Tetramethyleneethane (TME) is a triplet non-KekulC molecule that is currently the source of a difference between theory and experiment. The best theory places the energy of the triplet about 1 kcal/mol below the singlet at an angle of twist of 50 about the central carbon4arbon bond. However, the triplet ESR spectrum shows no splitting between the x-and y-lines, indicating that the zero field parameter, E, is 0 or very small. If it is the former, that would ...
