FORMATION OF THIOKETENES BY THERMAL FRAGMENTATION OF 1,2-DITHIOL-3-ONES

Thioketenes 6 are formed in a Wolff-type rearrangement together with O CS by flash vacuum thermolysis (FVT) of 1,2-dithiol-3-ones 4 and ident ified by a combination of Ar matrix isolation FTIR sepctroscopy and co llisional activation mass spectrometry (CAMS), The thioketenes all hav e strong IR absorptions in the 1750 cm(-1) region ascribed to the C=C= S stretching vibration, The matrix LR and the CAMS of thioketenes 6a, 6d and 6e are identical with those of authentic samples generated by F VT of 1,2,3-thiadiazoles 7a, 7d and 2,3-dihydrobenzothiophene-2,3-dion e 9, respectively, A competing fragmentation of the dithiolones leads to the corresponding acetylenes. CO and S-2 were also identified.