Penta-cyclo-[9.3.1.1(2,6).1(4,8).1(9,13)]octa-deca-1(2),8(9)-diene.

The title compound, C(18)H(24), was the main product of thermolysis of noradamantene dimer (hepta-cyclo-[9.3.1.1(2,6).1(4,8).1(9,13).0(1,9).0(2,8)]octa-deca-ne). The crystal structure was determined to prove that the thermolysis product of noradamantene dimer is favored by stretch release due to ring opening of the four-membered ring. The bond length of the quaternary C atoms of the starting material was calculated as 1.6 Å, enlarged in comparison to other single bonds. After the rearrangement, the stretch release of the above carbons leads to an increase of the distance between them (2.824 Å) with respect to the crystallographic data.