Heterocumulene, 8 C4OS (4‐Thioxo‐1,2,3‐butatrien‐1‐on), C4S2 (1,2,3‐Butatrien‐1,4‐dithion) und C3S (3‐Thioxo‐1,2‐propadienyliden) ‐ Darstellung und spektroskopische Eigenschaften

Heterocumulenes, 8. — C4OS (4‐Thioxo‐1,2,3‐butatrien‐1‐one), C4S2 (1,2,3‐Butatriene‐1,4‐dithione), and C3S (3‐Thioxo‐1,2‐propadienylidene) ‐ Preparation and Spectroscopic Properties C4OS (8) is prepared by matrix photolysis and by flash pyrolysis of the precursor molecule 4, C4S2 (12) by matrix photolysis of 10, 11, and 13. Upon irradiation both 8 and 12 are split reversibly into C3S (9) and CO or CS. The IR and UV/Vis spectra of C4OS (8), C3S (9), and C4S2 (12) are reported. Quantumchemical calculations have been performed for the structures, harmonic vibrational frequencies, singlet‐triplet gaps, and electronic transition energies of 8 and 12.