A neutron-diffraction study of the crystal and molecular structure of triphenylene*

Abstract

Abstract The crystal structure of triphenylene, C18H12, at room temperature has been examined by neutron diffraction. Refinement of positional parameters and anisotropic temperature factors for all atoms gave a final R value of 0.048 over 810 independent reflections from a single crystal. Estimated standard deviations of carbon-atom positional parameters are about 0.007 Å (comparable with those from an earlier x-ray analysis) and those of hydrogen atoms are about 0.015 Å. Some of the differences between carbon-atom positions deduced from the two analyses may be significant. Molecular overcrowding is relieved by small deviations from exact planarity, possible departures of inter-bond angles from 120°, and changes in C–H bond lengths, so that intra-hydrogen-atom distances across the bay regions are about 1.9 Å.