DEMONSTRATION OF THE DEGENERACY OF THE SINGLET AND TRIPLET-STATES IN 2,3-DIMETHYLENECYCLOHEXANE-1,4-DIYL BY MEASUREMENT OF ITS MAGNETIC-PROPERTIES

Magnetic susceptibility and magnetization of 2,3-dimethylenecyclohexan e-1,4-diyl (1), a conformationally restricted tetramethyleneethane (TM E), have been investigated at 2-20 K and applied fields of 0-5 T. Theo retical curves for a model in which singlet and triplet states are in equilibrium were fitted to the experimental data. In contrast with a p revious interpretation of the EPR signal intensities, singlet and trip let states were found to be almost degenerate (2\J/k(B)\ < 1 K), thus resolving a controversy as to the theoretical and experimental interpr etation of the ground state of 1.