anti-Tricyclo[4.2.1.12,5]deca-3,7-diene-9,10-dione

The title compound, C10H8O2, is a precursor to an unusual bis-homoaromatic dication and to heterodiamantanes and other oxa-cage compounds. Two independent molecules, each of which is situated on a center of symmetry, comprise the unit cell. Both molecules are in nearly identical chair conformations.

The title compound, C 10 H 8 O 2 , is a precursor to an unusual bishomoaromatic dication and to heterodiamantanes and other oxa-cage compounds. Two independent molecules, each of which is situated on a center of symmetry, comprise the unit cell. Both molecules are in nearly identical chair conformations.
Two independent molecules, each of which is situated on a center of symmetry, comprise the unit cell. Both molecules are in nearly identical "chair" conformations, with a maximum deviation between corresponding bond lengths of 0.01 Å.
The molecular packing exhibits several short intermolecular contacts, with the shortest being 0.15 Å less than the sum of the van der Waals radii.
Two related structures have been reported. The first (Eaton et al., 2002) has a chlorine atom in place of each hydrogen atom of the title compound, while the second (Masters et al., 1994) lacks the double bonds of the title compound and has methyl groups on each of the four bridgehead carbon atoms.

Experimental
The synthesis of the title compound, 4, is described in our previous structure report (Harris et al., 2008). Crystals for data collection were obtained from a chloroform solution.