KCp* (Prepared in house)
THF (Distilled over potassium)
Trimethylsilyl chloride (Aldrich)

KCp* (1.0 g, 5.7 mmol) was suspended in THF (30 mL) and cooled to 0 °C. Trimethylsilyl chloride (0.74 mL, 7.6 mmol) was added drop wise and the resulting mixture was stirred overnight at room temperature. The resulting suspension was filtered through celite and the solvent was removed in vacuo to give the product as a yellow oil (Yield 0.79 g, 71 %).

Caution! KCp* is very sensitive to air/moisture, take care handle in glovebox.
Celite is baked in oven for 24 h prior to use and filtration done through a Schlenk frit. 

¹H NMR (400 MHz, C₆D₆): δ 1.81 (12H, s, Ar-Me); 1.18 (3H, s br, Ar-Me); -0.09 (9H, s, Si-Me)

Z. J. Tonzetich and R. Eisenberg, Inorg. Chim. Acta, 2003, 345, 340-344.
http://dx.doi.org/10.1016/S0020-1693(02)01276-8

Click to open interactive 1H NMR spectrum