Tetramethyleneethane-d8

Article abstract of DOI:10.1021/j100152a055

Tetramethyleneethane (TME) is a triplet non-Kekule 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 deg C about the central carbon-carbon 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 be consistent with a D_2d configured TME.In order to explore this point by removing proton hyperfine coupling, TME-d₈ was prepared.Again, no splitting was observed between the x- and y-lines for TME-d₈.This sets an upper limit for E of approximately 0.001 cm^-1.