Tris(trimethylsilyl)silane

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][2]

Tris(trimethylsilyl)silane

Names
Preferred IUPAC name 1,1,1,3,3,3-Hexamethyl-2-(trimethylsilyl)trisilane
Other names TTMS, supersilane
Identifiers
CAS Number	1873-77-4
3D model (JSmol)	Interactive image
ChemSpider	109749
ECHA InfoCard	100.203.666
PubChem CID	6327365
UNII	NN5K4PS2OA
CompTox Dashboard (EPA)	DTXSID70940202
InChI InChI=1S/C9H27Si4/c1-11(2,3)10(12(4,5)6)13(7,8)9/h1-9H3 Key: SCHZCUMIENIQMY-UHFFFAOYSA-N
SMILES C[Si](C)(C)[Si]([Si](C)(C)C)[Si](C)(C)C
Properties
Chemical formula	C9H28Si4
Molar mass	248.663 g·mol−1
Appearance	colorless liquid
Density	0.806 g/cm3
Boiling point	82–84 °C (180–183 °F; 355–357 K) 12 Torr
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

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)