Tris(trimethylsilyl)silane explained

Tris(trimethylsilyl)silane is the organosilicon compound with the formula (Me₃Si)₃SiH (where Me = CH₃). It is a colorless liquid that is classified as a hydrosilane since it contains an Si-H bond. The compound is notable as having a weak Si-H bond, with a bond dissociation energy estimated at 84 kcal/mol. For comparison, the Si-H bond in trimethylsilane is 94 kcal/mol. With such a weak bond, the compound is used as a reagent to deliver hydrogen atoms. The compound has been described as an environmentally benign analogue of tributyltin hydride.^[1]

Reactions

The compound can be prepared by protonation of tris(trimethylsilyl)silyl lithium, which is derived from tetrakis(trimethylsilyl)silane:^[2]

(Me₃Si)₄Si + MeLi → (Me₃Si)₃SiLi + Me₄Si

(Me₃Si)₃SiLi + HCl → (Me₃Si)₃SiH + LiCl

Alternatively, the reaction of trimethylsilyl chloride and trichlorosilane in the presence of lithium delivers the silane directly but in modest yield:^[3]

3 Me₃SiCl + HSiCl₃ + 6 Li → (Me₃Si)₃SiH + 6 LiCl

Many coordination complexes have been prepared with (Me₃Si)₃Si⁻ (hypersilyl) ligand.^[4] Chalcogenide derivatives of (Me₃Si)₃SiLi are also well developed:^[5]

3 Me₃SiLi + E → (Me₃Si)₃SiELi (E = S, Se, Te)

References

1. Thirty Years of (TMS)₃SiH: A Milestone in Radical-Based Synthetic Chemistry. Chryssostomos Chatgilialoglu . Carla Ferreri . Yannick Landais . Vitaliy I. Timokhin . Chemical Reviews. 2018. 118. 14. 6516–6572. 10.1021/acs.chemrev.8b00109. 29938502. 49413857 .
2. Tris(trimethylsilyl)silane. Joachim Dickhaut, Bernd Giese. Org. Synth.. 1992. 70. 164. 10.15227/orgsyn.070.0164.
3. Spektroskopische Untersuchungen an Tris(trimethylsilyl)silan und -silan-d1. Bürger, H.; Kilian, W. . Journal of Organometallic Chemistry. 1969. 18. 2 . 299–306. 10.1016/S0022-328X(00)85398-X.
4. 10.1002/anie.200905950. Gold(I)-Mediated Silicon-Silicon Bond Metathesis at Room Temperature. 2010. Wilfling. Marion. Klinkhammer. Karl W.. Angewandte Chemie International Edition. 49. 18. 3219–3223. 20349479.
5. Book: 10.1002/9780470166444.ch4. The Chemistry of Metal Complexes with Selenolate and Tellurolate Ligands. Progress in Inorganic Chemistry. 2007. Arnold. John. 43 . 353–417. 978-0-470-16644-4.