The crystallography of the biscyclic dibenzacridines I. The electron distribution in 1.2:8.9-dibenzacridine

Abstract
The crystal and molecular structure of 1.2:8.9-dibenzacridine has been determined by a least-squares refinement of the complete two-dimensional X-ray data. The average estimated standard deviations of the carbon-carbon and carbon-hydrogen bond lengths are 0·009 and 0·08Å respectively, the mean C—H bond length in the molecule being 1·08Å. The observed ‘difference’ density and bond lengths are compared with predictions based on molecular-orbital theory. The molecular arrangement in the crystal is discussed in relation to the calculated charge distribution in the molecule.