STRUCTURE OF 1,3,5,7-TETRANITRO-3,7-DIAZABICYCLO[3.3.0]OCTANE - STRUCTURE SOLUTION FROM MOLECULAR PACKING ANALYSIS

The structure was solved with the molecular packing program MOLPAK, st arting with a molecular mechanics-geometry optimized model of an isola ted molecule. The best predicted crystal structures from the MOLPAK pr ocedure were subjected to lattice energy refinement with the WMIN prog ram. The MOLPAK/WMIN-predicted crystal structure, whose cell parameter s were closest to the experimental values. gave an initial R of 0.48 f or the 173 data to theta = 25 degrees. Four cycles of least-squares re finement of x, y, z and U gave an R of 0.27 for the 277 data to theta = 30 degrees. Final R = 0.038, wR = 0.044. There are no unusual interm olecular distances and crystal packing is normal.