Bis(η⁵-cyclopentadienyl)(5,6-dihydro-1,4-dithiine-2,3-diselenolato-κ²Se,Se')titanium(IV) synthesis

bis(trichloromethyl)carbonate (triphosgene)

THF (refluxed over potassium, degassed)

Bis(η⁵-cyclopentadienyl)(5,6-dihydro-1,4-dithiine-2,3-diselenolato-κ²Se,Se')titanium(IV) (3.0 g, 6.66 mmol) and bis(trichloromethyl) carbonate (1.98 g, 6.66 mmol) were dissolved in dry THF (200 ml) under nitrogen. The mixture was heated to reflux for 1 h. Cooled mixture was quenched with methanol (10 ml) and stirred for further 15 min. The solids were removed by filtration and the filtrate was evaporated dry under reduced pressure. The residue was purified on silica using DCM:hexane (1:1) as eluent. Orange/yellow fraction collected. The solvents were removed under reduced pressure and the residue was re-dissolved in acetonitrile (100 ml) and heated to reflux with activated carbon for 0.5 h. The hot solution was filtered and the filtrate was concentrated to approximately half volume. The solution was left at -30°C overnight for crystallisation. Pale yellow solid was collected by filtration and washed with small amount of cold acetone. Yield 0.33 g (16%).

This is an intermediate in the synthesis of BEDT-TSF (BETS).

This procedure has been published in outline by Kato et al. and Courcet et al., to our knowledge however this is the first detailed synthetic procedure for this reaction. We would like to thank prof. Hiroki Akutsu for help with this procedure.

¹H NMR (400 MHz, 298K, CDCl₃) δ_H 3.44 (s, 4H, CH₂)

¹³C NMR (125 MHz, 298K, CDCl3) δ_C 185.49 (C=O), 116.92 (C=C), 33.12 (CH₂)