potential are discussed.