Abstract
A set of explosives with nitro groups was selected for molecular mechanics calculations of charge density distribution particularly focused on the oxygen atom sof nitro groups. Calculations were done on the basic of accessible X-ray data without structure ganges except cases, where hydrogen atoms were not included.
Interatomic O…O distance sof nitro groups in neighboring molecules were markedly smaller then the van der Waals radii for these oxygen atoms. These atoms have a lower partial charge and therefore lower repulsion forces and higher dispersion forces.
The mutual repulsion and dispersion interactions were calculated for nitro groups in Compass force field. Moreover, the presence and power of hydrogen bonds , both connecting atoms in the individual molecules and connecting molecules in the crystals, results in a density increase of the substance.
Obviously, both these factors probably contribute to the unusually high density values of poly-nitro compounds.