Synthesis of New Pentathiepin and Dithiatriselenepin Fused to Ferrocene via Dithiametallacycles

Abstract

Abstract 2,2-Dimethylferroceno[1,2-d][1,3,2]dithiastannole, a synthetic equivalent of unstable 1,2-ferrocenedithiol, was synthesized from N,N-dimethylsulfanoylferrocene by lithiation at the vicinal position, sulfurization, reduction, and protection with dichlorodimethylstannane. The dithiastannole, which has inherent low stability in organic solvents at ambient temperature, converted into diferroceno[1,2-c:1″,2″-g][1,2,5,6]tetrathiocin via 2,2-dimethyldiferroceno[1,2-d;1,2-h][1,3,6,7,2]tetrathiastannonin. The molecular structure of the tetrathiocin was determined by NMR, IR, mass spectra, elemental analysis, and X-ray crystallographic analysis. 2,2-Bis(η5-pentamethylcyclopentadienyl)ferroceno[1,2-d][1,3,2]dithiatitanole was synthesized from the tetrathiocin by the reduction and protection with bis(η5-pentamethylcyclopentadienyl)titanium dichloride in moderate yield. In contrast to the dithiastannole, the dithiatitanole was thermally stable up to 300 °C in the solid-state. Transformations into ferroceno[1,2-f][1,2,3,4,5]pentathiepin and -[1,5,2,3,4]dithiatriselenepin were successfully carried out, namely by the reactions of the dithiatitanole with some electrophiles containing sulfur or selenium atom(s). The molecular structure of the ferrocenopentathiepin was determined by NMR, IR, mass spectra, elemental analysis, and X-ray crystallographic analysis. The structure of the ferrocenodithiatriselenepin was determined by 1H and 13C NMR, IR, mass spectra, and elemental analysis, and supported by the 77Se NMR spectrum and theoretical calculations.