3-Oxa-6,8-diaza-1,2:4,5-dibenzocycloocta-1,4-dien-7-one: a three-dimensional network assembled by hydrogen-bonding, pi-pi and edge-to-face interactions.

The title compound, C(13)H(10)N(2)O(2), is the first structure in which the urea moiety is incorporated into an eight-membered ring. Two molecules are found in the asymmetric unit, which are almost identical in their conformation and their hydrogen-bond pattern. The carbonyl O atom acts as a double acceptor for the NH groups of two adjacent molecules. In this way, infinite tapes are formed, which are connected via pi-pi and edge-to-face interactions in the second and third dimension. This hierarchical order of interactions is confirmed by molecular mechanics calculations. Force-field and semi-empirical calculations for a single molecule did not find the envelope conformation present in the crystal, indicating instead a C(s) conformation. Only with a model consisting of a hydrogen-bonded dimer or a larger hydrogen-bonded section was a conformation found that was similar to the one present in the crystal.