The unsymmetrical chair–chair (CC) conformation of (E)-cyclononene is calculated to be 5.7 kJ/mol more stable than the axial-symmetrical twist-chair-chair (TCC) form; the calculated energy barrier for ring inversion of the CC conformation is 45.6 kJ/mol, while the barrier for swivelling of the double bond through the polyethylene bridge is 119.5 kJ/mol.
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