A paradoxical case of a well-defined diradicaloid that has an unusually large singlet–triplet energy gap (ΔES-T) imparted by the thiophene sulfur atom is reported. Quantum chemistry, organic synthesis, molecular spectroscopies, X-ray crystal analysis and high-temperature magnetic measurements help account for the dichotomy between the large diradical character and large ΔEST.
- Justin J. Dressler
- Mitsuru Teraoka
- Michael M. Haley
