 | |
| Names | |
|---|---|
| IUPAC name Silylidyne | |
| Systematic IUPAC name λ1-silane | |
| Other names Hydridosilicon, Silylidine | |
| Identifiers | |
3D model (JSmol) | |
| ChEBI | |
| ChemSpider | |
| 254 | |
| |
| |
| Properties | |
| HSi | |
| Molar mass | 29.093 g·mol−1 |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Silylidyne is a chemical substance occurring as a molecule found in stars and probably existing in interstellar space, or as amonolayer on the surface of solidsilicon. TheSiH molecule is aradical, and can be made experimentally by striking anelectric arc to silicon on a low pressurehydrogen gas.[1]
As a surface layer, silicon hydrides form when the silicon is cleaned with hydrofluoric acid. These hydrides decompose to SiH when heated to 750 K.[2] Other ways to coat a silicon surface in hydrogen is via reaction withatomic hydrogen, or hotsilane.[3] A (111) crystal face will become covered in the pure monohydride, but other faces on a silicon crystal will also have thedihydride andtrihydride groups.[3]
The silylidyne group, not to be confused with silylidyne, is a ≡SiH group that is bonded with a triple bond. The hydrogen can be substituted by other groups to make a more generic family of silylidynes. It is known as a ligand on molybdenum.
Silylidyne in space was first noticed insun spots in 1933. Later on it was found on the solar disk, photosphere, and in cool stars.Mira variable stars of typeM or S may have emission lines of SiH. In even coolerbrown dwarfs and planets, SiH is not found, but instead silicon takes form assilicon monoxide at low pressures, and SiH4 at high pressures. Minute amounts of SiH as a transient species may be found in these bodies as SiO and SiH4 react with water.[4]
The Si-H bond strength is 80 kcal/mol.[3]
The most prominent spectral band is due to A2Δ → X2Π transitions. Higher level excited states are the B2Σ− and C2Σ+, D2Δ, E2Σ+.[4]
The life time of the molecules in the A state is 530 nanoseconds. They decay to the X ground state.[4]
